bluuebunny/crossref_metadata_2025 huggingface dataset:
Photo‐oxidation of 4‐aminobiphenyl
Authors: Spee Ton , van Dijk‐Knepper Joke , Cornelisse Jan
Published: September 2010

Upon eosin‐sensitized irradiation (λ > 500 nm) of 4‐aminobiphenyl, 4‐nitrobiphenyl is produced in 50% yield. 3‐Aminobiphenyl is converted into 3‐nitrobiphenyl upon sensitized as well as upon direct irradiation. At sufficiently high concentrations of 4‐aminobiphenyl (≥9 × 10−5 M), the quantum yield of its disappearance becomes greater than unity. Addition of the singlet‐oxygen acceptor, 1,4‐diazabicyclo[2.2.2]octane, surprisingly causes a considerable increase in the quantum yield of the disappearance of 4‐aminobiphenyl. Upon addition of 4‐aminobiphenyl to a solution of the singlet‐oxygen acceptor bilirubin in aqueous 0.2 M NaOH containing eosin, the rate of photobleaching of bilirubin does not decrease, but rather increases sixfold. A possible explanation for these remarkable phenomena is discussed.

There are strong indications that attack of singlet oxygen is the primary step in the photo‐oxidation of 4‐aminobiphenyl.
Synthesis of 10,10‐dimethylprostaglandin F1 and F2 analogues
Authors: Plantema O. G. , de Koning H. , Huisman H. O.
Published: September 2010

The synthesis of the 10,10‐dimethyl analogues of PGF1α (21c), PGF1β (22c), 11‐epi‐PGF1β (23c), PGF2α (30b) methyl ester and their C(15)‐epimers (21d, 22d, 23d and 30c, respectively) is described. Some biological results obtained using these analogues are also discussed.
The composition of methylcopper(I) species in solution. A 1H NMR study
Authors: Westmijze H. , George A. V. E. , Vermeer P.
Published: September 2010

The composition of methylcopper(I) species, prepared from cuprous halides and MeM (M = Li, MgX or Mg1/2) in various ratios, has been studied by means of 1H NMR spectroscopy. Tetrahydrofuran (THF) was used as solvent. Evidence is presented that in the presence of hexamethylphosphoric triamide (HMPT), methylhalocuprates, [MeCuX]M, can be obtained stoichiometrically pure. By means of 1H NMR analysis it could be shown that the complex MeCu[P(OMe)3]3 also exists in solution. The trimethyldicuprate [Me3Cu2]2Mg has only been obtained stoichiometrically pure on starting from MeMgCl and cuprous chloride; it was formed in equilibrium with [Me2Cu]2Mg and [MeCuBr]2Mg when the starting Grignard reagent or the cuprous halide contained bromide. Homocuprates [Me2Cu]M were always obtained in mixtures containing, in addition to the homocuprate, [Me3Cu2]M and MeM when the starting reagent MeM was a Grignard reagent. Attempts to prepare species with another stoichiometry failed when Grignard reagents MeM were used.
Photochemistry of dienones. Part 13. Photochemistry of the valeryl analogues of (E)‐α‐ and (E)‐β‐ionone; absence of Norrish type II processes
Authors: Visser Cornelis P. , van der Wel Hans , Cerfontain Hans
Published: September 2010

The photochemistry of 1b and 2b, i.e. the valeryl analogues of (E)‐α‐ (1a) and (E)‐β‐ionone (2a), respectively, has been studied.

Upon irradiation with λ 254 and 300 nm, the α‐isomer 1b exhibits the same reactions as the parent ionone 1a, viz. (E)‐(Z) isomerization, followed by photo‐deconjugation and subsequent α‐cleavage with formation of the 1,3‐ and 1,5‐acyl shift isomers. Upon irradiation of the β‐isomer 2b with λ 254 nm, only the α‐pyran isomer 15 is formed, although extensive polymerization does occur. Neither the α‐ nor the β‐isomer yields any detectable product resulting from a Norrish type II reaction in which the γ‐hydrogen of the butyl chain is involved.
An approach to the synthesis of 7β‐amino estrogens
Authors: Loozen H. J. J. , van Dam W. , de Winter M. S.
Published: September 2010

The synthesis of 7β‐amino‐1,3,5(10)‐estratriene‐3,17β‐diol (1) has been accomplished using a sequence of transformations proceeding through the 6α,7α‐epoxy‐1,3,5(10)‐estratriene‐3.17β‐diol dibenzyl ether (6). This latter compound is reduced by LiAlH4to give the 7α‐hydroxy compound 7, which, upon subsequent treatment with tosyl chloride (to give8), followed by reaction with NaN3, provided the 7β‐azido‐1,3,5(10)‐estratriene‐3,17β‐diol dibenzyl ether (9). Reduction of9with LiAlH4, followed by catalytic removal of the benzyl ethers, gave1.

Attempts to obtain an epoxide from 1,3,5(10),6‐estratetraene‐2,3–17β‐triol tribenzyl ether (17) failed, and led to the isolation of the corresponding 6α,7α‐diol (19) and 6β,7α‐diol (20). A novel transformation,viz.subsequent treatment of either19or20with SOCl2and LiAlH4, selectively provided 1,3,5(10)‐estratriene‐2,3,7α,17β‐tetraol 2,3,17‐tribenzyl ether (21). Further treatment of21, as delineated for7, provided the required 7β‐amino‐1,3,5(10)‐estratriene‐2,3,17β‐triol (2).
Chemical studies on carbohydrates (III). The ring conversion of hydrazinoaldoses into pseudo‐N‐nucleosides by ring transformation
Authors: Smit P. , Stork G. A. , van der Plas H. C.
Published: September 2010

On reacting 3‐deoxy‐3‐hydrazino‐1,2: 5,6‐di‐O‐isopropylidene‐α‐D‐allofuranose (2) or 3‐deoxy‐3‐hydrazino‐1,2: 5,6‐di‐O‐isopropylidene‐α‐D‐glucofuranose (8) with N‐methylpyrimidinium methyl sulfate (4) at room temperature, formation of 3‐deoxy‐3‐N‐pyrazolyl‐1,2: 5,6‐di‐O‐isopropylidene‐α‐D‐allofuranose (3) and 3‐deoxy‐3‐N‐pyrazolyl‐1,2: 5,6‐di‐O‐isopropylidene‐α‐D‐glucofuranose (9), respectively, takes place. This ring transformation has been explained by an ANRORC mechanism. Similarly, 6‐deoxy‐6‐hydrazino‐1,2‐O‐isopropylidene‐α‐D‐glucofuranose (10) and methyl‐4,6‐O‐benzylidene‐2‐deoxy‐2‐hydrazino‐α‐D‐mannopyranoside (11) react with the pyrimidinium salt to give the corresponding pyrazolylaldoses.

