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Diastereoselective radical coupling was achieved with chiral auxiliaries. The radicals were generated by anodic decarboxylation of five malonic acid derivatives. These were prepared from benzyl malonates and four menthol auxiliaries. Coelectrolyses with 3,3-dimethylbutanoic acid in methanol at platinum electrodes in an undivided cell afforded hetero-coupling products in 22–69% yield with a diastereoselectivity ranging from 5 to 65% de. Electrolyses without a coacid led to diastereomeric homo-coupling products in 21–50% yield with ratios of diastereomers being 1.17:2.00:0.81 to 7.03:2.00. The stereochemistry of the new stereogenic centers was confirmed by X-ray structure analysis and 13C NMR data.

In the title compound, C25H27NO4S, which crystallized as a racemate, the relative configuration of the adjacent OH and CH3 groups on the azepine ring is trans. The seven-membered azepin ring has a chair-like conformation. The planar aromatic rings of the benzyl and tosylate moiety are inclined to the planar 3-benzazepine ring by 78.39 (15) and 77.03 (14)°, respectively, and to each another by 13.82 (15)°. In the crystal, molecules are linked via O—H...O and C—H...O hydrogen bonds, forming double-stranded chains along the a-axis direction. The chains are linked via C—H...π interactions, forming a three-dimensional architecture.

The title compounds, C22H29NO2 (3) and C22H29NO2 (4) [systematic names: (1S*,2R*)-7-methoxy-2-methyl-3-(4-phenylbutyl)-2,3,4,5-tetrahydro-1H-3-benzazepin-1-ol and (1R*,2R*)-7-methoxy-2-methyl-3-(4-phenylbutyl)-2,3,4,5-tetrahydro-1H-3-benzazepin-1-ol, are diastereomers with the relative configuration of the adjacent hydroxyl and methyl groups at the seven-membered azepine ring being trans in (3) and cis in (4). In the crystals the orientation of these groups is −anti-periplanar (3) and +syn-clinal (4). In both cases, the crystals studied proved to be of a racemic mixture, with relative configurations (R*,S*)-3 and (R*,R*)-4. In both compounds, the seven-membered azepine ring has a chair-like conformation, and the 4-phenylbutyl side chain adopts a extended conformation in (R*,S*)-3, but a twisted conformation in (R*,R*)-4. In the crystal of (S*,R*)-3, molecules are linked via C—H...O hydrogen bonds, forming slabs parallel to the ac plane. In the crystal of (R*,R*)-4, molecules are linked via O—H...N hydrogen bonds, forming chains propagating along the c-axis direction. The chains are linked by C—H...O hydrogen bonds, forming slabs parallel to the ac plane.

Tris(pentafluorophenyl)borane reacts with 9,9-dipropargylfluorene (5) in a 2:1 ratio under ambient conditions to yield a statistical mixture of the double-1,1-carboboration products (Z,Z)-, (E,Z)-, and (E,E)-6. Photolysis of the product mixture yields a new mixture that is substantially enriched in the (Z,Z)-6isomer. Treatment of 5with the P(o-tolyl)3/B(C6F5)3frustrated Lewis pair gave the zwitterionic eight-membered heterocycle 7a, which is the product of a 1,1-carboboration of one alkynyl unit followed by an intramolecular 1,2-addition of the in situ generated new FLP to the remaining alkynyl moiety. The reaction of the PtBu3/B(C6F5)3FLP gave an analogous result, yielding 7b. Treatment of 1,2-diethynylbenzene (9) with the PtBu3/B(C6F5)3FLP resulted in deprotonation, forming the phosphonium/alkynylborate salt 10. The reaction of triarylphosphine/B(C6F5)3pairs using the phosphines P(o-tolyl)3and P{Ph2[2,5-bis(trifluoromethyl)phenyl]} resulted in clean 1,2-P/B FLP additions to a CC triple bond to yield the products 11and 12, respectively. Eventually, the reaction of 9with the poorly nucleophilic phosphine P(C6F5)3in combination with B(C6F5)3gave the zwitterionic product 14, which is thought to result from a two-step reaction involving 1,1-carboboration followed by an exo-dig cyclization by means of a 1,2-P/B FLP reaction of the in situ generated alkenylborane Lewis acid and P(C6F5)3to the remaining alkynyl unit. The products (Z,Z)-6, 7a,b, 10, 12, and 14were characterized by X-ray crystal structure analyses. [ABSTRACT FROM AUTHOR]

