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The anthracene based fluorescent PET chemosensor 1 and the azo-dye based chemosensor 2 show high selectivity for Na+ over other alkali and alkaline-earth metal cations in the 12–300 mM concentration range in 50 ∶ 50 MeOH–H2O at pH 7.4. Chemosensor 1 shows fluorescence ‘off-on’ switching upon Na+ complexation with λFmax of 440 nm and a log βNa of 2.5 (±0.05) and a pKa of 5.3 with no concomitant changes in the absorption spectra. Conversely, 2 displays only a weak fluorescent emission at around 520–640 nm, and large changes in its absorption spectra upon addition of Na+, with a log βNa of 1.25 (±0.05) and a pKa of 3.9. In 100% water the sensitivity of 2 for Na+ was somewhat lower with a log βNa of 0.8 (±0.05). The crystal structure of 2, and its corresponding protonated form (2·H+) were obtained, showing 2 in its trans conformation with the crown ether moiety at a 75° angle to the plane of the chromophore. These results, in conjunction with 1H NMR measurements of 2, and UV–VIS measurements of the ion receptor 3, suggest that upon complexation of Na+, the 2′-methoxy group of the crown receptor participates in the Na+ complexation through chelation to the Na+ ion. We propose that this interaction forces the amine moiety of the crown ether to twist out of the plane of the chromophore, inducing loss of conjugation which gives rise to large Na+-induced spectral changes in the absorption spectra, which are most noticeable for 2.

The reaction between [{(η5-C5Me4H)RhX2}2] and (C6F5)2PCH2CH2P(C6F5)2 (dfppe) proceeds in refluxing benzene via cleavage of two CF bonds and CH bonds of adjacent methyl groups and formation of two CC bonds to yield selectively the asymmetric cation [{η5,η1,η1-C5HMe2-3,4-[CH2-2-C6F4P(C6F5)CH2]2-1,2}RhX]+. The selectivity for X=Cl was determined to be >90%. Treatment of [(η5-C5Me4H)RhCl(dfppe)]BF4 with proton sponge afforded [{η5,η1,η1-C5HMe2-3,4-[CH2-2-C6F4P(C6F5)CH2]2-1,2}RhCl]BF4 exclusively. The regioselectivity displayed by these reactions is in stark contrast to that in the reaction between [(Cp*RhX2)2] and dfppe, and that between [Cp*RhCl(dfppe)]+ and proton sponge, in which CH bonds of methyl groups in a 1,3 disposition are cleaved to yield the cation [{η5,η1,η1-C5Me3[CH2-2-C6F4P(C6F5)CH2]2-1,3}RhX]+ exclusively. The structure of [{(η5-C5Me4H)RhCl2}2] has been determined by single-crystal X-ray diffraction.

The azo dye based chemosensor 2 displays extremely good sensitivity and selectivity for Na+ over other physiologically important alkali and alkali earth metal ions in the 0.3–1.0×10−4 M concentration range as well as being pH independent above pH 3.9. This sensitivity coincides with the Na+ concentration range found in blood. The sensor exhibits almost 110 nm hypsochromic shift in the absorption spectrum upon Na+ detection, with a strong colour change from red to yellow in aqueous solution which is clearly visible to the naked eye even at low concentrations.

Thermal [2,3]-sigmatropic rearrangements of allyltetronates proceed via 3-(spirocyclopropyl)dihydrofuran-2,4-diones; in some cases these could be isolated and their cyclopropane rings stereoselectively opened with alcohols or water to give 3-(β-syn-alkoxy)tetronic acids. Treatment of a 5,5-disubstituted benzyltetronate with LDA also produced a 3-substituted tetronic acid by an anionic [1,3]-rearrangement.