Starting from 3,6‐anhydro‐5‐deoxy‐5‐hydrazino‐1,2‐O‐isopropylidene‐β‐L‐idofuranose (16), in addition to the expected 3,6‐anhydro‐5‐deoxy‐5‐N‐pyrazolyl‐1,2‐O‐isopropylidene‐β‐L‐idofuranose (17a), 3,6‐anhydro‐5‐deoxy‐5‐(1,2,4‐triazol‐1‐yl)‐1,2‐O‐isopropylidene‐β‐L‐idofuranose (17b) is formed. The same conversion of substituted hydrazines into pyrazolyl and triazolyl derivatives is observed in the reaction of 1‐deoxy‐1‐hydrazino‐2,3‐O‐isopopylidene‐D‐ribofuranose (12) with the pyrimidinium salt. This pyrimidine‐to‐triazole ring transformation can also be explained by an ANRORC mechanism.

Further investigation of the reactivity of hydrazinoaldoses towards other positively charged azines shows the general scope of this reaction.
(S‐Butyldithiocarbanilato)copper(I), Cu[BuSC(S)NPh]. Preparation and crystal structure
Authors: Willemse J. , Bosman W. P. , Noordik J. H. , Cras J. A.
Published: September 2010

The preparation and the crystal structure of a copper(I) complex with the deprotoned S‐Butyldithiocarbanilic ester is described. The crystals of Cu[BuSC(S)NPh] are rhombohedral [space group R3, Z = 6, a = 14.684(3) Å, α = 112.96(4)°] with one hexameric unit in the unit cell.
Thermolytic reactions of esters. Part XIII The effect of electron‐attracting α‐substituents in alkyl acetates
Authors: Louw Robert , Tinkelenberg Arie , Werner Erik S. E.
Published: September 2010

α‐Alkylation of esters, e.g. AcO‐iPr → AcO‐tBu, results in a large rate increase for β‐elimination of acetic acid, indicating that in the transition state Cα is positively charged. Replacement of α‐H by electron‐attracting groups Z, such as COOMe, also enhances the rate of formation of alkene. Neither differences in product stability nor steric acceleration appear to play a significant role. A major factor is dipolar destabilization of starting compounds containing two electronegative groups, such as AcOCMe2Z compared with AcO‐tBu. The free energies of the transition states are found to parallel those of the fully ionized species, AcO(‐) + R(+).

At elevated temperatures, esters such as AcOCMe(CN)Ph will give rise to O‐C bond homolysis rather than to molecular elimination of acetic acid.
The electrochemical preparation of [Au9(PPh3)8]+. A comparative study of the structures and properties of [Au9(PPh3)8]+ and [Au9(PPh3)8]3+
Authors: van der Velden J. W. A. , Bour J. J. , Bosman W. P. , Noordik J. H. , Beurskens Paul T.
Published: September 2010

[Au9L8]PF6 (L = PPh3) deposits on the cathode during the coulometric two‐electron reduction of [Au9L8](PF6)3 in acetonitrile at constant potential (−0.60 V relative to an Ag/AgCl electrode). X‐ray crystal structure determination shows a centred cubic arrangement of the 9 Au atoms in the cluster. Physical data, including (solid state) 31P[1H]NMR and 197Au Mössbauer data, are provided and compared with those of [Au9L8]3+.
Studies on polypeptides XL. The role of histidine‐119 in non‐covalent semisynthetic ribonuclease; its replacement by 3‐(3‐pyrazolyl)‐L‐alanine, Nπ‐methyl‐L‐histidine and Nτ‐methyl‐L‐histidine
Authors: Serdijn J. , Bloemhoff W. , Kerling K. E. T. , Havinga E.
Published: September 2010

Non‐covalent semisynthetic ribonuclease analogues are used to study the role of histidine‐119 in the active site of RNase A. The solid‐phase synthesis of three RNase 111‐124 peptides, in which histidine‐119 is replaced by 3‐(3‐pyrazolyl)‐L‐alanine, Nπ‐methyl‐L‐histidine and Nτ‐methyl‐L‐histidine, respectively, is described. The binding of these peptides to RNase 1‐118 protein is examined. The enzymatic activities of the resulting complexes towards first and second step substrates and their binding to the inhibitor 3′‐cytidine monophosphate are determined.

The Nπ‐methylhistidine‐ and the 3‐(3‐pyrazolyl)alanine RNase analogues are devoid of catalytic activity. The Nτ‐methylhistidine analogue is found to be enzymatically active, using yeast ribonucleic acid and 2′,3′‐CMP as substrates. With the latter substrate, kinetic parameters at pH 6.0 have been determined. The results provide strong evidence to suggest that the pros‐nitrogen atom of His‐119 plays an essential role as acid/base catalyst in the enzymatic reaction of RNase. There are indications that the tele‐nitrogen atom of histidine‐119 in the natural enzyme – besides effecting the right pK value at the pros‐nitrogen centre ‐ may also contribute by favouring the optimal steric orientation of the imidazole nucleus and of the pros‐nitrogen in particular.
Modèle mathématique de transfert concerté de proton dans l'hydrolyse d'acétals alkylarylés dérivés du benzaldéhyde
Authors: Lamaty Gérard , Menut Chantal
Published: September 2010

The catalytic constants of six acids (pka ranging from 2. 6 to 8) as well as those of hydroxonium ion and water have been measured in the hydrolysis of six ethyl‐substituted phenylbenzaldehyde acetals.

A good Brønsted correlation is obtained for all compounds, the α coefficient decreasing regularly from 0.7 to 0.5 with the basicity of the leaving group. On the contrary the Hammett plots obtained for each acid are bad, excepted those corresponding to hydronium ion and water.

A model of concerted proton transfer is presented which extends and puts in a mathematical form those previously proposed by Jencks, Kreevoy and Guthrie. With this model we can demonstrate that: (i) the hydrolysis of a given compound can be either a specific‐acid‐or a general‐acid‐catalysed reaction depending upon the strength of the catalyst, (ii) the α Brønsted coefficient is not a measure of the “degree of proton transfer in the transition state” but is rather a measure of the easiness of cleavage of the C‐OAr bond.
Synthesis of fragments of arginine vasopressin and oxytocin containing a cystine residue in position 6
Authors: van Nispen J. W. , Hannink J. A. J. , Schoffelmeer M. S. , Janssen W. P. A. , Polderdijk J. P. , Greven H. M.
Published: September 2010

The synthesis is described of several fragments of the neurohypophyseal nonapeptide hormones arginine vasopressin and oxytocin. One group of fragments is characterized by the presence of an asymmetrical disulfide (a cystine residue in position 6), a second group consists of dimeric (symmetrical disulfides) fragments.

