bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modèle mathématique de transfert concerté de proton dans l'hydrolyse d'acétals alkylarylés dérivés du benzaldéhyde
Authors: Lamaty Gérard , Menut Chantal 
Published: September 2010

AbstractThe 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

AbstractThe 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

AbstractThe 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

AbstractThe 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

Abstract5‐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

AbstractPhosphorylation 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

AbstractUnder 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

AbstractThis 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

Abstract1, 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

AbstractQuadricyclanes 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

AbstractThe (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

AbstractAlkyllithiums 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

AbstractA 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

AbstractThe 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

AbstractEsterification 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

AbstractTwo 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

AbstractCoupling 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

AbstractCoupling 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

AbstractA 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

AbstractA 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

AbstractThe 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

AbstractThe 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

AbstractThe 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

AbstractA 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

AbstractThe 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

AbstractThe 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

AbstractThe 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

AbstractNitrous 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

AbstractIn 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.