bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis, IR and 119mSn Mössbauer spectra of di‐ and tri‐organotin molybdates
Authors: Smith Peter J. , Patel Bhagwati N.
Published: September 2010

11 organotin molybdates, R2SnMoO4, where R = Me (1), Et (2), Bu (3) and Oct (4), (R3Sn)MoO4, where R = Bu (5), Ph (6), c‐C6H11 (7) and PhMe2CCH2 (8), and (R3Sn)(R′3Sn)MoO4, where R = Bu, R′ = Ph (9) or c‐C6H11 (10); R = Ph, R′ = c‐C6H11 (11), have been synthesised and their structures in the solid state investigated by 119mSn Mössbauer and IR spectroscopy. The Mössbauer spectra at 80 K are in accord with the tin atoms in the dialkyltin molybdates occupying a trans‐R2SnX4 octahedral geometry, and those in the bis(triorganotin) molybdates adopting a trans‐R3SnX2 trigonal bipyramidal stereochemistry, due to intermolecular bridging by the MoO4 ligands.

The unsymmetrical bis(triorganotin) molybdates are the first examples of stable triorganotin compounds containing R3SnX and R′3SnX groups (X = electronegative radical) in the same molecule.
A nickel‐carbene complex as an intermediate in the polymerization of isocyanides
Authors: Kamer Paul C. J. , Nolte Roeland J. M. , Drenth Wiendelt
Published: September 2010

An intermediate in the polymerization of isocyanides, catalysed by nickel(II), has been isolated and characterized. The polymerization starts by nucleophilic attack of (S)‐(‐ )‐(1‐phenylethyl)amine on the terminal carbon atom of a coordinated isocyanide of tetrakis(tert‐butyl isocyanide)nickel(II) perchlorate. The resulting intermediate was isolated and shown to be a nickel‐carbene complex: Ni(CN‐t‐C4H9)3 [C[NHCH(CH3)C6H5]NH‐t‐C4H9](ClO4)2. In solution, the carbene complex appears to have three conformations. The effect of these conformations on the enantioselective polymerization of isocyanides is discussed.
The phthalation of 2‐amino‐2‐deoxy‐D‐glucose and N‐methyl‐1‐amino‐1‐deoxy‐D‐glucitol; conversion of the products to organotin derivatives. A ready migration of acetyl from oxygen to nitrogen under neutral conditions
Authors: Patel Atula , Poller Robert C.
Published: September 2010

N‐Phthalation of 2‐amino‐2‐deoxy‐D‐glucose was followed by replacement of the acidic proton by tributyl‐ and triphenylstannyl groups. A similar reaction with 1‐(methylamino)‐1‐deoxy‐D‐glucitol failed and successive treatment with benzyl chloroformate and acetic anhydride followed by catalytic hydrogenation showed that a 1,4 O → N acetyl migration had occurred. Phthalation and stannylation succeeded under different conditions.
Les (triméthylsilyl)bicyclo[n.1.0]‐alcènes, nouveaux silylcyclopropanes bicycliques fonctionnels
Authors: Grignon‐Dubois M. , Dunoguès J. , Ahra M.
Published: September 2010

Nous proposons une méthode de synthèse de bicyclo[n.1.0]‐alcènes siliciés originaux, de mise en œuvre simple et rapide. Elle permet d'accéder dans de bonnes conditions aus deux isomères endo et exo monosiliciés ainsi qu'aux analogues gem‐disiliciés.

Le comportement de ces dérivés vis‐á‐vis d'acides [HCl, (CH3COOH)2BF3] montre que la taille du grand cycle et la position relative de la double liaison par rapport au cyclopropane, détermine le site de l'attaque électrophile: selon les cas, elle intervient sur la double liaison ou sur le cycle á 3 chaînons. Ces résultats ouvrent des perspectives nouvelles pour la fonctionalisation des cyclènes via la cyclopropanation.
Palladium(0)‐catalyzed isomerization of α,β‐epoxy ketones to β‐diketones
Authors: Suzuki M. , Watanabe A. , Noyori R.
Published: September 2010

In the presence of catalytic amounts of tetrakis(triphenylphosphine)palladium(0) and 1,2‐bis(diphenylphosphino)ethane, α,β‐epoxy ketones isomerize to the corresponding β‐diketones in high yields. Both open‐chain and cyclic substrates can be used. Possible reaction mechanisms are discussed.
Reactions of monoazadienes with metal carbonyl complexes.II. REACTIONS OF N‐ALKYL‐(E)‐CROTONALDIMINE WITH Ru3(CO)12. THE X‐RAY CRYSTAL STRUCTURE OF Ru3(CO)6(CH3‐CCH‐CHN‐C3H7‐i)2, AN ACYCLIC CLUSTER WHICH IS ISOLOBALLY RELATED TO RUTHENOCENE
Authors: Mul Wilhelmus P. , Elsevier Cornelis J. , Vrieze Kees , Smeets Wilberth J. J. , Spek Anthony L.
Published: September 2010

The reaction of Ru3(CO)12 with CH3‐CHCH‐CHN‐C3H7‐i in refluxing heptane yields RU3(CO)6(CH3‐CCH‐CHN‐C3H7‐i)2 in two stereoisomeric forms, together with several other products. One of the stereoisomers was purified. The X‐ray crystal structure shows an unprecedented bent trinuclear metal core with two metal‐metal bonds. The two γ‐metallated monoazadienyl ligands each donate 7e to the acyclic cluster.
Synthesis and conformation of 1‐(3′‐C‐methyl‐2′‐deoxy‐β‐D‐xylofuranosyl)uracil and 9‐(3′‐C‐methyl‐2′‐deoxy‐β‐D‐xylofuranosyl)adenine; two novel sugar‐methylated nucleoside analogues
Authors: Koole L. H. , Moody H. M. , Buck H. M. , Grouiller A. , Essadiq H. , Vial J.‐M. , Chattopadhyaya J.
Published: September 2010

The preparation and high‐resolution 1H NMR conformational analysis of the two novel nucleoside analogues, 1‐(3′‐C‐methyl‐2′‐deoxy‐β‐D‐xylofuranosyl)uracil (compound 1) and 9‐(3′‐C‐methyl‐2′‐deoxy‐β‐D‐xylofuranosyl)adenine (compound 2), are described. Compounds 1 and 2 show a pronounced preference for the north conformation of the sugar ring. The north conformation corresponds with a sterically favoured equatorial location of the methyl group. The C4′ ‐ C5′ conformation in 1 and 2 is predominantly γt (trans orientation of O5′ and C3′). The configuration at C3′ in 1 and 2 was corroborated via a one‐dimensional NOE experiment. The structure of compound 1 (originally assigned as having the C3′‐methyl group on the β‐face of the furanosyl moiety) is revised on the basis of these data.
Amine catalyzed ring opening of (2 + 2) cycloadducts derived from enamines of cyclic ketones and methyl propynoate
Authors: Egberink R. J. M. , Verboom W. , Benders P. H. , Reinhoudt D. N. , Harkema S.
Published: September 2010