As common intermediates, peptides containing anS‐tritylcysteine residue were synthesized by the fragment condensation approach. Treatment with methoxycarbonylsulfenyl chloride followed by reaction with the free thiol function of cysteine gave the asymmetrical disulfides, while treatment of theS‐tritylcysteine containing peptide with iodine resulted in the corresponding dimers. Peptides with anN‐terminal glutamine residue (position 4) were found to convert spontaneously into the corresponding pyroglutamic acid products.
Effets isotopiques secondaires du deuterium dans l'hydrolyse de l'acétal mixte dérivé du benzaldehyde de l'éthanol et du phénol
Authors: Lamaty Gérard , Menut Chantal , Nguyen Monique
Published: September 2010

The secondary kinetic deuterium isotope effect has been measured for the general acid‐catalysed hydrolysis of benzaldehyde ethyl phenyl acetal (1). It has been found that this α isotope effect increases from 1.06 (H3O+) to 1.26 (H2O), when the strength of the acid catalyst decreases. The significance of this finding is discussed.
Percolation of gases in modified clinoptilolite
Authors: Geussens T. , Verhaert I. , Peeters G. , Vansant E. F.
Published: September 2010

The adsorption properties of partially exchanged (Na,H) clinoptilolites and silanated H‐clinoptilolites have been investigated as a function of the degree of modification.

A different sorption behaviour of N2, Kr and Xe in (Na, H) clinoptilolites is observed in three exchange regions. In samples having a proton loading lower than 10%, adsorption of N2 at 77K, Kr at 195K and Xe at 273K only occurs in the main channels parallel to the c‐axis. Diffusion of Kr into the small channels, which are blocked by the presence of Na+ ions, was observed at 273K. With a proton exchange of 10 to 70%, the small channels become accessible for all gas molecules. In higher exchanged samples (>70%), the maximum adsorption capacity is reached for N2 at 77K and Kr at 195K. The increase of the adsorption capacity with increasing proton content describes a sigmoïdal curve, characteristic of a percolation process.

Structural modification by means of silanation reduces the adsorption of both N2 at 77K and Kr at 273K in a similar way, so that percolation was observed.
Synthesis of 5‐deazaflavine adenine dinucleotide (5‐dFAD) by a modified triester approach
Authors: Smit P. , Stork G. A. , van der Plas H. C. , den Hartog J. A. J. , van der Marel G. A. , van Boom J. H.
Published: September 2010

5‐dFAD was prepared in a reasonable yield by condensing 2′, 3′, 4′‐tri‐0‐tetrahydropyranyl‐5′‐0‐phosphoromorpholino‐5‐deazaflavine with the tri‐n‐octylammonium salt of adenosine‐5′‐phosphate followed by removal of the acid labile tetrahydropyrany1 protective groups.
Synthesis of 3′‐amino‐3′‐deoxyadenosine 5′‐triphosphate
Authors: Visser G. M. , Schattenkerk Cecile , van Boom J. H.
Published: September 2010

Phosphorylation of 2′‐O‐acetyl‐3′‐(trifluoroacetamido)‐3′‐deoxy‐N6‐benzoyladenosine with 1,1′‐[(4‐morpholinyl)phosphorylidenedi‐oxy]bis‐1H‐benzotriazole gives a fully protected intermediate. The latter, after removal of the benzotriazolyl group from the 5′‐phosphotriester function, can be converted by the addition of pyrophosphoric acid, followed by the removal of all protecting groups, intoATP(3′NH2).
Base‐catalysed isomerization of 7‐phenyl‐1,3,5‐cycloheptatriene
Authors: Zwaard A. W. , Prins M. D. , Kloosterziel H.
Published: September 2010

Under the influence of basic alcohol, 7‐phenyl‐1,3,5‐cycloheptatriene (7c) forms its 1‐, 2‐ and 3‐isomers (viz. 1c, 2c and 3c) in parallel reactions, contrary to suggestions made in the literature. The activation parameters for these reactions are given.

The difference in behaviour (in isomerization and exchange reactions under basic conditions) between 7‐(methoxycarbonyl)‐1,3,5‐cycloheptatriene (7b) and 7‐phenyl‐1,3,5‐cyclopentatriene (7c) is explained by the weaker electron‐attracting properties of the phenyl ring as compared to the methoxycarbonyl substituent.
Surface‐modified electrodes (SME)
Authors: Schreurs J. , Barendrecht E.
Published: September 2010

This review deals with the literature (covered up to August 1983), the characterization and the applications of Surface‐Modified Electrodes (SME). As a special class of SME's, the Enzyme‐Modified Electrode (EME) is introduced.

Three types of modification procedures are distinguished; i.e. covalent modification, adsorption modification and polymer‐film modification. A further subdivision is made for catalysts attached to the electrode surface directly or via a bridge molecule. The characterization of SME's is mainly achieved via electrochemical techniques such as cyclic‐ and ac‐voltammetry. This theory is briefly described and illustrated with some of our own results.

The name EME is used for a system in which the enzyme is immobilized at the electrode surface, such that direct electron transfer between electrode and enzyme becomes possible.

The last part of this review deals with the applications of SME's and EME's. Examples are given of some already realized and of some possible applications.
A new approach to the synthesis of 1, 6‐anhydro‐2‐azido‐2‐deoxy‐β‐D‐glucopyranose derivatives
Authors: Kloosterman M. , de Nijs M. P. , van Boom J. H.
Published: September 2010

1, 6‐Anhydro‐β‐D‐mannopyranose was converted in three steps into 1, 6‐anhydro‐3‐0‐(4‐methoxybenzoyl)‐4‐0‐allyl‐β‐D‐mannopyranose in high overall yield. Treatment of the latter with trifluoromethanesulphonic anhydride, followed by direct displacement at 20°c of the triflate ester with lithium azide afforded almost quantitatively 1, 6‐anhydro‐2‐azido‐2‐deoxy‐3‐0‐(4‐methoxybenzoyl)‐4‐0‐allyl‐β‐D‐glucopyranose.
Catalysis of the thermal quadricyclane → norbornadiene isomerisation by mercury(II) halides
Authors: Rood I. D. Ch. , Klumpp G. W.
Published: September 2010

Quadricyclanes are rapidly isomerised to norbornadienes by Hg(II) halides under very mild conditions, corner‐mercuration being assumed to be the essential step. With quadricyclane and 3‐tert‐butyl‐quadricyclane, zero‐order kinetics were found.
Synthesis of the linoleic acid esters of some unsaturated long‐chain ω‐hydroxy fatty acids
Authors: Heslinga L. , Pabon H. J. J.
Published: September 2010

