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Amide metathesis has been used to generate the first structurally characterized boryl complexes of calcium and strontium, {(Me3Si)2N}M{B(NDippCH)2}(thf)n (M=Ca, n=2; M=Sr, n=3), through the reactions of the corresponding bis(amides), M{N(SiMe3)2}2(thf)2, with (thf)2Li‐ {B(NDippCH)2}. Most notably, this approach can also be applied to the analogous potassium amide K{N(SiMe3)2}, leading to the formation of the solvent‐free borylpotassium dimer [K{B(NDippCH)2}]2, which is stable in the solid state at room temperature for extended periods (48 h). A dimeric structure has been determined crystallographically in which the K+ cations interact weakly with both the ipso‐carbons of the flanking Dipp groups and the boron centres of the diazaborolyl heterocycles, with K⋅⋅⋅B distances of >3.1 Å. These structural features, together with atoms in molecules (QTAIM) calculations imply that the boron‐containing fragment closely approaches a limiting description as a “free” boryl anion in the condensed phase., Amide metathesis is exploited as a route to boryl compounds of K, Ca, and Sr. The dimeric potassium system is shown by crystallographic and atoms‐in‐molecules studies to approach a limiting description as a “free” boryl anion.

Cyclopropenone 1,3-propanediol ketal is an increasingly versatile building block for the introduction of various C3 and dioxaspiro units due to the emergence of numerous methodologies for the application of strained hydrocarbons. This Practical Synthetic Procedure gives an updated synthesis for a basic ketal of cyclopropenone with lowered solvent toxicity and a detailed step-by-step guide for the safe production of potassium amide in liquid ammonia and for its application in the synthesis of the cyclopropene ring.

Adsorption of biochars (BC) produced from cash crop residuals is an economical and practical technology for removing nutrients from agricultural runoff. In this study, BC made of orange tree trunks and tea tree twigs from the Laoguanhe Basin were produced and modified by aluminum chloride (Al-modified) and ferric sulfate solutions (Fe-modified) under various pyrolysis temperatures (200°C–600°C) and residence times (2–5 h). All produced and modified BC were further analyzed for their abilities to adsorb ammonia and phosphorus with initial concentrations of 10–40 mg/L and 4–12 mg/L, respectively. Fe-modified Tea Tree BC 2h/400°C showed the highest phosphorus adsorption capacity of 0.56 mg/g. Al-modified Orange Tree BC 3h/500°C showed the best performance for ammonia removal with an adsorption capacity of 1.72 mg/g. FTIR characterization showed that P = O bonds were formed after the adsorption of phosphorus by modified BC, N-H bonds were formed after ammonia adsorption. XPS analysis revealed that the key process of ammonia adsorption was the ion exchange between K+ and NH4+. Phosphorus adsorption was related to oxidation and interaction between PO43 and Fe3+. According to XRD results, ammonia was found in the form of potassium amide, while phosphorus was found in the form of iron hydrogen phosphates. The sorption isotherms showed that the Freundlich equation fits better for phosphorus adsorption, while the Langmuir equation fits better for ammonia adsorption. The simulated runoff infiltration experiment showed that 97.3% of ammonia was removed by Al-modified Orange tree BC 3h/500°C, and 92.9% of phosphorus was removed by Fe-modified Tea tree BC 2h/400°C.

The benzylic functionalization of alkylpyridines is an important pathway for pyridine derivatives synthesis. The reaction partners, however, were mostly limited to highly reactive polar electrophiles. Herein, we report a potassium amide-catalyzed selective benzylic C-H bond addition of alkylpyridines to styrenes. Potassium bis(trimethylsilyl)amide (KHMDS), a readily available Brønsted base, showed excellent catalytic activity and chemoselectivity. A series of alkylpyridine derivatives, including benzylic quaternary carbon substituted pyridines, were obtained in good to high yield. Preliminary mechanistic studies revealed that the deprotonation equilibrium is probably responsible for the excellent selectivity.

The first catalytic α-alkylation reaction of benzyl sulfides and 1,3-dithianes with styrenes and conjugated dienes was developed under mild conditions by using a readily available Bronsted base potassium bis(trimethylsilyl)amide (KHMDS) as catalyst. The reaction displayed good functional group tolerance, high efficiency, and excellent chemoselectivity. A series of desired alkylation products were obtained in good to high yield. Preliminary mechanism studies suggested that two of the potassium amide catalyst molecules worked together in the catalytic cycle.