The (2 + 2) cycloadducts 3, 6, 10 and 13, derived from pyrrolidine enamines of cyclic ketones and methyl propynoate 2, react, under the influence of pyrrolidine via the α‐[(1‐pyrrolidinyl)methylene]cycloalkeneacetates (Z)‐4, (Z)‐7, (Z)‐11 and (Z)‐14, to give the corresponding E isomers. The structure of (E)‐7 has been unequivocally established by X‐ray analysis. The formation of (E)‐4, (E)‐7, (E)‐11 and (E)‐14 can be explained by the sequence: Michael addition, elimination, conrotatory ring opening, followed by Z/E isomerization. In the cases involving a relatively slow reaction (10, 13) and, in addition, the presence of an excess of pyrrolidine, the enamines 9, 16 and the propenoate 12 could also be detected. The formation of 12 can be rationalized by a Michael addition of pyrrolidine to methyl propynoate (2), formed by a retro (2 + 2) cycloaddition.
Total synthesis of optically active myo‐inositol 1,4,5‐trisphosphate and myo‐inositol 1,3,4,5‐tetrakisphosphate
Authors: Dreef C. E. , Tuinman R. J. , Elie C. J. J. , van der Marel G. A. , van Boom J. H.
Published: September 2010

A convenient approach to the preparation of the title compounds illustrating selective protection, optical resolution and phosphorylation is presented.
Mechanism of electrooxidation of substituted phenols in aqueous solutions: Some podophyllotoxin derivatives as models
Authors: Zuman Peter , Holthuis Joost J. M.
Published: September 2010

Etoposide (1) and teniposide (2) proved to be suitable models for oxidation of phenols, because radicals formed by the one‐electron oxidation of their phenolates do not dimerize. Mechanism (1)‐(6) indicates in which pH range the oxidation occurs in a single two‐electron step and in which in two one‐electron transfers. The phenolates are more easily oxidized than phenols. Due to a rapid formation of the phenolate ions at the electrode surface, its oxidation is preferred even at pH 3, about seven pH units below the pKa value. Phenoxenium ions formed in the two‐electron oxidation eliminate CH3O− ions and form ortho‐quinones.
Diels‐Alder reaction of 6‐demethoxy‐β‐dihydrothebaine with methyl vinyl ketone using microwave heating; preparation and pharmacology of 3‐hydroxy‐α,α, 17‐trimethyl‐6β,14β‐ethenomorphinan‐7β‐methanol, a novel deoxygenated diprenorphine analogue (chemistry of opium alkaloids, part XXV
Authors: Linders J.T.M. , Kokje J.P. , Overhand M. , Lie T.S. , Maat L.
Published: September 2010

Diels‐Alder reaction of 6‐demethoxy‐β‐dihydrothebaine 6 with methyl vinyl ketone (3‐buten‐2‐one) yielded, in a 3:2 ratio, (+)‐7β‐acetyl‐3‐methoxy‐17‐methyl‐6β,14β‐ethenomorphinan‐4‐ol (7) and the novel (+)‐8β‐acetyl‐3‐methoxy‐17‐methyl‐6β,14β‐ethenomorphinan‐4‐ol (8). Performing the reaction in a microwave oven resulted in a faster and cleaner reaction. 1H NMR and mass spectra of 8 were studied and the structure was finally established by single‐crystal X‐ray analysis of its 4‐O‐phenyl ether 13. In contrast to thebaine and 6‐demethoxythebaine, the cyclo‐addition reaction of 6‐demethoxy‐β‐dihydrothebaine with methyl vinyl ketone occurred at the α‐face of the diene system.

Ullmann reaction of 7 with bromobenzene, followed by Grignard reaction with methylmagnesium bromide and removal of the phenoxyl group using sodium in liquid ammonia, afforded the tertiary alcohol 11. O‐Demethylation of 11 by potassium hydroxide in boiling glycol, using microwave heating, afforded (+)‐3‐hydroxy‐α,α,17‐trimethyl‐6β,14β‐ethenomorphinan‐7β‐methanol 12. The structure of 12 was confirmed by 1H NMR and single‐crystal X‐ray analysis. Compound 12 showed morphine‐like activity in the PPQ assay.
The chemistry of D‐gluconic acid derivatives. Part II1: The formation of (R)‐O‐isopropylideneglyceraldehyde from D‐glucono‐1,5‐lactone
Authors: Chittenden Gordon J. F.
Published: September 2010

Reaction of D‐glucono‐1,4‐lactone, obtained from the 1,5‐lactone by a modified procedure, with 2,2‐dimethoxypropane‐tin(II) chloride yields the corresponding 5,6‐O‐isopropylidene derivative. The preparation of the title compound from this acetal by periodate oxidation together with the characterisation of products and intermediates is described.
Tetrahedral intermediates formed during the nucleophilic addition‐elimination reaction of carbonyl‐containing compounds in the gas phase. Part II
Authors: van der Wel H. , Nibbering N. M. M.
Published: September 2010

The structures of adduct ions formed between the nucleophiles HO− and CH3O− and various carbonyl compounds, such as aldehydes, esters and amides, have been probed in the gas phase by studying their proton affinity, collision‐induced dissociation pathways and chemical reactivity, using Fourier‐Transform Ion‐Cyclotron‐Resonance (FT‐ICR) Mass Spectrometry.