The (Z)‐32‐hydroxy‐23‐Dotriacontenoic acid ester of linoleic acid (19), a compound implicated in skin metabolism, and related compounds have been synthesized in a nine‐steps scheme, starting from 10‐undecynoic acid. Overall yield amounted to 5.2%.
Carbolithiations of 3‐(trimethylsilyl)‐2‐propyn‐1‐ols
Authors: Kruithof K. J. H. , Schmitz R. F. , Klumpp G. W.
Published: September 2010

Alkyllithiums undergo trans addition to 3‐(trimethylsilyl)‐2‐propyn‐1‐ols to yield (1‐lithiovinyl)silanes. Due to unidentified side‐reactions, yields do not exceed 20%
The stereoselective synthesis of 3β‐acetoxy‐2aα,5aβ‐dimethyl‐3,4,5,5a,7,8,8aα,8bα‐octahydro‐2H‐naphtho[1,8‐bc]furan‐2,6(2aH)‐dione, an intermediate in the total synthesis of diterpene mono‐ and di‐lactones
Authors: Reuvers J. T. A. , Wijnberg J. B. P. A. , de Groot Ae.
Published: September 2010

A synthesis of 3β‐acetoxy‐2aα,5aβ‐dimethyl‐3,4,5,5a,7,8,8aα,8bα‐octahydro‐2H‐naphtho‐[1,8‐bc]furan‐2,6(2aH)‐dione 1 is explored starting from 5β‐acetoxy‐1,4aβ‐dimethyl‐4,4a,5,6,7,8‐hexahydronaphthalen‐2(3H)‐one 2 and methyl 5,5‐(ethylenedioxy)‐2‐oxo‐4aβ‐methyl‐2,3,4,4a,5,6,7,8‐octahydronaphthalene‐1‐carboxylate 3. A successful route to lactone 1 was found via methylation and reduction of oxo ester 3 to methyl 5‐oxo‐2β‐acetoxy‐1α,4aβ‐dimethyl‐1,2,3,4,4a,5,6,7,8,8aα‐decahydronaphthalene‐1β‐carboxylate 5. Transformation of 5 into 5‐oxo‐2β‐acetoxy‐6‐bromo‐1α,4aβ‐dimethyl‐1,2,3,4,4a,5,8,8aα‐octahydronaphthalene‐1β‐carboxylic acid 13, followed by lactonization and reduction, gave lactone 1.
The sulfonation and protonation of a series of azulenes. Observation of stable σ‐complexes in the sulfonation of 4,6,8‐trimethylazulene, guaiazulene and bis(3‐guaiazulenyl)methane
Authors: de Wit Peter , Cerfontain Hans
Published: September 2010

The protonation and sulfonation of a series of azulenes (1–9) has been studied. The protonations occur at the 1‐ and 3‐positions, and with6at the formyl oxygen. Reaction of9in CF3CO22H leads to a preferred deuteration of the 3‐ as compared with the 1‐postion (k1/k30.64) which is ascribed to relief of steric strain between the 3‐ and 4‐substituents on deuteration at C(3).

Reaction of the azulenes with SO3in (2H8)dioxane or (2H3)nitromethane leads to sulfodeprotonation at the 1‐ and/or 3‐position and, if these positions are blocked bytert‐butyl groups, to sulfodeprotonation at the less reactive 5‐ and 7‐positions in accordance with predictions based on localization energies. Reaction of2and3in 105.1% H2SO4leads to sulfonation of the respective corresponding 1‐ and 3‐azulenium ions with formation of the 2‐sulfonic acids, whereas reaction of7in 98.4% H2SO4leads to sulfonation of its 1‐azulenium ion at thepara‐position of the 2‐ or 3‐phenyl group.

Reaction of2, 3and9with SO3in (2H3)nitromethane leads to the formation of the stable sulfonation σ‐complexes10 + 11, 14 + 16 + 17and20, respectively. The relatively high stability of the σ‐complexes is due to the high rate of addition of SO3to the azulenes at the 1‐ and 3‐positions, combined with the very low rate of proton transfer of theC(sp3)‐bonded hydrogen of the reaction centre caused by the largeperi‐strain that results on bringing the sulfo group into the plane of the azulene skeleton.

Addition of 1,3‐dimethoxybenzene to the mixtures formed from both2and3with 2 or 3 equivalents of SO3in nitromethane leads to sulfonation of the added substrate. The trans‐sulfonating species derived from2are11and13(of which the latter is the indirect one), and that derived from3is17.
A note on the esterification of α‐D‐glucopyranosyl phosphate with benzyl halides
Authors: Straathof A. J. J. , Kieboom A. P. G. , van Bekkum H.
Published: September 2010

Esterification of the bis(tetrabutylammonium) salt of α‐D‐glucopyranosyl phosphate (1) with benzyl chloride or bromide in acetonitrile gave α‐D‐glucopyranosyl benzyl phosphate (2) in 80‐90% yield. An excess of benzyl chloride catalysed further reaction to a mixture of six phosphoric acid diesters via phosphoric acid triesters and D‐glucopyranosyl chlorides as intermediates. 1‐Bromohexane gave α‐d‐glucopyranosyl hexyl phosphate by the same method.
Suppression of side‐reactions during the attachment of FMOC‐amino acids to hydroxymethyl polymers
Authors: van Nispen J. W. , Polderdijk J. P. , Greven H. M.
Published: September 2010

Two side‐reactions occur during the DCC‐mediated attachment of Fmoc‐amino acids to p‐alkoxybenzyl alcohol resins viz. dipeptide formation and racemization. The addition of 1‐hydroxybenzotriazole in combination with a low reaction temperature is shown to decrease both side‐reactions to an acceptable level without lowering the degree of incorporation.
Substituent effects in carbohydrate chemistry, Part II+. Coupling reactions involving gluco‐ and galacto‐pyranosyl bromides promoted by insoluble silver salts
Authors: van Boeckel C. A. A. , Beetz T.
Published: September 2010

Coupling reactions have been conducted between α‐D‐glyco‐ and galacto‐pyranosyl bromide derivatives and 3‐O‐acetyl‐1,6‐anhydro‐2‐azido‐2‐deoxy‐β‐D‐glucopyranose in the presence of insoluble silver salt promoters. It was found that 4‐O‐acyl functions increase the β/α ratio of the disaccharide formation relative to 4‐O‐alkyl functions, whereas 3‐O‐ and 6‐O‐acyl functions decrease this ratio. It was also found that coupling of α‐D‐galactopyranosyl bromide derivatives gave much higher β/α ratios than did reactions with the corresponding α‐D‐glucopyranosyl bromides.
Substituent effects in carbohydrate chemistry, Part III+. Effects of C‐2 substituents on coupling reactions promoted by insoluble silver salts
Authors: van Boeckel C. A. A. , Beetz T.
Published: September 2010