[M2L3] coordination cages and linear [M2L3]∞ polymers of the rigid, bridging diphosphines bis(diphenylphosphino)acetylene (dppa) and trans-1,2-bis(diphenylphosphino)ethylene (dppet) with silver(I) salts have been investigated in the solution and solid states. Unlike flexible diphosphines, 1:1 dppa/AgX mixtures do not selectively form discrete [Ag2(diphos)2(X)2] macrocycles; instead dynamic mixtures of one-, two- and three-coordinate complexes are formed. However, 3:2 dppa/AgX ratios (X=SbF6, BF4, O3SCF3 or NO3) do lead selectively to new [M2L3] triply bridged cage complexes [Ag2(dppa)3(X)2] 1 a–d (X=SbF6a, BF4b, O3SCF3c, NO3d), which do not exhibit Ag−P bond dissociation at room temperature on the NMR time scale (121 MHz). Complexes 1 a–d were characterised by X-ray crystallography and were found to have small internal cavities, helical conformations and multiple intramolecular aromatic interactions. The nucleophilicity of the anion subtly influences the cage shape: Increasing nucleophilicity from SbF6 (1 a) through BF4 (1 b) and O3SCF3 (1 c) to NO3 (1 d) increases the pyramidal distortion at the AgP3 centres, stretching the cage framework (with Ag⋅⋅⋅Ag distances increasing from 5.48 in 1 a to 6.21 A in 1 d) and giving thinner internal cavities. Crystal packing strongly affected the size of the helical twist angle, and no correlation between this parameter and the Ag–Ag distance was observed. When crystalline 1 c was stored in its supernatant for 16 weeks, conversion occured to the isostoichiometric [M2L3]∞ coordination polymer [Ag(dppa)2Ag(dppa)(O3SCF3)2]∞ (1 c′). X-ray crystallography revealed a structure with ten-membered Ag2(dppa)2 rings linked into infinite one-dimensional chains by a third dppa unit. The clear structural relationship between this polymer and the precursor cage 1 c suggests a novel example of ring-opening polymerisation. With dppet, evidence for discrete [M2L3] cages was also found in solution, although 31P NMR spectroscopy suggested some Ag−P bond dissociation. On crystallisation, only the corresponding ring-opened polymeric structures [M2L3]∞ could be obtained. This may be because the greater steric bulk of dppet versus dppa destabilises the cage and favours the ring-opening polymerisation.

Formal [4+2] cycloaddition of cyclic enamides with imines derived from aromatic amines gave the 4-arylhexahydropyrroloquinoline skeleton in one step as mixtures of diastereoisomers. Aromatic imines derived from formaldehyde and methylglyoxalate also participated in this chemistry, with the latter favouring formation of the endo -cycloadduct. The cycloadducts derived from methylglyoxalate were unstable and fragmented to give highly substituted quinolines under both neutral and basic conditions. Imines derived from 3-cyanoacrolein also underwent cycloaddition and gave an advanced potential precursor to martinellic acid, albeit with poor diastereoselectivity.

X-ray reflectivity measurements in air of thin films of 1-alkyl-3-methylimidazolium salts in the liquid, liquid crystalline and solid states supported on Si(111) are described. The films show Bragg features in both liquid crystalline and solid phases, but only after an initial annealing cycle. Kiessig fringes are observed only for the 1-octadecyl-3-methyl-imidazolium hexafluorophosphate films and, following analysis using Parratt32, a bi-layer model is proposed whereby the molecules are orientated with ionic groups at both salt-air and salt-silicon interfaces.

Self-assembly of the tetradentate ligand bis(N-salicylidene-4,4′-diaminodiphenyl)methane, (H2L), around Co(II) and Cu(II) gives rise to the dinuclear double helicates [Co2L2]·1.7CH2Cl2·0.6H2O, (1) and [Cu2L2]·CH2Cl2 (2), which have been characterised by a single crystal X-ray diffraction study. Complexes 1 and 2 are structurally similar with two four coordinate metal centres in slightly distorted tetrahedral geometries in 1 and severely distorted tetrahedral geometry in 2. The different geometric preferences of Co(II) (tetrahedral) and Cu(II) (square planar) contort the ligands such that extended planarity is absent in 1 whilst present in 2. This distortion results in a tighter helical twist in 1 compared with 2, which consequently has a larger metal–metal separation. Complexes 1 and 2 each exhibit three-dimensional supramolecular entanglement brought about by elaborate inter-molecular π⋯π (face-to-face) and C–H⋯π interactions.