In this study, we first examined the hydrogen release, uptake, and reversibility properties of the KLi3(NH2)4-4LiH system and elucidated the influence of potassium cations' substitution into LiNH2 on the hydrogen storage properties of the LiNH2-LiH composite. Our results show that mixing of the potassium cations into LiNH2 can destabilize LiNH2, therefore decreasing the hydrogen desorption temperature and enhancing hydrogen desorption rate of the LiNH2-LiH system. Notably, the KLi3(NH2)4-4LiH composite exhibits a superior cycling stability compared with the LiNH2-LiH composite prepared under the same condition.

The role of intramolecular metal⋅⋅⋅π-arene interactions has been investigated in the solid-state structures of a series of main group compounds supported by the bulky amide ligands, [N(tBu Ar≠ )(SiR3 )]- (tBu Ar≠ =2,6-(CHPh2 )2 -4-tBuC6 H2 , R=Me, Ph). The lithium and potassium amide salts showed different patterns of solvation and demonstrated that the SiPh3 substituent is able to be involved in stabilizing the electrophilic metal. These group 1 metal compounds served as ligand transfer reagents to access a series of bismuth(III) halides. Chloride extraction from Bi(N{tBu Ar≠ }{SiPh3 })Cl2 using AlCl3 afforded the 1:1 salt [Bi(N{tBu Ar≠ }{SiPh3 })Cl][AlCl4 ]. This was accompanied by a significant rearrangement of the stabilizing π-arene contacts in the solid-state. Attempted preparation of the corresponding tetraphenylborate salt resulted in phenyl-transfer and generation of the neutral Bi(N{tBu Ar≠ }{SiPh3 })(Ph)Cl.

Lanthanide complexes supported by the tetradentate amine-bridged bis(phenolate) ligand LH2 [L = Me2NCH2CH2N{CH2-(2-O–C6H2– Bu 2 t -3,5)}2] were synthesized and structurally characterized. The reaction of (tBuCp)2NdCl(THF)2 with ligand LH2 in a 1:1 M ratio in THF at room temperature gave the amine-bridged bis(phenolate) lanthanide chloride LNdCl(DME) 1, (DME = 1,2-dimethoxyethane) in high yield. Complex 1 reacted with potassium amide to give the corresponding neodymium amido product LNdNPh2(DME) (2) in good yield. The ligand LH2 was subsequently treated with Cp3Ln to produce the amine-bridged bis(phenolato) cyclopentadienyl lanthanide complexes LLnCp(THF) (Ln = Yb (3) and Nd(4)). The definitive solid state molecular structure of complexes 1 and 3 were confirmed by single-crystal X-ray analysis. In complex 1 the central Nd atom is seven-coordinated with the coordination sphere completed by two oxygen atoms and two nitrogen atoms of the amine-bridged bis(phenolate) ligand, two oxygen atoms of DME molecule and one chlorine atom in a distorted capped octahedron while in complex 3 the Yb atom is six-coordinated by two oxygen atoms and two nitrogen atoms from the ligand, one oxygen atom from the coordinated THF molecule and a cyclopentadienyl group in a distorted octahedron.

Reactions of the extremely bulky potassium amide complexes, [KL'(η(6)-toluene)] or [KL"] (L'/L" = N(Ar*)(SiR3), Ar* = C6H2{C(H)Ph2}2Me-2,6,4; R = Me (L') or Ph (L")), with a series of first row transition metal(II) halides have yielded 10 rare examples of monodentate amido first row transition metal(II) halide complexes, all of which were crystallographically characterized. They encompass the dimeric, square-planar chromium complexes, [{CrL'(THF)(μ-Cl)}2] and [{CrL"(μ-Cl)}2], the latter of which displays intramolecular η(2)-Ph···Cr interactions; the dimeric tetrahedral complexes, [{ML'(THF)(μ-Br)}2] (M = Mn or Fe), [{ML"(THF)(μ-X)}2] (M = Mn, Fe or Co; X = Cl or Br) and [{CoL"(μ-Cl)}2] (which displays intramolecular η(2)-Ph···Co interactions); and the monomeric zinc amides, [L'ZnBr(THF)] (three-coordinate) and [L"ZnBr] (two-coordinate). Solution state magnetic moment determinations on all but one of the paramagnetic compounds show them to be high-spin systems. Throughout, comparisons are made with related bulky terphenyl transition metal(II) halide complexes, and the potential for the use of the prepared complexes as precursors to low-valent transition metal systems is discussed.