Most of the generated adduct ions are shown to have stable, often proton‐bound, loosely associated structures as well as stable, covalently bound, tetrahedral structures.
Sulfonation and sulfation of 1,3‐dihydroxybenzene and its methyl ethers in concentrated sulfuric acid
Authors: Cerfontain Hans , Koeberg‐Telder Ankie
Published: September 2010

The homogeneous sulfonations of 1,3‐dihydroxybenzene (1), its monomethyl (2) and dimethyl ether (3) in concentrated aqueous sulfuric acid at 25°C have been studied and isomer distributions and rate coefficients for the sulfonation of 1–3 and their monosulfonic acids are reported. The initial process, upon dissolution of the reactants, is protonation at C(4) and C(6). The subsequent sulfonation of the symmetrical reactants 1 and 3 yields the 4‐sulfonic acids and that of 2 the 4‐ and 6‐sulfonic acids, the ratio of which is 0.8 + 0.1 at 73.5% H2SO4. The sulfonation of the 4‐sulfonic acid of 1 (1‐4‐S) yields a mixture of 2,4‐ and 4,6‐disulfonic acids, that of 2‐4‐S and 3‐4‐S yields the 4,6‐S2 and that of 2‐6‐S gives a mixture of 2,6‐ and 4,6‐S2. The disulfonic acids 1‐2,4‐S2 and 2‐2,6‐S2 both slowly isomerize to yield the 4,6‐disulfonic acid isomers. At acid concentrations ≥ 82.8% H2SO4, the disulfonic acids of 1 slowly yield 1‐2,4,6‐S3, whereas those of 2 and 3 are not further sulfonated. The absence of 2‐2,4‐S2 from 2‐4‐S and of 2‐2,4,6‐S3 and 3‐2,4,6‐S3 is discussed in terms of conformer populations of the precursory sulfonic acid substrates.
Photochemical reactivities of cyclic α‐phenyl‐β,γ‐enones. Singlet 1,3‐acyl shift, decarbonylation and unquenchable oxa‐di‐π‐methane reactions upon direct irradiation
Authors: Koppes Margareth J. C. M. , Cerfontain Hans
Published: September 2010

The photochemistry of the α‐phenyl‐β,γ‐enones 3–6 has been studied under conditions of direct (λ 300 nm) and triplet‐sensitized irradiation.

Upon direct irradiation, 3 exhibits decarbonylation, a 1,3‐acyl shift (1,3‐AS) and an oxa‐di‐π‐methane (ODPM) rearrangement. Under the same conditions, 4, on the other hand, affords only the ODPM product whereas 5 gives the decarbonylation, 1,3‐AS and ODPM products. The formation of the ODPM product of 5 is efficiently quenched by triplet quenchers in contrast to the ODPM products of 3 and 4, the quantum yields of which are not reduced upon the addition of typical triplet quenchers. Triplet‐sensitized irradiation of 5 leads to the ODPM rearrangement, whereas surprisingly 3 and 4 are unreactive. It is suggested that the ODPM rearrangement, upon direct irradiation of 3 and 4, proceeds from the S2(ππ*) state. The ODPM product formed upon direct irradiation of 5 is thought to be formed from the T1(ππ*) state populated by ISC from the S1(nπ*) state.

Upon direct irradiation, 6 exhibits a reversible 1,3‐AS and in addition ketene formation via an intramolecular 1,5‐H shift. Under conditions of triplet photosensitization, compound 6 appears to be stable.

Given the apparently different photochemical behaviour of these constrained compounds, a general reactivity pattern for the direct and sensitized irradiation cannot be defined.
Preparation of internucleotide phosphate analogues via the corresponding H‐phosphonate diester
Authors: de Vroom E. , Dreef C. E. , van den Elst H. , van der Marel G. A. , van Boom J. H.
Published: September 2010

Silylation of a H‐phosphonate diester with N, O‐bis(trimethylsilyl)acetamide or tert‐butyldimethylsilyl chloride affords 3′,5′‐internucleotidic phosphite triester intermediates. Arbusow reaction of the latter compounds with appropriate halogenides gives the corresponding phosphonate derivatives.
Synthesis of two analogues of a fragment of the complex polysaccharide C substance from Streptococcus pneumoniae type 1
Authors: Hermans J. P. G. , Dreef C. E. , Hoogerhout P. , van der Marel G. A. , van Boom J. H.
Published: September 2010

The syntheses of two (spacer‐containing and choline‐phosphate‐deficient) analogues (12e and 12h, Scheme 2) of a fragment of the C substance from S. pneumoniae type 1 are presented. Starting from 1,6:2,3‐dianhydro‐ß‐D‐talopyranose (la), the “building block” 1‐O‐(3,6‐di‐O‐acetyl)‐2‐azido‐4‐O‐benzyl‐2‐deoxy‐ß‐D‐galactopyranosyl)‐2,3,4‐tri‐O‐benzyl‐D‐ribitol (6b) was obtained in six steps (Scheme 1). A second “building block” (9e), containing a protected propanolamine spacer, was prepared in five steps, starting from 2,3,4,6‐tetra‐O‐acetyl‐α‐D‐glucopyranosyl bromide (7). The building blocks 6b and 9e were coupled (Scheme 2) using bis(1‐benzotriazolyl) 2‐chlorophenyl phosphate (10) to give the fully protected phosphotriester derivative 12a. Complete deprotection of compound 12a via two different routes afforded β‐D‐GalNH2p‐(1 ŕ l)‐ribitol‐5‐phosphate‐6‐β‐D–Glcp‐[1 ŕ O‐(CH2)3‐NH2] (12h, an analogue of structure Ia) and its β‐D‐GalNAcp derivative 12e (corresponding to Ib).
Reactions of the dihydroxybenzenes and their methyl ethers with sulfur trioxide. The effect of initial sulfation on the sulfonation product distribution
Authors: Cerfontain Hans , Coenjaarts Norbert J. , Koeberg‐Telder Ankie
Published: September 2010

The sulfation and sulfonation resulting from the reaction of the dihydroxybenzenes and their mono‐ and dimethyl ethers with SO3 in nitromethane have been studied, and their product distributions are reported. As to the non‐hydroxy‐substituent‐containing substrates, 1,2‐dimethoxy‐benzene (3) yields the 4‐sulfonic acid (3‐4‐S) which, upon further sulfonation, yields a 1:4 mixture of the 3,5‐ and 4,5‐S2. The 1,3‐ (6) and 1,4‐isomer (9) yield initially the 4‐ and 2‐S, respectively, and subsequently exclusively 6‐4,6‐ and 9‐2,5‐S2, respectively.

With the substrates containing one hydroxy substituent, the sulfonation isomer distribution is dependent on the SO3 to substrate ratio if the OH and OMe substituents are in ortho or para orientation, due to increasing sulfonation of the corresponding methoxyphenyl hydrogen sulfate. Thus, 2‐methoxy‐ (2) and 4‐methoxyphenol (8) with one equiv of SO3 at 0°C yield a 3:1 mixture of 2‐4‐S and 2‐5‐S and a 9:1 mixture of 8‐2‐S and 8‐3‐S, respectively, but, with ≥4 equiv of SO3, the former reactant yields only 2‐5‐S and the latter only 8‐3‐S. 3‐Methoxyphenol (5) yields initially a 1:1 mixture of the 4‐ and 6‐sulfonic acid. Further sulfonation yields only 5‐O,4,6‐S3 which slowly cyclizes to the 1,3,2, 4‐benzodioxadithiin 2,2,4,4‐tetraoxide derivative 11.