Coupling reactions have been performed in the 2‐deoxy‐2‐azido‐α‐D‐glucopyranosyl bromide series (i.e. compounds 2, 3, and 4) and with the corresponding 2‐O‐methyl and 2‐O‐(2,2,2‐trifluoro‐ethyl)‐substituted α‐D‐glucopyranosyl bromides (i.e. compounds 1 and 7, respectively) using aglycon 5 in the presence of insoluble silver salt promoters. It was found that coupling of 2‐deoxy‐2‐azido derivatives gave much higher β/α ratios than did the corresponding reactions of the 2‐O‐alkylglucopyranosyl bromides. We assume that through‐bond interactions are responsible for these effects. Other substituent effects are also presented and it is concluded that β‐coupling reactions can be performed in the absence of a participating group at C‐2 if the glycons are appropriately protected. Thus, high β/α ratios may be obtained if acetoxy groups are present at C‐4 and/or 2‐azido‐2‐deoxy functions at C‐2, whereas benzyloxy or allyloxy groups, should be present at C‐3 and C‐6. Furthermore, coupling of galacto‐ and manno‐pyranosyl glycons also gives rise to higher β/α ratios than does coupling of the corresponding glucopyranosyl derivatives.
Synthesis of 1‐(arylthio)alkenyl isocyanides
Authors: van Leusen Albert M. , Wildeman Jurjen , Moskal Janusz , van Hemert Anton W.
Published: September 2010

A series of (Z)‐ and/or (E)‐1‐(arylthio)alkenyl isocyanides (1, 2) was synthesized in good yields from (arylthio)methyl isocyanides (4) and either aldehydes or ketones via a Peterson olefination using silylated 4 as intermediates. Some of the compounds 1 and 2 were also prepared via a Wittig‐Horner approach using diethyl [isocyano(arylthio)methyl]phosphonates (6; not reported previously). Geometrical configurations of the compounds 1 and 2 were determined by 1H NMR in combination with X‐ray analysis.

Compounds 1 and 2 constitute a new type of ketene N,S‐acetals.
Synthesis and conformational analysis of halo[n.3.1]propellanes
Authors: Jenneskens L. W. , Turkenburg L. A. M. , de Wolf W. H. , Bickelhaupt F.
Published: September 2010

A general synthesis of tetra‐, tri‐ and dihalosubstituted propellanes is described starting from 1,2‐dimethylenecycloalkanes 2 to which dichlorocarbene is added to give the expected mono‐addition products 3. Flash vacuum thermolysis of 3 gave the dichlorocyclopentenes 4; addition of dichloro‐ or dibromocarbene to 4 gave the tetrahalo[n.3.1]propellanes 1. The tetrachloropropellane 1c was reduced, with one equivalent of triphenyltin hydride, to give the 9‐exo‐trichloropropellane 5c; a further equivalent of triphenyltin hydride gave the dichloropropellanes 7c and 8c. The endo‐isomer of 5c is 10c, which was obtained by triphenyltin hydride reduction of 4c, followed by dichlorocarbene addition. Finally, triphenyltin hydride reduction of 10c gave the dichloropropellanes 11c and 12c.

A conformational analysis of the chloropropellanes was accomplished by means of MNDO calculations on chlorosubstituted bicyclo[3.1.0]hexanes, as model compounds, and by an investigation of the 1H NMR spectra. In agreement with literature data, it is concluded that the unsubstituted bicyclo‐[3.1.0]hexane subsystem of the propellanes prefers a flat boat conformation of the overall six‐membered ring, but that the (flat) chair is only slightly higher in energy. The situation is reversed if a syn‐chlorine substituent is introduced into the cyclopropane ring, since transannular repulsions force the five‐membered ring down into the overall chair conformation.
2‐(Tert‐butylsulfonyl)‐ethyl 4‐(2,2,6,6‐tetramethylpiperidine‐1‐oxyl) phosphoromorpholidite, a spin‐labeled phosphitylating reagent
Authors: Claesen C. A. A. , Daemen C. J. M. , Tesser G. I.
Published: September 2010

The spin labeled phosphitylating reagent 2‐(tert‐butylsulfonyl)‐ethyl 4‐(2,2,6,6‐tetramethylpiperidine‐1‐oxyl) phosphoromorpholidite (3) rapidly reacts, in the presence of 1‐hydroxybenzotriazole (HOBt), with primary and even secondary hydroxyl functions to give, after oxidation with iodine, a spin labeled phosphotriester, which can be easily deprotected by base to the pertinent spin labeled phosphodiester.
Asymmetric synthesis of α,β‐epoxy sulphonamides (oxiranesulphonamides)
Authors: Nkunya M. H. H. , Zwanenburg B.
Published: September 2010

The asymmetric phase‐transfer‐catalysed (PTC) Darzens condensation of aldehydes and ketones with the chiral reagents (S)‐( ‐ )‐N‐(chloromethylsulphonyl)‐2‐(methoxymethyl)pyrrolidine (2), (S)‐( ‐ )‐tert‐butyl N‐(chloromethylsulphonyl)prolinate (4) and ( + )‐O‐methyl‐N‐(chloromethylsulphonyl)ephedrine (6), using triethylbenzylammonium chloride (TEBA) as the phase‐transfer catalyst, to give optically active diastereomeric α,β‐epoxy sulphonamides (oxiranesulphonamides), is described. Of the three chiral reagents used, 2 was found to be the most effective, imparting an asymmetric induction of up to almost 50%, as assessed by Eu(fod)3‐resolved 1H NMR spectra. The stereochemical course of the asymmetric synthesis is discussed.
The synthesis of glucuronides derived from the antidepressant drugs mianserin and Org 3770
Authors: van Boeckel C. A. A. , Delbressine L. P. C. , Kaspersen F. M.
Published: September 2010

The synthesis of glucuronides derived from mianserin and its 6‐aza analogue (Org 3770) is described. Several methods were investigated. The most successful approach was the coupling of 1,2,3,4,10,14b‐hexahydro‐8‐hydroxy‐2‐(trifluoroacetyl)dibenzo[c,f]pyrazino[1,2‐a]azepine or its 6‐aza analogue with methyl [trichloroethanimidoyl 2,3,4‐tris‐O‐(phenylmethyl)‐α‐D‐glucopyranosid]uronate catalyzed by BF3. Fully protected glycosides were obtained as diastereomeric β/α mixtures. After deprotection the glucuronides of 2‐demethylmianserin and 2‐demethyl‐Org 3770 were synthesized. The correspondingN(2)‐methyl analogues were obtained by reductive methylation. The synthetic β‐glucuronides were identical with the isolated metabolites of mianserin and Org 3770.
Synthesis of the E‐ and Z‐isomers of the potent mutagen (S)‐fecapentaene‐12 by the Horner‐Wittig reaction
Authors: de Wit P. P. , van der Steeg M. , van der Gen A.
Published: September 2010