Monomeric ruthenium(II) complexes [Ru(L)3]2+ containing unsymmetric bipyridine ligands [Where L = 5-methyl-2,2′-bipyridine (L1), 5-ethyl-2,2′-bipyridine (L2), 5-propyl-2,2′-bipyridine (L3), 5-(2-methylpropyl)-2,2′-bipyridine (L4), 5-(2,2-dimethylpropyl)-2,2′-bipyridine (L5) or 5-(carbomethoxy)-2,2′-bipyridine (L6)] have been studied and the meridional and facial isomers isolated by the use of cation-exchange column chromatography (SP Sephadex C-25) eluting with either sodium toluene-4-sulfonate or sodium hexanoate. The relative yield of the facial isomer was found to decrease with increasing steric bulk, preventing the isolation of fac-[Ru(L5)3]2+. The two isomeric forms were characterized by 1H NMR spectroscopy, with the complexes [Ru(L1–3)3]2+ demonstrating an unusually large coupling between the H6 and H4 protons. Crystals suitable for X-ray structural analysis of [Ru(L1)3]2+ were obtained as a mixture of the meridional and facial isomers, indicating that separation of this isomeric mixture could not be achieved by fractional crystallisation. The optical isomers of the complex [Ru(L3)3]2+ were chromatographically separated on SP Sephadex C-25 relying upon the inherent chirality of the support. It is apparent that chiral interactions can inhibit geometric isomer separation using this technique.

1-Alkyl-3-methylimidazolium tetrachloropalladate(II) salts ([Cn-mim]2[PdCl4], n = 10, 12, 14, 16, 18) containing a single, linear alkyl-chain substituent on the cation have been synthesised and their behaviour characterised by differential scanning calorimetry, polarising optical microscopy and small-angle X-ray scattering. The salts display thermotropic polymorphism, exhibiting both crystal–crystal transitions and, for n = 14–18, the formation of a thermotropic smectic liquid crystalline phase.

Protonation of 2,3-dipyridin-2-ylquinoxaline 1 results in a significant change in the conformation of the molecule as revealed by 1H NMR and optical spectroscopies and by single crystal X-ray diffraction studies performed upon the product, 2-(3-pyridin-2-ylquinoxalin-2-yl)pyridinium hexafluorophosphate, 2. A further consequence of protonation is that the electronic properties of 2 are altered in such a way as to produce a luminescent compound, the luminescence of which is quenched by a variety of biologically and commercially relevant anions.

The syntheses and crystal structures of four cocrystals; 2-pyridone fumaric acid (2/1), 2-pyridone meso -2,3-dibromosuccinic acid (2/1), 5-chloro-2-pyridone adipic acid (2/1) and 6-methyl-2-pyridone ( S )-malic acid (2/1), are reported. The competition between two self- and mutually-complementary hydrogen-bond moieties (carboxylic acid and 2-pyridone) are examined and compared with results obtained from an earlier study of 2-pyridone and unsubstituted aliphatic dicarboxylic acids.

Reaction of 2-diazo-1,3-diketones with titanocene precursors can produce five-, six- or seven-membered 1-titana-2,n-diheterocyclic complexes with different coordination modes: whereas reaction with dicarbonyltitanocene is fast and furnishes either five-membered titanaoxazacycles or CC coupled seven-membered dioxochelates, decamethyltitanocene dicarbonyl reacts sluggishly to give a novel heteroleptic, trigonal-bipyramidal oxygen bridged Ti 5 O 6 -cluster containing six unsymmetric six-membered titanadioxacyclic ligands.

Several novel thiazoles with side chains derived from natural amino acids and a dipeptide have been synthesised from N-protected α-amino glyoxals and cysteine.