The interaction of 5,6,7,8-tetrafluoro- (1) and 5,7,8-trifluoro-6-(trifluoromethyl)quinoline (2) with sodium or potassium amide in liquid ammonia proceeds as a nucleophile (NH2−) addition on the 2-position of the pyridine ring, the respective adducts being oxidized to give the respective quinoline-2-amines. In the case of 1 the amide addition is concurrent with aminodefluorination on the 6- and 7-positions. 5,6,8- (3), 5,7,8-trifluoro- (4) and 5,7-difluoroquinolines (5) with one amide equivalent undergo deprotonation of the CH bond flanked by two ortho-fluorine atoms to produce the respective long-lived quinolinyl anions, which can be used as nucleophilic synthons as exemplified by their methylation to yield respective 6- and 7-methylpolyfluoroquinolines. With an excess of potassium amide the originally generated quinolinyl anions add an amide anion on the 2- or 4-position.

It is shown that in radioactive 4-amino-2-phenylpyrimidine, obtained as a minor product in the reaction of 4-chloro-2-phenylpyrimidine-4-14C with potassium amide in liquid ammonia, the 14C label is present in position 4 of the ring. This result proves that the formation of the 4-amino compound cannot be accomodated with a mechanism initiated by the attack of an amide ion on the 6 position, but probably occurs by an addition-elimination mechanism on the C(4) carbon atom.

The isomeric aminobromoquinolines in which amino groups and bromine atoms are attached to the pyridine nucleus were reacted with potassium amide in liquid ammonia at −33°. 2-Amino-3-bromo- and 2-amino-4-bromo-quinoline are converted via 3,4-didehydroquinoline into 2,3-diaminoquinoline together with some 2,4-diaminoquinoline. Ring transformations occur during reactions of 4-amino-2-bromo- and 3-amino-2-bromo-quinoline yielding 4-amino-2-methylquinazoline and 3-cyanoindole, respectively. 3-Amino-4-bromoquinoline yields a meta-rearranged substitution product i.e. 2,3-diaminoquinoline, while 4-amino-3-bromoquinoline does not react under the conditions applied. Mechanisms of the reactions described are discussed.

5-Amino-4-chloro-2-phenylpyrimidine and 4-chloro-5-methyl-2-phenylpyrimidine are converted into 4(5)-cyano-2-phenylimidazole and 4(5)-ethynyl-2-phenyl-imidazole, respectively, by reaction with potassium amide in liquid ammonia at - 33°.

Treatment of the carbinols (CH3)2C=C=C=C(OCH3)CR1R2(OH) (I) with potassium tert-butoxide in dimethyl sulfoxide gives derivatives of furan (III) if R2 = H and derivatives of 2,5-dihydrofuran (II) if R1 and R2 are both alkyl or if R1R2C = cyclohexyl. Acid-catalysed hydrolysis of II and III affords derivatives of 3-oxo-2,3-dihydrofuran (IV). Potassium amide in liquid ammonia, when used in excess, causes isomerisation of I into CH2=C(CH3)CH=C=C(OCH3)CR1R2(OH) (Ia).

On treatment of 4-amino-3-X-pyridazine (X=Cl, Br) with potassium amide in liquid ammonia 4-cyanopyrazole is formed. Under the same reaction conditions 4-amino-3,6-di-X-pyridazine (X=Cl, Br) undergoes a ring contraction into 3-(cyanomethyl)-1,2,4-triazole. The mechanism of both ring contractions is discussed.