As to the dihydroxy‐containing substrates, 1,2‐dihydroxybenzene (1) with 1 equiv of SO3 first yields the hydrogen sulfate 1‐O‐S which rearranges to 1‐4‐S; on using an excess of SO3, the eventual product is l‐O(2),4‐S2. Similarly, the 1,4‐isomer (7) with 1 equiv of SO3 yields initially 7‐O‐S which isomerizes to 7‐2‐S. With 6 equiv of SO3, initially 7‐O,O‐S2 is formed and subsequently its 2‐sulfonic acid, which eventually cyclizes slowly to the 1,3,2,4‐benzodioxadithiin 2,2,4,4‐tetraoxide derivative 12. The 1,3‐isomer 4 with 1 equiv of SO3 yields the 4‐sulfonic acid. With 4 equiv of SO3, initially 4‐O,O‐S2 is formed and subsequently 4‐4, O,O‐S3, which is converted into both 4‐O,O,4,6‐S4 and the cyclization product 10. Eventually, small amounts of 4‐O,2,4,6‐S4 and 14‐2,6‐S2 are formed by transsulfonation.
Observations on the dehydrogenation of α,β‐unsaturated carbonyl compounds with thallium(III) acetate
Authors: Banerjee Ajoy K. , Carrasco María C. , Peña‐Matheud Carmen A.
Published: September 2010

Dehydrogenation of the α,β‐unsaturated ketones 1, 3 and 5 with thallium(III) acetate yielded the dienones 2,4 and 6, respectively. On similar treatment, the ketone 7 afforded the catechol derivative 12, which, on hydrolysis, yielded the tetralone 13.
Acid hydrolysis of polymers and copolymers of N‐vinyl‐N‐methylacetamide
Authors: Buys H. C. W. M. , Vercauteren F. F. , van Elven A. , Tinnemans A. H. A.
Published: September 2010

Acid hydrolysis, under relatively mild conditions (3N HCl, 100°C), of a series of homo‐polymers of N‐vinyl‐N‐methylacetamide, and copolymers thereof with vinyl acetate or methyl acrylate, afforded poly(N‐vinyl‐N‐methylamine), poly(N‐vinyl‐N‐methylamine‐co‐vinyl alcohol) and poly(N‐vinyl‐N‐methylamine‐co‐acrylic acid) in almost quantitative yield. A simple and practical route to poly(N‐vinyl‐N‐methylacetamide‐co‐acrylic acid) and poly(N‐vinyl‐N‐methylacetamide‐co‐vinyl alcohol) has been developed and some kinetic results relating to the hydrolysis step are given. The products were characterized by viscometry, elemental analysis and 13CNMR spectroscopy.
Preparation of 6‐demethoxy‐N‐formyl‐N‐northebaine and its Diels‐Alder reactions with methyl vinyl ketone and nitroethene; novel 8‐nitro‐substituted 6α,14α‐ethenoisomorphinans and 6β,14β‐ethenomorphinans (chemistry of opium alkaloids, part XXVIII)
Authors: Linders J. T. M. , Briel P. , Fog E. , Lie T. S. , Maat L.
Published: September 2010

The synthesis of 6‐demethoxy‐N‐formyl‐N‐northebaine (5) and its Diels‐Alder reactions with methyl vinyl ketone and nitroethene are described.

N‐Demethylation of 6‐demethoxythebaine (3) with diethyl azodicarboxylate, followed by hydrolysis, gave 6‐demethoxy‐N‐northebaine (4) which was N‐formylated with ethyl formate in DMF to give 5, using “Ketjencat LA‐LPV Steamed” as a catalyst.

Reaction of 5 with methyl vinyl ketone using microwave heating gave the expected 7α‐acetyl‐6α,14α‐ethenoisomorphinan 9 by direct crystallization from the reaction mixture. On the other hand, Diels‐Alder reaction of 5 with nitroethene afforded the 7α‐nitro‐6α,14α‐ethenoisomorphinan 12 as a minor product (10%). The major products were 8α‐nitro‐6α,14α‐ethenoisomorphinan (10) (50%) and 8β‐nitro‐6β, 14β‐ethenomorphinan (11) (30%). The structure of the new adducts was elucidated by 1H NMR.

Factors which may influence the course of the Diels‐Alder reaction of morphinan‐6,8‐dienes are discussed. The surprising change in selectivity seems to be governed mainly by steric effects.
The chemistry of D‐gluconic acid derivatives. Part IV Synthesis and reactions of some 2‐deoxy‐D‐hexonic acid derivatives, a new synthesis of 2‐deoxy‐D‐arabino‐hexose and some related compounds
Authors: Regeling Henk , Chittenden Gordon J. F.
Published: September 2010

Treatment of methyl 3,4;5,6‐di‐O‐isopropylidene‐D‐gluconate (7) with triphenylphosphine/carbon‐tetrachloride/imidazole yields the corresponding 2‐chloro‐2‐deoxy‐D‐mannonate 8. The reduction of 8 under a variety of conditions led to a new synthesis of 2‐deoxy‐D‐glucose and some related acyclic compounds. The characterisation, and some reactions of the intermediate products, leading to chirally defined trihydroxy‐2‐alkenoates is also described.
Synthesis of L‐glycero‐α‐D‐manno‐heptopyranose‐containing disaccharide derivatives of the Neisseria meningitidis dephosphorylated inner‐core region
Authors: Boons G. J. P. H. , van derMarel G. A. , van Boom J. H. , Poolman J. T.
Published: September 2010

Hydroxymethylation of correctly protected alkyl α‐D‐manno‐hexodialdo‐1,5‐pyranosides with [(isopropoxydimethylsilyl)methyl]magnesium chloride affords the corresponding silane intermediates, the isopropoxydimethylsilyl group of which can be unmasked with hydrogen peroxide. The L‐glycero‐α‐D‐manno‐heptopyranose (L‐α‐D‐Hepp) derivatives thus obtained can be subsequently used for the preparation of the disaccharides β‐D‐Glcp‐(1‐4)‐L‐α‐D‐Hepp‐OMe and β‐D‐Glcp‐(1‐4)‐L‐α‐D‐Hepp‐O‐(CH2)3NH2.
Chirality in pyridoxal
Authors: van Genderen Marcel H. P. , van Lier Pieter M. , Buck Henk M.
Published: September 2010