The reaction between [(η 5 -C 5 Me 4 H)RhBr(μ-Br)] 2 and (C 6 F 5 ) 2 PCH 2 CH 2 P(C 6 F 5 ) 2 proceeds in refluxing benzene via the cleavage of two CF and CH bonds and the formation of two CC bonds to give the unexpected asymmetric compound [{η 5 -C 5 HMe 2 -3,4-[CH 2 C 6 F 4 P(C 6 F 5 )CH 2 ] 2 -1,2}RhBr]Br with high selectivity. The formulation has been confirmed by single-crystal X-ray diffraction.

Selective C- over O-/N-acylation of acyclic, carbocyclic and heterocyclic carbonyl compounds bearing active α-CH groups is described. β-Ketoesters give the corresponding α-acylylidic derivatives in good yields. Likewise, tetronic acids and 4-hydroxycoumarins furnish the respective 3-acylylidic derivatives, and pyrazol-5-ones exclusively yield the corresponding 4-acylylidic compounds despite the possibility of tautomerism. X-Ray single crystal structure and NMR analyses of the product tricarbonyl ylides are presented and structure–reactivity interdependencies are discussed. As a rule, compounds with wide-spread conjugation of the π-system like 9/13 do not readily undergo Wittig olefination. Acylylides 11 with separated β-keto moieties react normally.

A series of N-protected α-amino diazoketones has been prepared from L-amino acids and dipeptides and used as precursors in the synthesis of novel N-protected α-amino glyoxals via oxidation with distilled dimethyldioxirane (DMD) in acetone. The glyoxals have been converted, without purification, into enantiopure imines, pyrazines, quinoxalines, and pyrido[2,3-b]pyrazines via condensation with the appropriate amine or diamine. The molecular structure of the pyrido[2,3-b]pyrazine derived from N-Cbz-L-phenylalanine has been determined by X-ray analysis.

The reaction between [(η5-C5Me4H)RhCl(μ-Cl)]2 and the phosphines PPh2R (R=Ph or C6F5) or cyclohexylisonitrile yields the complexes (η5-C5Me4H)RhCl2L (1, L=PPh3; 2, L=PPh2(C6F5); 3, L=CNC6H11). The structures of complexes 1 and 2 have been determined by single-crystal X-ray diffraction. Both exhibit three-legged piano stool geometry about the rhodium atom. Unlike the structures of (η5-C5Me5)RhCl2L complexes, the rhodium atoms of 1 and 2 do not lie on axes normal to the C5 centroids, but are displaced towards the CH carbon atoms. Treatment of 1 with cyclohexylisonitrile or 3 with PPh2(C6F5) in the presence of NaBF4 yield the chiral-at-metal salts [(η5-C5Me4H)RhCl(PPh2R)(CNC6H11)]+·BF4− as racemic mixtures. The bis(isonitrile) complex, [(η5-C5Me4H)RhCl(CNC6H11)2]+·BF4−, is formed similarly from 3. Treatment of [(η5-C5Me4H)RhCl(μ-Cl)]2 with dppe in the presence of NaBF4 yields [(η5-C5Me4H)RhCl(dppe)]+·BF4−.

Analysis of the title complex, K2[Fe(CN)4(C10H8N2)].2.5H2O, shows that the asymmetric unit contains two [Fe(bpy)(CN)4]2− units, four K+ ions and five water molecules. There is extensive hydrogen bonding within the structure and, as expected, all hydrogen-bond donors and acceptors are involved in hydrogen bonding, resulting in a complex three-dimensional network. The water molecules and K+ ions occupy three different channels in the framework created by the packing of the [Fe(bpy)(CN)4]2− units.

The conformation of a p-tert-butylcalix[4]arene with four (R)-1(1-phenyl-ethyl)carbamic acid ethoxyester residues on the lower rim has been investigated by X-ray diffraction and 1H NMR analysis. The molecule adopts a pinched cone conformation in the solid state with intramolecular hydrogen bonding between the carbonyl groups and the nitrogen atoms of proximal carbamate podands. The NMR evidence indicates that this conformation persists in solution at room temperature. At temperatures >80°C the NMR spectrum is that of a time-averaged C4v symmetrical cone conformation.