When reacted with potassium amide in liquid ammonia both 3-bromo-and 4-bromo-1,5-naphthyridine are converted into a mixture containing 3-amino- and 4-amino-1,5-naphthyridine. The course of these reactions can be explained by a mechanism involving 1,5-naphthyridyne-3,4 as an intermediate. An abnormal reaction takes place during the aminations of 2-bromo-1,5-naphthyridine, a compound, C8H8N4, together with the chief product 2-amino-1,5-naphthyridine and 1,5-naphthyridine being formed. In the case of 3-bromo-2-ethoxy-1,5-naphthyridine an amination reaction afforded only 3-amino-2-ethoxy-1,5-naphthyridine. Syntheses of 3-bromo-2-ethoxy-1,5-naphthyridine and 3-amino-2-ethoxy-1,5-naphthyridine are described.

While treatment of 2-chloro-3-phenylpyrazine with potassium amide in liquid ammonia yields only 2-amino-3-phenylpyrazine, from 2-chloro-6-phenylpyrazine on the contrary two ring contraction products, 4(5)-phenylimidazole and 2-cyano-4(5)-phenylimidazole are obtained. From 2-chloro-5-phenylpyrazine a mixture of 2-amino-5-phenylpyrazine, 4(5)-phenylimidazole as well as 2-cyano-4(5)-phenylimidazole is formed. In the diphenyl series it has been established that, whereas 2-chloro-3,5-diphenylpyrazine gives only the corresponding 2-aminopyrazine, 2-chloro- 5,6-diphenylpyrazine gives a mixture of the amino product and two ring contraction products: 4,5-diphenylimidazole and 2-cyano-4,5-diphenylimidazole.2-Chloro-3,6-diphenylpyrazine was found to be relatively inactive towards potassium amide in liquid ammonia. This divergent behaviour is explained by the high susceptibility of the positions 3 and 6 of the 2-chloropyrazine for a nucleophilic attack as established by 14C- and 15N-labelling studies which were made previously.

The mechanism of the conversion of chloropyrazine into 2-cyanoimidazole by the action of potassium amide in liquid ammonia has been investigated. Using 2-chloro[4′ 15N]pyrazine and 2-chloro[2′ 14C]pyrazine it has been shown that ring contraction occurs by a nucleophilic attack of the amide ion at C(3), followed by fission of the C(3)-N(4) bond.

Amination of the 2-X-4,6-diphenylpyrimidines (X=F, Cl, Br) with potassium amide in liquid ammonia yields the corresponding 2-amino compounds, and in addition some dehalogenated product in the case of X = Br. It is proved, using the corresponding [1,3-15N]-labelled pyrimidines, that for the 2-chloro and 2-bromo compounds the amination goes to the extent of about 70% via a ring-opening [SN(ANRORC) mechanism] but that in the amination of the 2-fluoro compound no ring-opening takes place [SN(AE) process]. One of the supposed intermediates during the ring-opening i.e. 3-(cyanoimino)-1,3-diphenyl-1-propenamine could be isolated. Also the amination of 2-chloro-4-phenylquinazoline with potassium amide occurs to the extent of about 70% via the SN(ANRORC) mechanism. If instead of potassium amide in liquid ammonia an ethanolic ammonia solution is used at elevated temperatures, a considerable amount of the corresponding 2-amino compound is also formed via the ring-opening process, i.e. 34-67% (depending on the ammonia concentration). 2-Chloro- and 4-chloro-quinazoline behave similarly on reaction with ethanolic ammonia.

By treatment with potassium amide in liquid ammonia, 2-chloropyrazine is converted into a mixture of 2-cyanoimidazole, imidazole and 2-aminopyrazine. The mechanism of the formation of the two ring-contracted products is discussed.

1-Acetylthio-1-hexyne, , is cleaved by nucleophilic reagents. With primary and secondary amines, RR′NH (R = alkyl or aryl, R′ H or alkyl), N-substituted acetamides CH3CONRR′ and N-substituted thioamides C4H9CH2C(S)NRR′ are produced in good yields, the latter compounds presumably via the thioketene C4H9CHCS. In the case of ammonia, mainly acetamide and the polymer of the thioketene are obtained. Acethydrazide and 3,6-dipentyl-1,4 dihydro-1,2,4,5-tetrazine, I, have been isolated from the reaction mixture of acetylthiohexyne and hydrazine hydrate. Potassium amide, dissolved in liquid ammonia, converts acetylthiohexyne into hexynethiolate, C4H9CCSK (and acetamide); subsequent addition of ethyl bromide gives ethylthiohexyne, C4H9CCSC2H5, in excellent yield. If acetylthiohexyne is allowed to react with a mixture of ethanethiol and sodium ethanethiolate in dimethylformamide, the intermediate thioketene is trapped to produce the dithioester C4H9CH2C(S)SC2H5.