A synthesis of the E‐ and Z‐isomers of optically pure (S)‐fecapentaene‐12 is described. The method is based on the chromatographic separation of diastereomeric adducts, formed as intermediates in the Horner‐Wittig reaction of an all‐trans undecatetraenal with a chiral phosphine oxide.
Oxydation de sulfure en sulfoxyde par l'hypochlorite de calcium et le chlorite de sodium: Optimisation des conditions opératoires par la méthode des plans d'expériences
Authors: Weber J. V. , Schneider M. , Salami B. , Paquer D.
Published: September 2010

The application of factorial designs and response surface modelling afforded specific conditions for the oxidation sulfide‐sulfoxide using calcium hypochlorite and sodium chlorite. The usefulness of these methods in synthetic chemistry is emphasized.
An alternative synthesis of 17β‐hydroxy‐7α‐methyl‐19‐nor‐17α‐pregn‐5(10)‐en‐20‐yn‐3‐one (Org OD 14)
Authors: van Vliet N. P. , Broess A. I. A. , Peters J. A. M. , van den Broek A. J. , Leemhuis J. A. J. , Zeelen F. J.
Published: September 2010

The title compound (4) was prepared starting from 17β,19‐dihydroxyandrosta‐4,6‐dien‐3‐one 17,19‐diacetate (5). Copper‐catalyzed conjugate addition of methylmagnesium iodide gave, after hydrolysis, 17β,19‐dihydroxy‐7α‐methylandrost‐4‐en‐3‐one (8a), which was converted by oxidation and deacylation into 7α‐methylestr‐5(10)‐ene‐3,17‐dione (11). Selective protection of the 3‐keto group as the dimethyl acetal, followed by ethynylation and deacetalization, gave the desired product 4. The 7β‐methyl adduct, a by‐product in the Grignard reaction, was removed after the oxidation step. Its structure was confirmed by an independent synthesis of the 7β‐methyl‐19‐aldehyde 9b.
Rigid rod polymers with stacked electron donor‐acceptor side‐chains
Authors: van Beijnen A. J. M. , Nolte R. J. M. , Drenth W.
Published: September 2010

The synthesis of polymers of isocyanides having stacks of donor and acceptor functions in their side‐chains is described. These side‐chains are based on the betaine compounds used by Dimroth et al. for the construction of their ET scale of solvent polarity. The UV‐VIS spectra of the polymers together with those of the low‐molecular‐weight model compounds are discussed.
Solvent effects in deamination reactions
Authors: Banert Klaus , Bunse Michael , Engbert Theodor , Gassen Karl‐Rudolf , Kurnianto Apriana W. , Kirmse Wolfgang
Published: September 2010

Nitrous acid deaminations of (S)‐2‐butanamine, (2R,3S)‐3‐methyl‐2‐pentanamine (8), cyclopropananmine (17) and 4,4‐dimethyl‐2‐adamantanamine (30) have been studied in water and in a series of carboxylic acids of decreasing polarity (acetic, 3,3‐dimethylbutyric, 2‐ethylhexanoic acid). The stereochemistry of aqueous deaminations varies from predominant inversion to predominant retention, depending upon the structure of the substrate (steric hindrance, neighbouring‐group participation, etc.). In carboxylic acid media, alcohols arise with predominant retention, i.e. by front‐side attack of the “internal” nucleophile (water). Inverting displacement of nitrogen by the “external” nucleophile (carboxylic acid/carboxylate) increases with decreasing polarity of the solvent. Even cyclopropanamine yields cyclopropyl esters (2‐10%) of inverted configuration, as shown with the aid of deuterium labels. Current mechanistic concepts are modified to account for these results.
Oxidative photoaddition of N‐nitrosodimethylamine to 1‐phenylpropenes
Authors: Chow Yuan L. , Wu Zheng‐Zhi
Published: September 2010

In the presence of hydrochloric acid and under oxygen purging, N‐nitrosodimethylamine photolytically adds to 1‐arylpropenes regiospecifically to give erythro‐ and threo‐α‐amino nitrates as the primary products which can then be reduced, using lithium aluminium hydride, to give α‐amino alcohols or can undergo substitution reactions under photochemical conditions. The stereochemical courses of the addition, as well as the solvolysis of the diastereoisomeric α‐amino nitrates with intramolecular amino group participation, are discussed in order to explain the product distributions.
The gene for ribosomal protein eL12′ from artemia and the genes for ribosomal proteins in yeast share common sequences at their 5′‐ends
Authors: Maassen J. A. , Schop E. N.
Published: September 2010

We have isolated and characterized genomic clones for the ribosomal protein eL12′ from the brine shrimp Artemia. The gene consists of 5 exons spanning a region of more than 11 kilobases on the Artemia genome. DNA sequencing of the region upstream from the transcription initiation point shows the presence of sequence elements that are similar to sequences specific for yeast ribosomal protein genes. This finding suggests a common mechanism for the regulation of ribosomal protein gene expression in eukaryotes.
Di‐n‐alkyl‐(N‐ligand)palladium(II) complexes. Thermolysis and reactions with olefins
Authors: Sustmann Reiner , Lau Jürgen , Zipp Manfred
Published: September 2010

(2,2′‐Bipyridine)diethylpalladium(II) reacts with electron‐deficient olefins (methyl acrylate, acrylonitrile, dimethyl fumarate, dimethyl maleate, maleic anhydride, fumaronitrile and tetracyano‐ethylene) to produce, with the exception of acrylonitrile, almost exclusively n‐butane as the product of reductive elimination. Apart from methyl acrylate and acrylonitrile, organometallic reaction products, (2,2′‐bipyridine)olefinpalladium(0) complexes, are isolated. The temperature dependence of the 1H NMR and 13C NMR spectra of the fumaronitrile complex demonstrates reversible dissociation of the olefin. The thermolysis of the diethylpalladium complexes with 4,4′‐dimethyl‐2,2′‐bipyridine or o‐phenanthroline as ligands leads to no change in behaviour. (2,2′‐Bipyridine)di‐n‐propylpalladium shows, upon thermolysis, the same product distribution as does the diethyl complex, i.e. propane/propene in the absence of olefin and n‐hexane in the presence of tetracyanoethylene.
New functionalized 3,3‐dimethylcyclopropene derivatives and their rearrangement via vinylcarbene intermediates
Authors: Kirms Mark A. , Primke Hartmut , Stohlmeier Michael , de Meijere Armin
Published: September 2010