Pyridoxal and its iminium derivatives form cyclic compounds via an intramolecular nucleophilic attack. This results in a configurational chirality on C4′ which can be related to out‐of‐plane orientations around the C4C4′ bond in the open forms. 1H‐ and 13C‐NMR structural studies of the cyclic compounds were performed in solution and in the solid state (13C NMR only). It was found that the presence of an additional chiral centre in the iminium moiety gives rise to an excess of one of the diastereomers for the cyclic aminal. This indicates a preference for one of the axially chiral C4‐C4′ conformers prior to ring closure. The present results may be of relevance with respect to the function of the coenzyme pyridoxal phosphate, which forms iminium compounds with l or d amino acids. Axial chirality in these systems has been proposed by us as a mechanism for the stereospecificity of enzymatic amino acid transformations.
Discrimination between polarity and mobility effects on the charge‐transfer fluorescence of Fluoroprobe in organic matrices
Authors: Jenneskens L. W. , van Houwelingen G. D. B. , van Ramesdonk H. J. , Verhey H. J. , Verhoeven J. W.
Published: September 2010

The fluorescence of Fluoroprobe, a molecule with an extremely polar excited state, is studied in matrices consisting of (macro)molecules which contain repeating units of different polarity. In matrices of low molecular weight Fluoroprobe displays its typical bathochromic shift with increasing contribution of polar groups, but an hypsochromic shift is observed in viscous or solid matrices of high molecular weight. This remarkable phenomenon is attributed to loss of mobility, which allows fluorescence of the probe to occur prior to full relaxation of the surrounding matrix sites.
X‐Ray absorption spectroscopic studies on iron in soybean lipoxygenase: A model for mammalian lipoxygenases
Authors: Feiters M. C. , Boelens H. , Veldink G. A. , Vliegenthart J. F. G. , Nolting H.‐F. , Hermes C. , Navaratnam S. , Allen J. C.
Published: September 2010

X‐ray absorption spectroscopy studies are contributing both to the refinement of the geometry of metal sites already known from crystallographic studies and the elucidation of the coordination sphere in metal sites in metalloproteins where only limited information was available. Specific problems in the analysis of coordinating imidazoles can be overcome by applying multiple‐scattering simulations. The model for the lipoxygenase iron site derived from the EXAFS study, a coordination sphere predominated by imidazoles, may require some adjustment in view of the possibility of coordination by water, and has received independent confirmation from studies of amino acid sequence homologies and the interaction with catechols.

The spectroscopy of lipoxygenase is not consistent with the presence of the organic cofactor, PQQ, nor with its coordination to iron, but would be consistent with the presence, but not the coordination to iron, of the carboxy‐hydroxy‐indoloquinone‐glutamic acid cofactor, CHIQG. From the observed amino acid sequence homologies it is concluded that plant lipoxygenases can be good models for the studies of mammalian lipoxygenases.
Interactions between carbonyl‐containing compounds and bismuth trihalides. A spectroscopic investigation
Authors: Delaviz Yadollah , Cabasso Israel , Smid Johannes
Published: September 2010

The high solubility of bismuth tribromide and bismuth trichloride in methyl methacrylate, propylene carbonate and other carbonyl‐containing compounds and polymers results from the interaction between bismuth and the carbonyl moiety. It was established by infrared, 1H‐ and 13C‐NMR measurements that in all these systems a 1:1 complex is formed. The bismuth trihalides are potentially useful as compatible X‐ray contrast additives for carbonyl‐containing polymers.
A comparative study of the liquid‐crystalline behavior of three homologous series of 1,2‐propanediol derivatives
Authors: van Doren Henk A. , van der Geest Ralph , Kellogg Richard M. , Wynberg Hans
Published: September 2010

Homologous series (R = n‐hexyl to n‐tetradecyl) of 3‐(alkylamino)‐, 3‐(alkylthio)‐ and 3‐alkoxy‐1,2‐propanediols have been synthesized and their thermal behavior studied by thermomicroscopy and differential‐scanning calorimetry. The occurrence of liquid‐crystalline behavior was found to be strongly dependent on both the alkyl‐chain length and the hetero‐atom that links the alkyl chain to the 1,2‐propanediol moiety.

No thermotropic liquid‐crystalline behavior could be observed for 3‐alkoxy‐1,2‐propanediols; 3‐(heptylamino)‐ through 3‐(nonylamino)‐1,2‐propanediol exhibit a transient smectic A phase on supercooling of the isotropic liquid, whereas 3‐(hexylthio)‐1,2‐propanediol through 3‐(nonylthio)‐1,2‐propanediol form smectic phases that are quite stable. Although the thermal behavior in the pure form differs considerably, all three classes of compounds are capable of lyotropic mesophase formation in the presence of water.
Synthesis and ligand exchange reactions of (pentamethylcyclopentadienyl)lanthanum aryloxides
Authors: Heeres H. J. , Teuben J. H.
Published: September 2010

Cp*La(OAr)2 (Cp* = η5‐C5Me5)1 is easily accessible by the reaction of La(OAr)3 with Cp*Li. Addition of THF yields the adduct Cp*La(OAr)2(THF)2. Both compounds disproportionate in solution with formation of equilibrium mixtures with comparable amounts of Cp*La(OAr)2, La(OAr)3 and Cp*2LaOAr. The equilibria were studied at various temperatures and thermodynamic parameters were determined from the temperature dependence of the equilibrium constants.
Reversal of an enzymatic decarboxylation: Thiamin mediated carboxylation of acetaldehyde into pyruvic acid
Authors: Foppen Marie‐Anne E. , de Lange Yvonne M. , van Rantwijk Fred , Maat Leendert , Kieboom Antonius P. G.
Published: September 2010

Acetaldehyde has been converted into pyruvic acid (42% yield) via the reaction of 2 ‐(1‐hydroxyethyl)thiamin (3) with carbon dioxide at 50 atm. (DMF, 20 C).
Synthesis of novel morphinan peptides based on ethenoisomorphinans and enkephalin residues containing L‐ and D‐phenylalanine; conformational analysis and preliminary pharmacology (Chemistry of opium alkaloids, Part XXXIII)
Authors: Cappon J. J. , Lie T. S. , Maat L.
Published: September 2010