On treatment of 5-bromo-3-methyl-1-phenylpyrazole, 2-bromobenzo[b]thiophene and 2-bromobenzo[b]thiophene-1,1-dioxide with potassium amide in liquid ammonia bromine migration to the adjacent carbon atom was observed. Considerable evidence for the occurrence of an intermolecular transbromination was obtained.

Treatment of 3-nitro-1,6-naphthyridine, its 2-chloro-, 2-ethoxy- and 2-amino derivatives, with liquid ammonia, containing potassium permanganate, gave the corresponding 2-X-4-amino-3-nitro-1,6-naphthyridines (X = H, Cl, OEt, NH2). From 1H NMR spectroscopy sound evidence for the intermediacy of 2-X-4-amino-1,4-dihydro-3-nitro-1,6-naphthyridine is obtained. Similarly, from 5,8-dichloro(dibromo)-1,7-naphthyridine, the corresponding 2-amino-5,8-dichloro-(dibromo)-1,7-naphthyridines were formed on treatment with liquid ammonia/potassium amide/potassium permanganate. 1H NMR evidence for the intermediary C-2 σ-adduct has been obtained.

NMR spectroscopy reveals that the reaction between hepta-1,3,5-triene and potassium amide yields the all-trans heptatrienyl anion, which readily isomerizes to the cycloheptadienyl anion.

Treatment of 4-chloroquinazoline with lithium piperidide in piperidine at −75° yields a mixture of a stable open chain compound i.e. o-(piperidinomethylene)iminobenzonitrile and the corresponding 4-piperidino compound. When 4-chloroquinazoline is aminated with potassium amide in liquid ammonia at −75° only 4-aminoquinazoline is formed. By means of 15N-labelling it has been shown that about 50% of the 4-aminoquinazoline is formed via an ANRORC mechanism. The synthesis of 4-chloro-[3-15N]quinazoline is described.

In connection with an investigation being carried out in our laboratory on the influence of substituents on the course of reactions of halogenopyridines with potassium amide in liquid ammonia, the aminations of 2,3-, 2,4-, 2,5-, 3,4- and 3,5-dibromopyridine and of possible intermediate products, i.e., 4-amino-3-bromopyridine, the 5- and 6-bromo derivatives of 3-aminopyridine and the 3-, 4- and 5-bromo derivatives of 2-aminopyridine, have been studied. End-products are diaminopyridines or mixtures of these compounds and in some reactions a small amount of 4-amino-2-methylpyrimidine. The last-mentioned substance is the sole product isolated from the reaction mixture, obtained in the amination of 2,6-dibromopyridine3,4. The course of the aminations can be explained from what is known on the mechanisms of the aminations of the isomeric monobromopyridines and the mode of addition of ammonia to the triple bond in 3- and 4-substituted benzynes. For the formation of 4-amino-2-methylpyrimidine from 2,3-, 2,4- and 2,5-dibromopyridine a mechanism is suggested which is analogous to that assumed for the formation of that substance from 2,6-dibromopyridine3,4.

Aminations of 2,3-, 2,4- and 3,4-dibromoquinoline with potassium amide in different media have been investigated. Reactions of various types (bromine migration, dimerization, cine-substitutions and various ring transformations) were found to occur. Mechanisms for the conversions observed are proposed.