An examination of the crystal structures of four compounds, 5-amino iso-phthalic acid hemihydrate (monoclinic, P21/n, a = 8.142 (2), b = 17.444 (3), c = 11.140 (2) A, β=94.19 (3)°, Dc =1.601 g cm−3, Z=8, Rw 2 = 0.106 for 1401 unique reflections), piperazinium(2+) 5-amino iso-phthalate (monoclinic, P21/c, a = 11.820 (2), b = 9.516 (2), c = 12.618 (3) A, β = 116.70 (3)°, Dc = 1.400 g cm−3, Z = 4, Rw 2, = 0.104 for 2222 unique reflections), 2-chloro-benzylammonium 2-carboxylate-6-carboxylic pyridine (monoclinic, P21/c, a = 22.391 (2), b = 9.322 (3), c=13.274 (2) A, β=92.567 (11), Dc =1.482 g cm−3, Z=8, Rw 2 = 0.113 for 3610 unique reflections), and 3-fluoro-benzylammonium 2-carboxylate-6-carboxylic pyridine hydrate (monoclinic, P21/c, a = 9.862 (2), b = 13.246 (3), c = 21.153 (4) A, β = 98.00 (3), Dc =1.463 g cm−3, Z = 8, Rw 2 = 0.154 for 2552 unique reflections), has identified a robust hydrogen-bonded, ribbon-like motif, generated by the geometric fit and hydrogenbond complementarity of the [— COO...

The new fluorine-containing diphosphine (C6H3F2-2,6)2PCH2CH2P(C6H3F2-2,6)2 I has been prepared and structurally characterized by single-crystal X-ray diffraction. The reaction between [{RhCl(µ-Cl)(η5-C5Me5)}2] and I in refluxing benzene yielded the cationic species [RhCl{η5-C5Me3[(2-CH2C6H3F-6)P(C6H3F2-2,6)CH2]2-1,3}]+, which was characterized as the BF4– salt 1. The reaction involved the regiospecific activation of two C–F bonds and two C–H bonds and the formation of two C–C bonds. In contrast, the reaction between [{IrCl(µ-Cl)(η5-C5Me5)}2] and I did not involve C–F bond activation, but resulted in the formation of the dinuclear complex [{IrCl2(η5-C5Me5)[P(C6H3F2-2,6)2CH2]}2] 2, the characterization of which was confirmed by the synthesis of the (C6F5)2PCH2CH2P(C6F5)2 analogue [{IrCl2(η5-C5Me5)[P(C6F5)2CH2]}2] 3. The complexes [MCl{(C6H3F2-2,6)2PCH2CH2P(C6H3F2-2,6)2}(η5-C5Me5)]+BF4– (M = Rh 4 or Ir 5), unlike their (C6F5)2PCH2CH2P(C6F5)2 analogues, did not undergo C–F and C–H bond activation and C–C bond formation on thermolysis. The structures of complexes 2–4 have been determined by single-crystal X-ray diffraction.

The crystal structures of four compounds from a family of commonly used molecular building blocks of nonlinear optical materials, aminonitropyridines, have been determined. The structures of 2-amino-5-nitropyridine 1, 2-amino-5-nitropyridine monohydrate 2, and of two new polymorphs of 2-amino-3-nitropyridine 3,4, are all stabilised by a combination of hydrogen bonds (including C–H‥X interactions) and dispersive and electrostatic interlayer interactions. The balance between these intermolecular forces, and the way in which they influence the packing of these materials, are discussed.

An examination of the crystal structures of di-hydroxy malonic acid 1 (P21/na = 5.384(2), b = 6.268(2), c = 14.354(8) A, β = 103.57(3)°) and N-ethylbenzylammonium di-hydroxy hydrogenmalonate 2 (P212121a = 13.373(2), b = 15.342(4), c = 18.741(4) A,) has highlighted the influence of directional O–H···O interactions in the assembly of hydroxy-substituted dicarboxylic acids. The complementarity of carboxylic and hydroxy groups in 1 creates a very dense 3-D structure (Dc = 1.919 g cm−3) through four O–H···O hydrogen bonds. In 2, the anions form infinite, spiraling chains created by head-to-tail O–H···O hydrogen bonds. Neighbouring chains are crosslinked into a complex 3-D anionic network with channels parallel to a and b. The cations are positioned within these channels and held in place via two N–H···O interactions.