The 1‐(methylthio)‐substituted cyclopropenes 5a‐c and the corresponding tert‐butyl 1‐cyclopropenecarboxylate 10, which are easily prepared by electrophilic substitution of the protected monolithiated 3,3‐dimethylcyclopropenes 3a‐c, are reasonable stable at room temperature. Upon heating to 150°C, or under photolytic conditions, both 5a and 10 form allenes 8 and 11 exclusively. The first‐order kinetics of the rearrangement 3a→8 was determined as In (k) = 27.54 − 28040/(R.T).
Synthesis of 3‐alkoxy‐7,8‐didehydro‐4‐hydroxy‐N‐methylmorphinan‐6‐ones from morphine. Intermediates for novel A‐ and C‐ring‐functionalized morphinans. (Chemistry of opium alkaloids, Part XXII)
Authors: Brands K. M. J. , Lie T. S. , Maat L.
Published: September 2010

Cesium‐assisted benzylation of morphine (1) gave 3‐O‐benzylmorphine (3) in high yield, leading to a convenient synthesis of 3‐benzyloxy‐7,8‐didehydro‐4‐methoxy‐N‐methylmorphinan‐6‐one (8). This was accomplished by Oppenauer oxidation of 3, followed by 4,5α‐epoxy ring opening and methylation, respectively. The key step in this sequence, viz. the reductive epoxy ring opening with retention of the 7,8‐double bond, could also be applied to codeinone (4) giving quantitatively thebainone‐A (6). The low‐yield synthesis of 3 involving a classical procedure can be explained by the Hofmann degradation products 16 and 17.

The morphinan‐5,7‐diene 14 was obtained from 8 via the p‐toluenesulfonylhydrazone 13. Morphinan‐6,8‐dienes are accessible from 8 using known procedures.
The synthesis and properties of 2,3,23(22),24‐tetrahydro‐21H‐biline‐1,19‐diones, model systems for biliprotein chromophores: 2,3,23(22),24‐tetrahydro‐17,18‐dimethyl‐21H‐biline‐1,19‐dione and its (4E)‐21‐methyl, (4Z + 4E)‐22‐methyl, (9Z + 9E)‐23‐methyl, (4E)‐21,22‐dimethyl and 21,22‐methylene homologues
Authors: Koek J. H. , Hoef K. v. D. , van Es J. J. G. S. , Lugtenburg J. , Fokkens R.
Published: September 2010

The title compounds (1, 2, 5, 6, 7, 13) have been synthesized from the correctly substituted 3,4‐dihydro‐2,2′‐pyrromethen‐5[1H]‐one (14a…e) and 5′‐formyl‐3,4‐dimethyl‐2,2′‐pyrromethen‐5[1H]‐one (15a…d) derivatives via acid‐catalyzed condensation and subsequent neutralization. Using 1H NMR spectroscopy, the configuration of the double bonds of each compound could be established. The systems, locked in only one of the possible tautomeric forms (22‐H or 23‐H), differ in wavelength with regard to the longest absorption maximum from 600 nm for 22N‐alkyl to 550 nm for 23N‐alkyl. The electronic spectra of 1 and 2 indicate that, for the systems liable to undergo 22‐23 proton tautomerization, the equilibrium is largely shifted to the side of the 23‐H form. The stabilization in the 23‐H tautomer is due to the direct interaction of the electron‐rich pyrrolidone ring with the electron‐poor azafulvene ring. The λmax value is only marginally dependent upon the conformation and configuration of the system. The ϵmax values, however, are highly sensitive to the overall conformation, with the helix‐type configuration showing the lower and the more extended systems the higher ϵmax values.

The presence of the 2,3 single bond brings the pKb values into the physiological range, allowing the system to be protonated at pH ≈︁ 7. This means that, in biliproteins, the chromophore may occur in the neutral form or in the positive or negative ion form, each stabilized via the interaction with the peptide chain. At room temperature, the title compounds do not display fluorescence. At liquidnitrogen temperature, however, the model compounds, locked in one tautomer, are good fluorescers. The systems subject to proton tautomerization do not show fluorescence.
Spectroscopy and reactivity of zinc 20‐oxaporphyrin‐IX dimethyl ester
Authors: Hempenius M. A. , Koek J. H. , Lugtenburg J. , Fokkens R.
Published: September 2010

A facile method of preparing zinc 20‐oxaprotoporphyrin‐IX dimethyl ester (1) from biliverdin‐IXα dimethyl ester has been found. According to NMR spectroscopy, the oxa substituent has a pronounced influence on the properties of the macrocyclic ring system. The 1H NMR spectrum reveals an aromatic structure and 13CNMR shows that in 1 a positive charge is delocalized, in agreement with the presence of one positive charge, and further that C‐1 and C‐19 have acquired the highest positive charge. This is corroborated by the reaction with nucleophiles, especially thiolates, leading to isolated adducts which could be well characterized. The adducts are the result of nucleophilic attack on the positions 1 and 19 exclusively, which agrees well with the charge on these positions in 1. The adducts show interesting spectroscopic properties. The study of oxaporphyrins and their nucleophilic adducts may contribute to a fuller understanding of the formation and properties of bile pigments.
Synthesis of fragments of the capsular polysaccharide of Haemophilus influenzae type b: Part I. Preparation of suitably protected 1‐O‐β‐D‐ribofuranosyl‐D‐ribitol building blocks
Authors: Hermans J. P. G. , Poot L. , van der Marel G. A. , Hoogerhout P. , Kloosterman M. , van Boom J. H. , van Boeckel C. A. A. , Evenberg D. , Poolman J. T.
Published: September 2010

The synthesis of the protected ribosylribitol derivatives 15 and 17, which are building blocks for the preparation of fragments of the H. influenzae type b polysaccharide, is presented. Starting from D‐ribonolactone (1), 5‐O‐allyl‐2,3,4‐tri‐O‐benzyl‐D‐ribitol (8) was prepared in seven steps (Scheme 1). Coupling of 8 with 1‐O‐acetyl‐2,3,5‐tri‐O‐benzoyl‐β‐D‐ribofuranose (9) in the presence of trimethylsilyl trifluoromethanesulfonate gave the ribosylribitol derivative 10 (Scheme 2), which was debenzoylated to afford compound 11. The C‐3′‐ and C‐5′‐hydroxyl functions of the ribose moiety of 11 were protected with the 1,1,3,3‐tetraisopropyldisiloxane‐1,3‐diyl group and the C‐2′ position with the benzyloxymethyl group. Compound 13 thus obtained was converted into its 5‐O‐trans‐1‐propenyl isomer 14.