Evidence has been presented for the occurrence of 3,4-didehydro-1,8-naphthyridine in the reaction of 3-bromo(chloro)- and 4-bromo(chloro)-1,8-naphthyridine with potassium amide in liquid ammonia. The addition ratio of the amide ion (ammonia) to C(3) and C(4) in the didehydro bond was found to be 43/57, which is nearly identical with that found in 3,4-didehydroquinoline, 3,4-didehydro-1,7-naphthyridine and 3,4-didehydro-1,6-naphthyridine. It was calculated that 39% of the 4-amino compound, obtained from the 4-bromo-1,8-naphthyridine is formed by an SN(AE) process. In the reaction of 3-chloro-1,8-naphthyridine with potassium amide, besides the 3-amino and 4-amino compounds, 2-amino-3-ethynylpyridine and 3-ethynyl-2-(formylamino)pyridine were obtained, indicating a fission of the bond between C(2) and C(3). The last mentioned compound is also formed in the reaction of 4-chloro-1,8-naphthyridine. 1H-NMR spectroscopy has shown that 3-bromo(chloro)-1,8-naphthyridine forms with the amide ion a σ-adduct at C(2); this adduct formation preceded the formation of the didehydro compound. 2-Bromo(chloro)-1,8-naphthyridine gave exclusively 2-amino-1,8-naphthyridine. Conclusive evidence was obtained that part of the 2-amino compound was formed by a tele-substitution SN(AE)tele involving the 7-amino-2-chloro(bromo)-7,8-dihydro-1,8-naphthyridine (27% in the case of the 2-bromo compound, 8% in the case of the 2-chloro compound).

In the reaction of 4-chloro-6-R-pyrimidine-1-oxides (R=CH3 or C6H5) with potassium amide in liquid ammonia at −75°C or with liquid ammonia at −33°C besides the formation of the corresponding 4-aminopyrimidine-N-oxides, a ring contraction into 5-amino-3-R-isoxazoles (R=CH3 or C6H5) has been observed. A mechanism for the ring contraction reaction is postulated.

On treatment of 2-bromothiophene, 2,3-, 2,4-, and 2,5-dibromothiophene with potassium amide in liquid ammonia at − 75°, a bromine migration of position α to position β of the thiophene ring takes place. On treatment of the above mentioned compounds with potassium amide in liquid ammonia at − 33°, besides α to β bromine rearrangement, amination to 3-aminothiophene was observed. The mechanism of the transbromination is assumed to be an intermolecular process, involving dibromo- and tribromo-thiophenes. The formation of 3-aminothiophene does not occur via a didehydro intermediate, but it is the result of amination of a polybromothiophene, yielding an amino-bromothiophene, which is debrominated by reaction with amide ion or a thiophene anion.

During a study on the amination of 4-phenylpyrimidine in potassium amide/ liquid ammonia it was found that the extent to which the SN(ANRORC) mechanism operates in the amination largely depends upon whether an ammonium salt is used in quenching the reaction. The composition of the σ-adduct mixture, the structure of the open-chain intermediates, the inhibition of the SN(ANRORC) mechanism and the course of the amination in apolar solvents have been investigated. In addition, it has been found that, in the amination of 4-tert-butylpyrimidine, the SN(ANRORC) mechanism occurs to only a very limited extent.

By treating 4-chloro-2-phenylpyrimidine-4-14C with potassium amide in liquid ammonia, labelled 4-methyl-2-phenyl-s-triazine was obtained. By degradation of this s-triazine derivative by acid hydrolysis, the 14C-label was found to be present in one position only, viz. position 4. This result strongly indicates that in this ring-transformation no bicyclic intermediates are involved and that the opening of the pyrimidine ring occurs by fission of the C(5)C(6) bond and not of the C(4)C(5)bond. The mechanism of this reaction is discussed.

Evidence is presented that the conversion of 4-bromo-6-phenylpyrimidine into 4-amino-6-phenylpyrimidine by treatment with potassium amide in liquid ammonia at -75° occurs to the extent of about 80% according to a mechanism involving an open-chain intermediate.

Evidence is presented that the amination of 4-chloro-2,6-diphenylpyrimidine with potassium amide in liquid ammonia into the corresponding 4-amino compound occurs to the extent of about 45% by the ANRORC mechanism. In the amination of the 4-iodo- and 4-fluoro derivatives of 2,6-diphenylpyrimidine, however, the ANRORC mechanism is not operative at all. The amination of 5-bromo-4-chloro-2,6-diphenylpyrimidine into 4-amino-5-bromo-2,6-diphenylpyrimidine occurs to the extent of about 18% by the ANRORC mechanism. The synthesis of 5-bromo-4-chloro-2,6-diphenyl-[1(3)-15N]pyrimidine and of the 4-fluoro, 4-chloro and 4-iodo derivatives of 2,6-diphenyl-[1(3)-15N]pyrimidine is described.