The reaction between [{(η5-C5Me5)RhCl(μ-Cl)}2] and (C6F5)2PCH2P(C6F5)2 in refluxing benzene yields the singly linked complex [{(η5,κP-C5Me 4CH2C6F4-2-P(C6F5)CH2P(C6F5)2)}RhCl2] in which only one phosphorus atom is coordinated to the rhodium.

1-Hydroxy-1,2-benziodoxol-3(1H)-one 1-oxide prepared by oxidation of o-iodobenzoic acid with potassium bromate forms either a microcrystalline powder, a macrocrystalline material, or a mixture of both forms. This difference in physical form is the source of the difficulty in reproducibly converting 1-hydroxy-1,2-benziodoxol-3(1H)-one 1-oxide to the corresponding I-triacetoxy derivative. A simple method is given for conversion of crystalline 1-hydroxy-1,2-benziodoxol-3(1H)-one 1-oxide to the more reactive powder form. The microcrystalline powder and macrocrystalline material are characterised by X-ray diffraction.

Hydrogen l -malate anions can be utilized in the crystal engineering of ionic materials as a means of providing structural consistency and rigidity by creating infinite anionic layers held together by directional O-H···O hydrogen bonds. The syntheses and crystal structures of three new organic hydrogen l -malate salts, [AH][Hmal], are described (where A = (4-methyl)benzylamine, (4-chloro)benzylamine and (3-chloro)benzylamine). In each case, the anions create extended architectures (infinite layers) via O-H···O interactions. Each cation is then attached to one side of the anionic layer via three N-H···O interactions. The layers are stacked in an AABBAABB… fashion with both anionic and cationic sheets arranged in pairs throughout each crystal. The structural influence of the cations, and the importance of the directionality and selectivity of hydrogen bonds in the construction of extended “building blocks”, is discussed.

To examine packing preferences and hydrogen-bond patterns in organic l-malate salts [AH2][mal] or [AH]2[mal] (where A = amine), the syntheses and crystal structures of six new salts, bis(4-chlorobe...

In order to examine the possibilities of using the oxamate anion, [OOCCONH2]-, as a versatile building block of low-dimensional, hydrogen-bonded scaffolding, the preferential assembly patterns displayed by this anion were identified using X-ray single-crystal data for a sequence of simple oxamate salts. Several new compounds were synthesized, and the crystal structures of six materials are presented: piperidinium oxamate (1), 2-amino-5-nitropyridine 2-amino-5-nitropyridinium oxamate (2), imidazolium oxamate (3), (4-chlorobenzyl)ammonium oxamate (4), (3-chlorobenzyl)ammonium oxamate (5), and potassium oxamate monohydrate (6). The oxamate anion acts as a building block of either 1-D (ribbons or ladders) or 2-D (layers) motifs. These architectures (generated by NH···O hydrogen bonds) are the result of the selectivity of complimentary hydrogen-bond sites of the anion. However, the type of network adopted is also influenced by cation−anion interactions, and the role of the physical−chemical characteristics of...

Chiral dienamides, derived from chiral amines and oxazolidinones, react with electron deficient dienophiles to give amino-cyclohexenes with good to excellent de's.