Hydroboration of dimesitylvinylphosphine with Piers’ borane [HB(C6F5)2] gives the ethylene-bridged intramolecular frustrated P/B Lewis pair 1. It adds pyridine, tert-butyl isocyanide or pivalonitrile to the strongly electrophilic boron center to yield the respective adducts 5–7. Compound 1undergoes a 1,1-phosphine/borane addition to the terminal nitrogen center of phenyl azide to yield the five-membered heterocycle 8, featuring a pendant –NN–Ph. This can be regarded as a boron-stabilized intermediate of a Staudinger reaction. Benzaldehyde and phenyl isocyanate undergo 1,2-P/B additions of 1to their reactive carbonyl groups to yield the corresponding six-membered heterocycles 9and 10, respectively. The P/B Lewis pair reacts with nitrosobenzene by 1,2-addition to the –NO unit under P–N and O–B bond formation to give the six-membered heterocycle 11. The compounds 5–11were characterized by X-ray crystal structure analyses. [ABSTRACT FROM AUTHOR]

Condensation of allylcyclopentadiene 1with acetone in the presence of pyrrolidine gave 2-allyl-6,6-dimethylfulvene (2). Methyllithium addition gave lithium 1-allyl-3-tert-butylcyclopentadienide (3). Transmetallation with 0.5 equiv. of ZrCl4yielded the respective functionalized zirconocene dichloride complexes meso-4and rac-4, which were both isolated isomerically pure. With 10 mol% of [Cl2(PCy3)2RuCHPh] the rac-4diastereoisomer underwent a clean intramolecular ring-closing olefin metathesis reaction to yield the ansa-zirconocene complex rac-6. The complexes meso-4, rac-4and rac-6were characterized by X-ray diffraction. Treatment of the open metallocenes meso-4and rac-4, respectively, with excess methylalumoxane gave rather active ethene polymerization catalysts. The corresponding catalyst derived from the conformationally restricted bulky ansa-metallocene rac-6is markedly less active. [ABSTRACT FROM AUTHOR]

Bis-acylhydrazones of 2,6-pyridinedicarbaldehyde are introduced as planar pentadentate ligands for the coordination of lanthanide(iii) ions. With large cations (e.g.lanthanum(iii)) 1 : 1 as well as 2 : 1 ligand-to-metal complexes are formed depending on the stoichiometry of the reaction. The different complexes are distinguished by NMR spectroscopy and ESI MS in solution and they can be characterized by X-ray diffraction. With the small lutetium(iii) ion only the 1 : 1 complex is formed. In the 1 : 1 compounds, anions such as nitrate fill up the coordination site at the metal ion. However, in some cases anion substitution by solvent molecules is observed in the solid state leading to cationic and even dicationic coordination compounds. [ABSTRACT FROM AUTHOR]

The investigation of the electronic and steric properties of 4,5-disubstituted imidazolylidenes is reported, as well as their successful application as organocatalysts in the formation of γ-butyrolactones by conjugate Umpolung. [ABSTRACT FROM AUTHOR]

A series of benzobisimidazolium salts 1a–dhas been prepared by tetraalkylation of benzobisimidazol. The salts 1a–dreact with two equivalents of [Pt(Cl)2dppe] in the presence of 2.2 equivalents of sodium acetate to yield the dinuclear biscarbene complexes 2a–d. Under the same reaction conditions, the benzobisimidazolium salts react with only one equivalent of [Pt(Cl)2dppe] and one equivalent of sodium acetate to yield the monometalated carbene/benzimidazolium derivatives 3a,3c. Benzobisimidazolium salt 1creacts with two equivalents of nickelocene to give the biscarbene bridged dinuclear nickel complex 4. Treatment of 4with two equivalents of 4,4′-bipyridine leads to the formation of the CpNiII-cornered molecular rectangle 5. [ABSTRACT FROM AUTHOR]

Hydroboration of allyl(dimesityl)phosphane with HB(C6F5)2gives the intramolecular five-membered P–B Lewis pair 7, that was characterized by X-ray diffraction. Similarly, HB(C6F5)2addition to the substrates (mesityl)2P–CRCH2(R = CH3, Ph) yield the corresponding (mesityl)2P(μ-CHRCH2)B(C6F5)2products 9a(R = CH3) and 9b(R = Ph) that show a weak intramolecular PB interaction. The activation energy of the (reversible) PB cleavage of these substrates was determined by dynamic 19F NMR spectroscopy (9a: ΔG≠inv(280 K) = 11.7 ± 0.4 kcal mol−1). Compounds 9band 9cshow similar values. Compound 9cwas prepared by HB(C6F5)2addition to (mesityl)2P–CHCHSiMe3. Compound 9areacts rapidly with dihydrogen (2.5 bar) at room temperature in pentane to give the zwitterionic H2-activation product (mesityl)2PH+(μ-CHMeCH2)BH−(C6F5)2(11). [ABSTRACT FROM AUTHOR]