Cleavage of the propenyl group from 14 gave compound 15, which can be phosphorylated at O‐5 of the ribitol. On the other hand, removal of the 3′,5′‐protection from 14 and subsequent blocking of the primary hydroxyl function yielded ribosylribitol derivative 17 having a 3′‐hydroxyl function available for phosphorylation.
A new approach to annelated butenolides. The total synthesis of (±)‐isodrimenin
Authors: Jansen B. J. M. , Peperzak R. M. , de Groot Ae.
Published: September 2010

A new approach to annelated butenolides has been developed starting from trans‐5,5,8a‐trimethyl‐3,4,4a,5,6,7,8,8a‐octahydro‐1(2H)‐naphthalenone (3) and cyclohexanones. A reaction sequence consisting of formylation of the enolates of these ketones, protection of the formyl group as its dioxolane and addition of methoxy(phenylthio)methyllithium has been used to introduce the necessary functionalized carbon atoms. Rearrangement of the adducts to α‐(phenylthio)aldehydes, followed by hydrolysis of the dioxolane, resulted in the formation of butenolides. The method has been demonstrated in the total synthesis of (±)‐isodrimenin. Direct hydrolysis of the adducts, obtained after addition of methoxy(phenylthio)methyllithium, followed by treatment with acid, also gave butenolides.
Phosphorylation of allylic hydroxy groups via phosphite intermediates
Authors: Shadid B. R. , van der Plas H. C. , de Vroom E. , van der Marel G. A. , van Boom J. H.
Published: September 2010

Phosphitylation of an allylic hydroxy group with salicylchlorophosphite gives an allyl 1‐H‐phosphonate mono‐ester, which can be readily oxidized to the corresponding phosphate mono‐ester. Application of this phosphite‐triester approach was further demonstrated in the preparation of 1‐H‐phosphonate and phosphate mono‐esters of N‐protected trans‐zeatin.
Phosphorylation of benzyl‐protected sugar derivatives via 1‐H‐phosphonate intermediates: Synthesis of DL‐myo‐inositol 1,4,5‐tris‐1‐H‐phosphonate
Authors: Dreef C. E. , van der Marel G. A. , van Boom J. H.
Published: September 2010

The crystalline and easily accessible ammonium salt of benzyl‐1‐H‐phosphonic acid has been used for the formation of intermediate benzyl‐1‐H‐phosphonate diester bonds between primary, secondary and anomerically HO‐groups of benzyl‐protected (pseudo)sugar derivatives. These intermediates proved to be very suitable for the preparation of modified and non‐modified phosphate functions.
A note on the use of porous silver silicates as promoter in carbohydrate coupling reactions
Authors: van Boeckel C. A. A. , Beetz T. , Kock‐van Dalen A. C. , van Bekkum H.
Published: September 2010

Different insoluble silver salts were used to promote the β‐glycosidic bond formation between the aglycon methyl (2,3,4‐tri‐O‐benzyl‐α‐D‐glucopyranosyl bromide) uronate (1) and the aglycon 3‐O‐acetyl‐1,6‐anhydro‐2‐azido‐2‐deoxy‐D‐glucopyranose (2). The different promoters have different activity, but do not affect the β/α ratio (β/α = 1.5/1) of this coupling reaction. The most reactive promoter is Ag (I) on silica‐alumina with enhanced cation capacity.
Stereoselective synthesis of cis and trans four‐membered cyclic nitrones
Authors: van Eijk Peter J. S. S. , Overkempe Cor , Trompenaars Willem P. , Reinhoudt David N. , Manninen Lauri M. , van Hummel Gerrit J. , Harkema Sybolt
Published: September 2010

Nitroalkenes 3–5 react with ynamines (1‐aminoacetylenes) 6 to yield four‐membered cyclic nitrones (2,3‐dihydroazete 1‐oxides) 7–13. The nitroalkenes 3 and 5c give the cis fourmembered cyclic nitrones 7–11, whereas 4 and 5b yield the trans four‐membered cyclic nitrones 12–13 upon reaction with 6. Nitroalkene 4i reacts with 6c to give a 1:1 mixture of the cis and trans four‐membered cyclic nitrones 9g and 13i. The trans stereochemistry of trans‐N,N‐diethyl‐2, 3‐dihydro‐3‐(2‐methoxynaphthalenyl)‐2‐methyl‐4‐phenyl‐2‐azetecarboxamide 1‐oxide (13k) was elucidated by means of X‐ray analysis. Only from the reaction of 1‐nitrocyclopentene (5a) with 6c, the initially formed (4 + 2) cycloadduct, the nitronic ester 17 has been isolated. The thermal ring contraction of 17 yields 3a, 4, 5, 6‐tetrahydro‐N,N‐dimethyl‐3‐phenyl‐3H‐cyclopent[c]isoxazole‐3‐ carboxamide (19), the structure of which was established by X‐ray analysis. The trans four‐membered cyclic nitrones are thermally relatively stable compared with the cis nitrones. The mechanism of the stereoselective formation of the nitrones is related to the conformation of the (4 + 2) cycloadduct 16, which could be correlated with Chem‐X and MNDO calculations.
Micellar structure studied by 2D‐NMR
Authors: Nusselder Jan Jaap H. , Engberts Jan B. F. N. , Boelens Rolf , Kaptein Robert
Published: September 2010

This paper describes the possibility of using 2D‐NMR spectroscopy in the study of the morphology of micelles. In aqueous solution, the monomeric surfactant 1‐methyl‐4‐dodecylpyridinium iodide magnified image exhibits positive NOE's whereas negative NOE's are observed for the micellar aggregate. 1‐Methyl‐4‐n‐butylpyridinium iodide magnified image, which does not form micelles, only shows positive NOE's. It is argued that the observation of negative NOE's for micelles is reconcilable with quantitative data for the dynamics of these surfactant aggregates.
An improved synthesis of the antithyroid factor DL‐goitrin
Authors: Brandsma L. , Keegstra M. A. , Verkruijsse H. D. , Bos K. D.
Published: September 2010

DL‐1‐Amino‐3‐buten‐2‐ol HH2CCH‐CH(OH)‐CH2NH2 has been synthesized in a satisfactory overall yield by reduction of the protected cyanohydrin H2CCH‐CH(OR)‐CN [R = ‐CH(CH3)OC2H5] with aluminum hydride, followed by removal of the protecting group with aqueous hydrochloric acid and treatment with potassium hydroxide. The amino alcohol is a key intermediate in a synthesis of the antithyroid factor goitrin reported previously.
Reactions of (μ‐PhPLi)2Fe2(CO)6 with metal halides
Authors: Seyferth Dietmar , Henderson Richard S. , Wood Timothy G.
Published: September 2010

Metal carbonyl cluster complexes containing iron, phenylphosphido units and another metal (Ni, Pd, Pt, Co, Hg) have been prepared by reactions of (μ‐PhPLi)2Fe2(CO)6 with metal halides and (μ‐PhPH)2Fe2(CO)6 with zerovalent metal complexes.