The morphinan peptidesN‐(4,5α‐epoxy‐3,6‐dihydroxy‐17‐methyl‐6α,14α‐ethenoisomorphinan‐7α‐carbonyl)‐L‐phenylalanine ethyl ester (4),N‐(4,5α‐epoxy‐3,6‐dihydroxy‐17‐methyl‐6α,14α‐ethenoisomorphinan‐7α‐carbonyl)‐D‐phenylalanine ethyl ester (5) andN‐[N‐(4.5α‐epoxy‐3.6‐dihydroxy‐17‐methyl‐6α,14α‐ethenoisomorphinan‐7α‐carbonyl)glycinyl]‐L‐phenylalanine ethyl ester (6) have been prepared from 4,5α‐epoxy‐3,6‐dimethoxy‐17‐methyl‐6α,14α‐ethenoisomorphinan‐7α‐carboxylic acid (7) and the protected amino acids. The morphinan moiety was coupled to the peptide residue via the acid chloride of 7, after which the morphinan peptides wereO‐demethylated with the aid of hydrogen bromide in glacial acetic acid. The dipeptideN‐glycinyl‐L‐phenylalanine ethyl ester was synthesized via the Excess Mixed Anhydride method (EMA). The new morphinan peptides have been characterized by1H and13C NMR spectroscopy. For conformational analysis, the relative stabilities of two possible hydrogen bonds around the C7‐C20 bond have been calculated on a model compound11, using molecular mechanics.
Competitive hemiacetalization and acetalization: Cross‐linking of cellulose by glyoxal
Authors: Sangsari Farid Hamedi , Chastrette Francine , Chastrette Maurice , Blanc Alain , Mattioda Georges
Published: September 2010

The mechanism of cross‐linking of cellulose by glyoxal has been investigated using various alcohols as models for cellulose. Competitive hemiacetalizations of glyoxal show that vicinal diols are much more reactive than isolated alcohols. With a catalyst, both kinds of alcohols react with the hemiacetals, but the isolated alcohols are the most reactive. The main products of acetalization are mixed dioxane bisacetals. Methyl 4‐O‐methyl‐α‐glucoside, considered as a monomeric unit of cellulose, reacts in the same way. The cross‐linking of cellulose by glyoxal is thought to proceed according to the same pattern. The pathways of cross‐linking in the presence of ethylene glycol and diethylene glycol, currently used as co‐reactants of glyoxal, are discussed.
Reductive double alkylation of anthracene with lithium bromoacetate; synthesis of cyclopent[hi]aceanthrylene, a novel dicyclopenta‐fused hydrocarbon
Authors: Boere Ben B. , Mulder Patrick P. J. , Cornelisse Jan , Lugtenburg Johan
Published: September 2010

The synthesis and characterization of cyclopent[hi]aceanthrylene, a novel dicyclopenta‐fused polycyclic hydrocarbon, are described. The key step is the reductive double alkylation of anthracene by lithium bromoacetate in liquid ammonia giving cis‐9,10‐dihydroanthracene‐9,10‐diacetic acid in good yield. Lithium bromoacetate is a better alkylating agent than the sodium iodoacetate formerly used.
Synthesis of a spacer‐containing trimeric fragment of the capsular polysaccharide from Escherichia coli K100
Authors: Elie C. J. J. , Muntendam H. J. , van der Marel G. A. , van Boom J. H. , Hoogerhout P. , van de Werken G.
Published: September 2010

Stereoselective β‐glycosidation of 1,3,4‐tri‐O‐benzyl‐5‐O‐pivaloyl‐D‐ribitol, prepared from L‐ribose, with 1‐O‐acetyl‐2,3,5‐tri‐O‐benzoyl‐β‐D‐ribofuranose gave, after protecting‐group manipulations, the properly protected terminal and non‐terminal units. Elongation (2 ×) of the terminal unit with the incoming non‐terminal unit could be accomplished using the bifunctional phosphorylating reagent, bis(l‐benzotriazolyl) 2‐chlorophenyl phosphate. The trimeric unit thus obtained was condensed, using the same phosphorylating reagent, with the spacer N2‐(benzyloxycarbonyl)‐N1‐(3‐hydroxypropyl)glycinamide, to give, after complete deblocking, the spacer‐containing trimeric unit of Escherichia coli K100.
(S)‐2‐Chloropropanoyl chloride. A convenient reagent for the determination of the enantiomeric composition of α‐substituted α‐hydroxy acids
Authors: Moorlag Henk , Kruizinga Wim H. , Kellogg Richard M.
Published: September 2010

(S)‐2‐Chloropropanoyl chloride reacts cleanly with α‐substituted α‐hydroxy acids (or esters) to give O‐acyl derivatives, which can be used for the establishment of optical purities of the acids or their esters.
“Tert‐amino effect” in heterocyclic synthesis. Synthesis of thieno[3,2‐e]indolizines and thieno[2,3‐c]quinolizines
Authors: Verboom W. , Verboom C. , Eissink I. M. , Lammerink B. H. M. , Reinhoudt D. N.
Published: September 2010

A new and convenient route for the synthesis of the thieno[3,2‐e]indolizines 4a,b,d, the thieno[2,3‐c]quinolizine 4e and their [1]benzothieno analogues 9a,b is presented. Reaction of the (dialkylamino)thiophenes 1, 5 and 7 with (methoxymethylene)malononitrile (2) gives the Michael adducts 3, 6 and 8. Heating of 3 and 8 in refluxing 1‐butanol gives the cyclized products 4 and 9. This cyclization proceeds via a 1,5 hydrogen shift, followed by an intramolecular addition of the carbanion to the iminium double bond in the intermediate 10 formed. The scope and limitations of this approach are discussed.
Structure assignment of some 3,4′‐diquinolinyl sulfides studied by Nuclear Overhauser Effects, X‐ray analysis and reactions with sodium methoxide
Authors: Boryczka Stanislaw , Maślankiewicz Andrzej , Wyszomirski Miroslaw , Borowiak Teresa , Kubicki Maciej
Published: September 2010

1H NMR spectral assignment and nuclear Overhauser enhancement studies of 3‐[[3‐(methylthio)‐4‐quinolinyl]thio]‐4‐methoxyquinoline (2) and ‐4(1H)‐quinolinone (3) were carried out. The structure of compound 2a (R = R′ = Me) was also confirmed by X‐ray analysis. Reactions of compounds of types 2 and 3 with sodium methoxide proceeded with the cleavage of 4‐quinolinyl‐sulfur bond yielding two molecules of 3‐(methylthio)quinolines of type 4 or types 4 and 5.
Towards a rational design of resolving agents. Part III. structural study of two pairs of diastereomeric salts of ephedrine and a cyclic phosphoric acid
Authors: Leusen F. J. J. , Slot H. J. Bruins , Noordik J. H. , van der Haest A. D. , Wynberg H. , Bruggink A.
Published: September 2010

The crystal structures of two pairs of diastereomeric salts consisting of ephedrine and a cyclic phosphoric acid were analyzed in detail. One pair (R = H; Figure 1) shows no difference in solubility, as reflected in identical non‐bonded interaction patterns in the two salts. The other pair (R = CI; Figure 1) shows a significant solubility difference; the crystal packings of these two salts differ considerably. The less soluble salt shows far more favorable Van der Waals interactions, presenting further evidence that the result of optical resolutions by selective crystallization are determined by these weak interactions. This study, in combination with the results presented in the previous paper (Towards a rational design of resolving agents, Part II), suggests that a model might be developed describing a (quantitative) relationship between the lattice energy difference in a diastereomeric pair and the resolution efficiency of the resolving agent.
CO2 hydrogenation into methanol on supported nickel‐molybdenum catalysts
Authors: Ghazi M. , Barrault J. , Menezo J. C.
Published: September 2010

Activity and selectivity in carbon dioxide hydrogenation reactions depend on the nature of the catalyst support. On alumina, methane is the major reaction product whereas on zinc oxide methanol is formed preferably, however with formation of much carbon monoxide.