An unprecented dimeric capsular assembly of a tetramethylated C-hexyl resorcinarene and an expected one from unsubstituted C-butyl resorcinarene with tetramethylammonium cation are described. Surprisingly tetramethylated C-hexyl resorcinarene, with no apparent possibility for intra-capsular hydrogen bonds, forms a capsule which is held together solely by the cationπ interactions and the complementary geometry of the spherical guest cation and the concave resorcinarene host. The C-butyl resorcinarene capsule, as in the case of dimeric resorcinarene capsules reported earlier, is mediated viasolvent molecules and intra-capsular hydrogen bonds. We also report here two co-crystals of C-methyl resorcinarene and one of C-(3-hydroxy)propyl resorcinarene with R2,R′2-type of alkyl ammonium halide salts. These structures manifest the difficulty of structure control and prediction due to competing and multiple interactions in the crystalline state. The design of the resorcinarene-based host–guest system so as to enable prediction or inducement of a specific crystal packing or structural arrangement of host and guest, is very difficult, if not impossible due to the cameleon nature of resorcinarenes in their ability to form weak interactions. [ABSTRACT FROM AUTHOR]

Starting with (S)-aspartate, methyl (S)-2-[1-allyl-4-(4-methoxybenzyl)-3,6-dioxopiperazin-2-yl]acetate 10 was synthesized in a four-step synthesis. Deprotonation of 10 and subsequent trapping of the first cyclization product led to the bicyclic mixed acetal 13 in 15% yield. The low yield of 13, compared with the yield of the corresponding glutamate derivatives, is explained by the higher energy (strain) of the bicyclo[2.2.2]octane system and the lower conformational flexibility of the shorter acetate side chain. The formation of a six-membered Na+-chelate 12 as intermediate is responsible for the high diastereoselectivity of the cyclization step. [ABSTRACT FROM AUTHOR]

Cyclic diamino plumbylenes derived from saturated heterocycles are obtained from deprotonation of diamines and subsequent reaction with PbCl2, or by reaction of a suitable diamine with Pb[N(SiMe3)2]2. Single crystal X-ray studies have been used to probe the solid state structures of a range of these complexes and have shown the fine balance between monomer and dimer formation which is related to the bulk of the organic group attached to the nitrogen atoms. Dimerisation is also shown to effect structural changes within the core of the heterocyclic plumbylene. [ABSTRACT FROM AUTHOR]

Staudinger reaction of dppm-CN (5) gave the corresponding bis(N-phenylphosphinimino)acetonitrile system (6). Deprotonation with LDA furnished the corresponding anionic ligand 9. Its reaction with [(CO)2RhCl]2 gave the corresponding κ2N,N′-chelate complex 11. X-Ray diffraction revealed a non-planar boat-like conformation of the six-membered chelate ring in the crystal. Treatment of 9 with [(nbd)RhCl]2 gave the six-membered chelate complex 12 which features a different twist-like structure in the solid state, as does 13, which was formed by reacting 9 with [(cod)IrCl]2. [ABSTRACT FROM AUTHOR]

Treatment of the α-dimethylamino[3]ferrocenophane derivative 3with n-butyllithium results in a directed o-metalation at the adjacent Cp ring of the ferrocene unit to selectively yield the ( R*, R*, p- S*) diastereomer 4. Similarly, lithiation of rac- 12gives ( R*, p- S*)- 13. Both these compounds form meso-type dimers in the crystal that feature a central C 2Li 2four-membered-ring moiety. Compound 13crystallizes with excess n-butyllithium to form a ( 13· n-BuLi) dimer that was also characterized by X-ray diffraction. Directed lithiation of the nonbridged ferrocene derivative 1-(dimethylaminobenzyl)ferrocene ( 16) with tert-butyllithium resulted in an opposite stereoselectivity to yield ( R*, p- R*)- 17, which forms a chiral dimeric structure in the solid state, as was revealed by its X-ray crystal structure analysis. [ABSTRACT FROM AUTHOR]