Complexes of the type trans-[CrCl2(RNH2)4]Cl (R = Et, nPr, nBu) are readily formed from [CrCl3(thf)3] and four equivalents of the amine in tetrahydrofuran (thf). The structure of trans-[CrCl2(cPrNH2 BF4·H2O (tricline, P1, α = 5.828(3), b = 10.030(10), c = 10.403(4) A, α = 73.34(6), β = 89.37(3), γ = 87.78(7), V = 582.1(7) A3, Z - 1) ahs been determined by single crystal X-ray diffraction. The two Cr bonds are approximately equivalent (CrCl(1) = 2.325(3), CrCl(2) = 2.326(3)) and two of the (cis) nPrNH2 ‘arms’ are above and two below teh Cr(N)4 plane. The rates of loss of the first chloro ligand from trans-[CrCl2(RNH2)4]+ (R = Et, nPr, nBu) are about 16 times slower than that for R = H. Spectrophotometrically determined kinetic parameters (0.05 M HNO3, 25°C) are R = H: 106 k (s−1= 45.9, ΔH≠ (kJmol−1) = 94.9, ΔS≠ (JK−1 mol−) = − 10; R = Et: 106 k = 2.88, ΔH≠ = 116, ΔS≠ = + 39; R = nPr: 106 k = 6.70, ΔH≠ = 101, ΔS≠ = − 6, R = nBu: 106 k = 4.90, ΔHsu≠ = ΔS≠ = +3 Hg2+-assisted chloride release kinetics for the first step in the aquation of several of several trans-[CrCl2 (N)4]+ systems have been measured in 50:50 dmf:aq. HClO4 (I = 0.5 M). The activation entropy data suggest that the thermal aquation process for trans-[CrCl2(N)4]+ are move widely spread across the interchange mechanistic spectrum than those for the analogous Co(III) systems.

The seven-member alicyclic secondary amine, azepane, has been used as starting material to synthesise a new family of room temperature ionic liquids. Such useful transformations of this coproduct of diamine production processes, generated in large amounts in the polyamide industry, would mitigate its disposal, which usually involves combustion. Reaction of azepane with 1-bromoalkanes or 1-bromoalkoxyalkanes produced the corresponding tertiary amines with good selectivity; further quaternisation reactions with the appropriate methylating agents yielded quaternary azepanium salts, [Rmazp]X (R = alkyl or alkoxyalkyl; X- = I - , [CF3 CO2 ] - or [OTf]- ; Tf = (tri¿uoromethyl)sulfonyl). Analogous [NTf2 ] - salts have also been produced by metathetic reactions. Liquid temperature ranges are signi¿cantly affected by the nature of the anion and the substituents on the azepanium cation core; for example, [CF3 CO2 ] - or [OTf]- salts based on cations with alkyl substitution are solids, whereas those with alkoxyalkyl substitution are liquids at ambient temperature. The crystal structures of [C4 mazp][CF3 CO2 ], [C4 mazp]I and [C6 mazp][NTf2 ] (C4 = butyl, C6 = hexyl) are reported. The effects of the structural features of cations and anions on density, viscosity and conductivity data are discussed. The presence of ether linkages in the cationic side chains causes a marked decrease in viscosities and an increase in conductivities. Cyclic voltammetry showed that azepanium ionic liquids exhibit extremely wide electrochemical windows, thus becoming promising and safe alternatives to electrolytes based on volatile organic compounds

X-Ray crystal structure determinations have been made for the fac octahedral complexes [InCl3(dmf)3]1, [InCl3(dma)3]2 and [{InCl3(PhCHO)3}2]·PhCHO 3, from dimethylformamide (dmf), dimethyl-acetamide and benzaldehyde and the trigonal-bipyramidal complex [InCl3(PhCOMe)2]4 from acetophenone. The average In–O bond length for 3 is ca. 0.07 A greater than for 1 or 2. In 4, In–O is 0.07 A longer than that known for [InCl3(tmu)2] from tetramethylurea (tmu). An extension of the comparison to structures involving other ligands shows there to be a general correspondence between In–O bond lengths and ligand donor values. By contrast with the weak co-ordination of aldehydes and ketones, co-ordination of an amide is enhanced through polarisation. In the crystal of 3, individual [InCl3(PhCHO)3] molecules are paired, almost centrosymmetrically, with intermeshing of their PhCHO ligands.