Kinetic and FTIR measurements show that methanol formation is favored on a ZnO support and reinforce the hypothesis of a direct transformation of carbon dioxide to methanol.
Transimination. Conversion of nitriles into secondary amines in a one‐pot reaction
Authors: Brussee J. , van der Gen A.
Published: September 2010

Transimination has been used as a key step in a convenient, highly erythro selective, one‐pot synthesis of N‐substituted β‐ethanolamines from (R)‐(+)‐[(tert‐butyldimethylsilyl)oxy]‐benzeneacetonitrile (OTBS‐mandelonitrile).
Oxidative methylation of (η5‐C5 Me5)2 TiX (X = Cl, OMe, Me) with group 12 dimethyl complexes to diamagnetic (η5‐C5Me5)2TiX(Me)
Authors: Luinstra Gerrit A. , Teuben Jan H.
Published: September 2010

Tervalent titanium compounds (C5Me5)2TiX (X = OMe, Cl, Me) are selectively oxidized and alkylated at room temperature by ZnMe2 to diamagnetic monomethyl derivatives (C5Me5)2TiX(Me).
Enzymatic optical resolution of norbornanecarboxylic esters using pig liver esterase
Authors: van Gael F. J. C. , Klunder A. J. H. , Zwanenburg B.
Published: September 2010

The hydrolysis of a series of norbornane‐type carboxylic esters catalyzed by pig liver esterase (PLE) has been investigated. It was found that an exo‐eer function (syn to the C7 methylene group) is hydrolyzed with high preference. Enantioselective hydrolysis can be accomplished when a vicinal carbonyl‐containing function (eer, formyl, acetyl) is present in a trans position with respect to the exo eer. The regiospecificity of the enzymatic hydrolysis has been used for the separation of exo/endo mixtures of the cycloadducts derived from cyclopentadiene and alkene esters. The regiospecificity and enantioselectivity of the enzymatic hydrolysis of norbornane‐type esters were analyzed in terms of Tamm's substrate model and also by Griengl's method.
Hydroxynitrile lyases from almond and sorghum as biocatalysts
Authors: Smitskamp‐Wilms E. , Brussee J. , van der Gen A. , van Scharrenburg G. J. M. , Sloothaak J. B.
Published: September 2010

Hydroxynitrile lyases from sweet almond (E.C. 4.1.2.10) and from sorghum bicolor (E.C. 4.1.2.11) have been purified to homogeneity by ion‐exchange chromatography. These enzymes catalyse the decomposition of α‐hydroxynitriles to aldehydes and hydrocyanic acid (HCN) and show great promise for synthetic applications in the reverse reaction: the stereospecific addition of HCN to aldehydes to form enantio‐pure α‐hydroxynitriles.

Physical and kinetic characteristics of the two dominating isoenzymes in each source were compared and revealed appreciable species‐specific differences. The differences in substrate specificity between iso forms within one species, were, however, found to be small.

The native molecular weight for the sorghum lyase was found to be 95 kDa. This is in contrast with an earlier reported value of 180 kDa. From the kinetic parameters Km and Kmax, a specificity constant was calculated, which can be used to predict the potential application of oxynitrilase as a biocatalyst for specific synthetic purposes.
Biosynthesis and chemical determination of polyfluoro‐4‐hydroxyanilines
Authors: Rietjens I. M. C. M. , Koerts J. , Boeren S. , Vervoort J.
Published: September 2010

This paper describes methods for the biosynthesis and chemical determination of polyfluorinated 4‐hydroxyanilines.19F NMR was routinely used to determine recoveries and metabolite patterns.

Male Wistar rats exposed toortho‐ and/ormeta‐polyfluorinated anilines were shown, by19F NMR analysis of urine samples, to excrete a large percentage of the administered dose as the corresponding 4‐aminophenyl sulphate. Using a Bio‐Gel P2 column, this metabolite could be separated from the other metabolites and from (nearly) all urine contaminants. Treatment of the pooled fractions of the Bio‐Gel P2 column with arylsulphatase resulted in hydrolysis of the 4‐aminophenyl sulphate, giving rise to the corresponding polyfluoro‐4‐hydroxyaniline.

The yields of this biosynthetic pathway varied between 10 and 65% depending on the substitution pattern. The yield is mainly determined by the extent to which thein‐vivobiotransformation results in the desired 4‐aminophenyl sulphate and its separation from other urine metabolites on the Bio‐Gel P2 column.

The amounts of polyfluoro‐4‐hydroxyanilines prepared in this way were sufficient to develop a chemical assay for their determination and quantification in biological samples in the μM range. It was demonstrated that polyfluoro‐4‐hydroxyanilines can be measured using the assay described for nonfluorinated 4‐hydroxyaniline.
Optimization of alcohol dehydrogenase activity and NAD(H) regeneration in organic solvents
Authors: Snijder‐Lambers A. M. , Vulfson E. N. , Doddema H. J.
Published: September 2010

Alcohol dehydrogenase (EC 1.1.1.1.) and NAD were co‐immobilized on different supports and used as biocatalysts in organic solvents. Both horse liver alcohol dehydrogenase and yeast alcohol dehydrogenase were tested as biocatalysts for the oxidation of primary alcohols or the reduction of aldehydes. The influence of the kind of support, solvent, water content of the reaction mixture and kind and concentration of the substrates on the redox reaction rate was investigated. NAD(H) was regenerated with the aid of a second substrate. It was shown that both alcohols and aldehydes can serve as reaction media for biocatalysis at molar concentrations, provided the solvents are saturated with water. Highest enzyme activity (2 IU · mg−1 for horse liver alcohol dehydrogenase) was obtained when a hydrophobic long‐chain aldehyde or pentanol was used as the second substrate. Using high concentrations of the second substrate, an equilibrium shift towards over 95 % conversion of substrate was obtained. High total turnover numbers for NAD and NADH of about one million were realized. Thus, coenzyme costs were reduced to about 0.01 US$ per kilogramme of product. This means that the enzyme cos (bout 1000 US$ per kilogramme of product) have become the limiting factor for the application of both alcohol dehydrogenases in production processes for fine chemicals.
Permeability studies on horse liver alcohol dehydrogenase (HLAD) in polyacrylamide gel beads
Authors: Gorrebeeck C. , Lemière G. L. , Dommisse R. A. , Lepoivre J. A. , Alderweireldt F. C. , Spanoghe M. , Lanens D.
Published: September 2010