The mechanism of the conversion of chloropyrazine into imidazole by potassium amide in liquid ammonia has been investigated. It has been proved, using the labelled compounds 2-chloro-[1-15N]pyrazine and 2-chloro-[2-14C]pyrazine, that this ring contraction occurs by a nucleophilic attack of the amide ion on position 3. The synthesis of 2-chloro-[2-14C]pyrazine starting from diethyl malonate labelled in the ethoxycarbonyl group, is described.

It has been found that 2-chloropyrazine, containing an excess of 15N in position 1, by treatment with potassium amide in liquid ammonia at −65° yields 2-aminopyrazine, in which the exocyclic nitrogen contains all the excess of 15N. An A(ddition)-N(ucleophilic)-R(ing)-O(pening)-R(ing)-C(losure) mechanism is proposed. The corresponding animation of 2-chloro[1(4)-15N]quinoxaline at −33° leads to 2-amino[1(4)-15N]quinoxaline. In the last-mentioned conversion an A(ddition)-E(limination) mechanism is operative.

In continuation of previous studies on the reactions of 2-bromo-6-ethoxy-, 2-bromo-6-methyl- and 2,6-dibromopyridine with potassium amide in liquid ammonia, aminations of twelve other 2-bromopyridines substituted at the 6-position, i.e. 6-amino-, 6-anilino-, 6-amidocarbonyl-, 6-(N-methylanilino)-, 6-phenyl-, 6-(2′-pyridyl)-, 6-phenoxy-, 6-(p-ethoxyphenoxy)-, 6-(m-ethoxy-phenoxy)-, 6-(p-fluorophenoxy)-, 6-chloro- and 6-nitro-2-bromopyridine were investigated. The following reaction types were observed: a. Substitutions producing 2-amino derivatives (from all starting substances except 6-amino-, 6-bromo-, 6-chloro- and 6-nitro-2-bromopyridine). b. Cine-substitutions producing 4-amino derivatives (from 6-methyl-, 6-ethoxy-, 6-phenoxy-, 6-(p-ethoxyphenoxy)-, 6-(m-ethoxyphenoxy)- and 6-(p-fluorophenoxy)-2-bromopyridine). c. Ring transformations yielding 6-substituted 2-methylpyrimidines by fission of the 3,4-carbon bond (from 6-phenyl-, 6-(2′-pyridyl)-, 6-phenoxy-, 6-(p-ethoxyphenoxy)-, 6-(m-ethoxyphenoxy)-, 6-(p-fluorophenoxy)- and 6-chloro-2-bromopyridine; from 2,6-dibromopyridine). d. Replacement of the 6-substituent producing the 6-amino compound (from 2-bromo-6-nitropyridine). e. Ring fission yielding 1, 3-dicyanopropene by cleavage of the N —C6 bond (from 6-amino-2-bromopyridine). The mechanisms of the reactions studied are discussed. In this connection the aminations of 2,6-dichloro-, 2,6-difluoro- and 2-amino-6-fluoropyridine were examined too.

Enyne-hydrocarbons, -alcohols and -ethers with the system can be converted into the isomers with a terminal acetylenic group , by treating them with an excess of potassium amide in liquid ammonia and hydrolysing the reaction mixture thus formed. In most cases yields are excellent. Enyne thioethers RCC-CHCH-SC2H5 (R alkyl) undergo an elimination of ethanethiol under these conditions. Hydrolysis affords the 1,3-diynes RCC-CCH in very good yields.

Propargyl ethers HCCCH2OR [R = alkyl or-CH(CH8)(OC2H5)] have been isomerized with good yields into the corresponding allenyl ethers CH2CCHOR by warming with potassium tert.-butoxide at 70°. These allenyl ethers can be metallated with butyllithium in ether or alkali amides in liquid ammonia. In ether, subsequent alkylation with alkyl halides R′Hal affords α-substituted allenyl ethers CH2CC(R′)OR. Alkylation in liquid ammonia produces a mixture of this same compound and the γ-substituted product R′CHCCHOR. In both cases reasonable yields are obtained. Sodamide and potassium amide quickly convert allenyl ethers CH2CCHOR into metallated propargyl ethers MCC-CH2OR (M = Na or K). If alkylation is not performed almost simultaneously with the metallation with sodamide or potassium amide, the only alkylation product obtained is R′CCCH2OR.