The tricyclic core of martinelline and martinellic acid was rapidly assembled utilising an imino Diels–Alder reaction of an imine derived from cinnamaldehyde with a cyclic enamide. The cycloaddition was completely regioselective though the exo – endo selectivity was poor. These diastereoisomers were readily separated by flash chromatography and the relative stereochemistry of the exo -isomer confirmed by single crystal X-ray crystallography. This intermediate was converted to the central core of the aforementioned alkaloids in five additional synthetic operations.

The endocyclic CC bond of 3-allyltetronic acid 1 can be selectively oxidised with dimethyldioxirane to give 3-allyl-3-hydroxydihydrofuran-2,4-dione 2 while 3-exo-alkylidenedihydrofuran-2,4-diones 9 are rapidly autooxidised to furnish the spirotricyclic hemiketal endoperoxide lactones 10.

A convenient synthetic route to hybrid cyclopentadienyl–phosphine complexes is demonstrated by the high yield synthesis of the complex [RhCl{η5,η1,η1-C5Me4CH2C6F4P(C6F5)C6H4SMe}][BF4].

Chiral dienamides, derived from chiral amines and oxazolidinones, react with electron deficient dienophiles to give amino-cyclohexenes with good to excellent de's.

In a search for 3–5 µm lasing materials, crystals Of AlBr6Sb are isolated from a phosphorus tribromide–aluminium tribromide–antimony tribromide (PBr3–AlBr3–SbBr3) solution: this solid contains infinite chains of alternating [SbBr2]+ cations and [AlBr4]+ anions, linked by weak coordinate bonds, and represents the first structure containing the dibromostibinium(III) cation.

Enaminones react with itaconic anhydride in methylene chloride at room temperature to give exocyclic enamides as the major products. These can be readily equilibrated to the thermodynamically more stable endocyclic enamides. In substrates where the exocyclic isomer could not be formed only intractable materials were produced from this reaction. An intermediate in this two step process was detected and identified by proton and 13C NMR spectroscopy. In two cases chiral enaminones were employed and the relative stereochemistry at the new chiral centre in the product was established by a crystal structure of compound 27.

Several novel thiazoles with side chains derived from natural amino acids and a dipeptide have been synthesised from N-protected α-amino glyoxals and cysteine.

Formal [4+2] cycloaddition of cyclic enamides with imines derived from aromatic amines gave the 4-arylhexahydropyrroloquinoline skeleton in one step as mixtures of diastereoisomers. Aromatic imines derived from formaldehyde and methylglyoxalate also participated in this chemistry, with the latter favouring formation of the endo -cycloadduct. The cycloadducts derived from methylglyoxalate were unstable and fragmented to give highly substituted quinolines under both neutral and basic conditions. Imines derived from 3-cyanoacrolein also underwent cycloaddition and gave an advanced potential precursor to martinellic acid, albeit with poor diastereoselectivity.

Thermal [2,3]-sigmatropic rearrangements of allyltetronates proceed via 3-(spirocyclopropyl)dihydrofuran-2,4-diones; in some cases these could be isolated and their cyclopropane rings stereoselectively opened with alcohols or water to give 3-(β-syn-alkoxy)tetronic acids. Treatment of a 5,5-disubstituted benzyltetronate with LDA also produced a 3-substituted tetronic acid by an anionic [1,3]-rearrangement.

The tricyclic core of martinelline and martinellic acid was rapidly assembled utilising an imino Diels–Alder reaction of an imine derived from cinnamaldehyde with a cyclic enamide. The cycloaddition was completely regioselective though the exo – endo selectivity was poor. These diastereoisomers were readily separated by flash chromatography and the relative stereochemistry of the exo -isomer confirmed by single crystal X-ray crystallography. This intermediate was converted to the central core of the aforementioned alkaloids in five additional synthetic operations.

Allyl tetronates 3 can be selectively converted either (in acetonitrile) into Claisen-rearranged 3-allyltetronic acids 5 or (in toluene) into novel Claisen−Conia-rearranged 3-(spirocyclopropyl)dihydrofuran-2,4-diones 6, featuring up to three new stereogenic centres. The mechanism and the stereochemistry of this process is discussed and an X-ray crystal structure of one of the two diastereoisomers of (±)−6c is presented.