Polyacrylamide gel beads with monomer concentrations ranging from 5 to 30% and with constant degree of cross‐linking (5%) were prepared. Dried beads were swollen in buffered HLAD/NAD+ solutions and placed in a water‐immiscible organic solution of substrates. Increased enzymatic activity was observed in beads with higher polymer density. Evidence is given that catalyst in the high‐density polymer is concentrated in the outer part of the beads, but is homogeneously distributed in low‐density polymers. This was clearly visualised by high‐resolution NMR imaging on gel beads impregnated with Gd‐DTPA‐labeled HLAD. Furthermore, reaction rates were higher for larger beads.
Enzymatic preparation of acylglycerols of high optical purity
Authors: Ghisalba Oreste , Lattmann René , Gygas Daniel
Published: September 2010

(S)‐3‐O‐acyl‐2‐O‐benzylglycerols with an optical purity of > 98% ee can be prepared in high yield by transesterification in a solvent free system using Pseudomonas fluorescens lipase.
Facile formation of amide bonds between fragments containing unmasked imidazole‐ring systems. Synthesis of N‐[N‐[[[(5‐methyl‐4‐imidazolyl)methyl]thio]acetyl]‐L‐methionyl]histamine
Authors: Modder Johan F. , de Klerk‐Engels Barbara , Ankersmit Hubertus A. , Vrieze Kees , van Koten Gerard
Published: September 2010

The synthesis is reported of the optically pure title compound [α20 −2.31 l·mol−1·dm−1] from a sequence of reactions involving 5‐methyl‐4‐imidazolemethanol, mercaptoacetic acid and (L‐methionyl)histamine. The development of a suitable synthetic route, using N‐benzyl‐2‐[[(5‐methyl‐4‐imidazolyl)methyl]thio]acetamide as a model compound, and the problems associated with the presence of imidazole ring systems in the reagents are discussed. The main problem of the synthesis, i.e., the formation of amide bonds between reagents that contain unmasked imidazole functions, is overcome by using an N,N′‐dicyclohexylcarbodiimide‐activated and N‐hydroxybenzotriazole‐moderated coupling procedure.

The present method seems generally applicable and yields gram quantities in an overall yield of more than 30%, without the need for chromatography techniques.
Synthesis and spectroscopy of chemically modified spheroidenes
Authors: Gebhard R. , van Dijk J. T. M. , van Ouwerkerk E. , Boza M. V. T. J. , Lugtenburg J.
Published: September 2010

The syntheses and spectroscopic properties of the all‐E isomers of 11′,12′‐dihydrospheroidene (2), 3,4,11′,12′‐tetrahydrospheroidene (3), 3,4‐dihydrospheroidene (4), 3,4,5,6‐tetrahydrospheroidene (5), 3,4,7,8‐tetrahydrospheroidene (6) and 15,15′‐didehydrospheroidene (7) are described. Spheroidenes 2‐6 have the same overall shape as native spheroidene (1), which is the carotenoid bound in the photosynthetic reaction centre of Rhodobacter sphaeroides 2.4.1, but they have instead polyene chromophores of nine (4), eight (2, 5) or seven (3, 6) conjugated double bonds. In 7, the central double bond is substituted by a triple bond. The observed λmax values of 2‐6 are generally in good agreement with those calculated via the Fieser‐Kuhn rules. In the mass spectra of 2‐6, fragments due to bis‐allylic fragmentation occur, whereas 1 and 7 do not show this type of fragmentation. A detailed analysis of the 1H‐ and 13C‐NMR spectra of 1‐7 has been achieved by mutual comparison.
Selectivity in reductive elimination from dialkyl(aryl)palladium(IV) complexes, and the observation of benzyl halide transfer from palladium(IV) to palladium(II). The X‐ray structure of methyl(phenyl)(2,2′‐bipyridyl)palladium(II)
Authors: Markies Bertus A. , Janssen Maurits D. , Boersma Jaap , van Koten Gerard , Canty Allan J. , Spek Anthony L.
Published: September 2010

The first arylpalladium(IV) complexes, [PdXMePhR(bpy)] (bpy = 2,2′‐bipyridyl), have been isolated upon oxidative addition of methyl iodide or benzyl bromide to [PdMePh(bpy)]. These dialkyl(aryl)palladium(IV) complexes undergo reductive elimination in solution at ca. 0 °C: [PdBrMePh(CH2Ph)(bpy)] decomposes quantitatively into [PdBr(CH2Ph)(bpy)] and toluene whereas [PdIMe2Ph(bpy)] gives ethane and toluene in 4: 1 ratio together with the corresponding complexes [PdIR(bpy)] (R = Me or Ph). The reaction of methyl iodide with [PdMePh(tmeda)] at 0 °C yields ethane and [PdIPh(tmeda)] without detection of a palladium(IV) intermediate. No reaction of [PdMePh(tmeda)] with benzyl bromide was observed. The first demonstration that organic groups can be transferred from palladium(IV) to palladium(II) is reported. The molecular structure of [PdMePh(bpy)] in the solid state has been determined.
Review of 1H‐ and 13C‐NMR data on homo‐, co‐ and terpolyamides in solution
Authors: van der Velden Geert , Beulen Jo , de Keijzer Henk
Published: September 2010

This paper is a review of ID‐ and 2D‐NMR studies on polyamides in solution. This review includes the effects of the choice of solvent on NMR spectra, possibilities of sequence analysis in co‐ and terpolyamides using either 1H‐ or 13C‐NMR spectroscopy, discrimination between polyamide blends and copolyamides, and observation of cyclic polyamide species in a linear poly‐amide matrix.
A convenient synthesis of aziridine‐2‐carboxylic esters
Authors: Legters Johan , Thijs Lambertus , Zwanenburg Binne
Published: September 2010

Optically active oxirane‐2‐carboxylic esters, prepared from allylic alcohols employing the Sharpless epoxidation, were treated with sodium azide. The azido alcohols obtained were subsequently converted into aziridine‐2‐carboxylic esters by reaction with triphenylphosphine, in good yields and with high optical purity. Various racemic oxirane‐2‐carboxylic esters were subjected to the same sequence of reactions.