Reactions of 6-substituted derivatives of 2-halogenopyridines with potassium amide in liquid ammonia have been investigated. Together with aminations leading to the formation of 2-amino compounds, two unusual reactions were found to occur, i.e. reactions partially involving meta-rearrangement and conversions involving a ring transformation. The rearrangements took place in aminations of various substances (e.g. of 2-bromo-6-methylpyridine, 2-chloro-6-methylpyridine and 2-bromo-6-ethoxypyridine). Ring transformations occurred in aminations of 2,6-dibromo- and 2,6-dichloro-pyridine, 4-amino-2-methylpyrimidine being formed. The mechanism of the remarkable reaction last-mentioned is discussed.

Evidence is presented by means of 15N-labelling that the occurrence of an SN(ANRORC) mechanism in the amino-dehalogenation of 4-substituted 6-halogenopyrimidines by potassium amide in liquid ammonia is dependent on at least two factors. The C(2) position must be readily accessible to the attacking amide ion and the substituent at C(4) must not contain an acidic hydrogen atom adjacent to the pyrimidine nucleus. It is shown that the amount to which an SN(ANRORC) process occurs can be dependent on the reaction temperature.

Treatment of 2-halogenoquinoxalines and 3-substituted 2-halogenoquinoxalines with potassium amide in liquid ammonia yields the corresponding 2-aminoquinoxalines and benzimidazole. It was found - using 2-chloro-[2- 14C]quinoxaline - that the ring contraction does not involve a benzotriazepine derivative as intermediate and that the animation occurs via an AE-mechanism. In the case of 2-fluoroquinoxaline, there are indications that the amination goes partially via an addition-abnormal-elimination (EAa mechanism.

Treatment of 2-(diethylamino)-3-(methylthio)-5-phenyl-3H-azepine (3b, R = SMe) with potassium amide in liquid ammonia, followed by reaction of the anion formed with methyl iodide, gave 2-(diethylamino)-5-methyl-3-(methylthio)-5-phenyl-5H-azepine (5a), the structure of which was confirmed by X-ray analysis. Substitution at position 5 (as well as at C-3) was also observed on reacting the anion of 2-(diethylamino)-5-phenyl-3H-azepine, obtained by deprotonation of its conjugate acid with lithium diisopropylamide in N,N,N′,N′-tetramethyl-1,2-ethanediamine, with different alkyl halides.

The action of potassium amide in liquid ammonia on the N-oxides of 2-, 3- and 4-bromopyridine, 3-fluoropyridine, 2- and 3-bromo-4-methylpyridine, 3- and 4-bromo-5-ethoxypyridine and 3- and 4-bromo-2,5-dimethylpyridine has been investigated. 3-Fluoropyridine-N-oxide does not react under the conditions applied; the other N-oxides yield mixtures containing one or two amino compounds. The mechanisms of the formation of these substances are discussed. It was established that the SNAr2 (= AE) reaction is almost the sole reaction pattern in the aminations of the 4-bromopyridine-N-oxides and one of the mechanisms occurring in the aminations of the 2-bromopyridine-N-oxides. The 2-bromopyridine-N-oxides react partially and the 3-bromopyridine-N-oxides exclusively via 2,3-pyridyne-N-oxides as intermediates, except the N-oxides of 3-bromo-2,5-dimethylpyridine and 3-bromo-5-ethoxypyridine in the aminations of which 3,4-pyridyne-N-oxides play a role.

The action of potassium amide in liquid ammonia on several methyl substituted 3- and 4-bromo(chloro)pyridines, of 5-bromo-2-t-butylpyridine and of 3-bromo (chloro) and 4-bromo(chloro)-2,6-dimethylpyridine has been studied. The results of the reactions indicate the occurrence of derivatives of 3,4-didehydropyridine as intermediates. An interpretation is given of the influence of the substituent and the hetero atom on the course of the aminations.