ISSN:0165-0513    

DOI:10.1002/recl.19861050902

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

ISSN:0165-0513    

DOI:10.1002/recl.19861050903

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractReduction of [20.3.3]propellane‐24,27‐dione afforded only two of the three expected di

ISSN:0165-0513    

DOI:10.1002/recl.19861050904

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

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 byDimrothet al. for the construction of theirETscale of solvent polarity. The UV‐VIS spectra of the polymers together with those of the low‐molecular‐weight model compounds are

ISSN:0165-0513    

DOI:10.1002/recl.19861050905

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractReduction of imines (2a‐e) derived fromn‐butylamine andp‐substituted benzaldehydes, in the presence of magnesium perchlorate, byHantzschester (1), in acetonitrile, proceeds via the corresponding iminium salts formed by protonation of the imines by [Mg(H2O)L5]2+complexes. These complexes are produced by reaction of Mg2+ions with water, which is associated with the solvent acetonitrile. Within the range 1.67 × 10−3‐26.11 × 10−3M of added water, the rate of the reaction shows a direct dependence upon the concentration of water. Rates of reduction of the iminium perchlorates of2a‐eexhibit aHammettrelationship with a ρ

ISSN:0165-0513    

DOI:10.1002/recl.19861050906

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractThe sulfodeprotonation of 1,6:8,13‐propane‐1,3‐diylidene[14]annulene (1) with sulfur trioxide in dioxane and nitromethane at 20°C has been studied. Reaction of1with SO3in (2H8)dioxane yields initially only the 2‐sulfonic acid which is subsequently converted into about equal amounts of the 2,9‐ and 2,12‐disulfonic acid. Upon using 6.0 and 8.0 equiv. of SO3in (2H8)dioxane, the very rapid formation of the 2,9‐ and 2,12‐disulfonic acids is followed by a relatively slow conversion into a mixture of the 2,4,9‐, 2,4,12‐ and 2,5,9‐trisulfonic acids in a ratio ofca.3/3/2. Reaction of1with 8.5 equiv. of SO3in (2H3)nitromethane gave the 2,4,9,11‐, 2,4,9,12‐, 2,4,10,12‐ and 2,5,9,12‐tetrasulfonic acid in yields of 20, 39, 35 and 6%, respectively. The observed sulfonic acid isomer distributions are discussed in terms of the directing effects of the “ideal” [14]annulene and the su

ISSN:0165-0513    

DOI:10.1002/recl.19861050907

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

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 mo

ISSN:0165-0513    

DOI:10.1002/recl.19861050908

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractThe direct irradiation of the charge‐transfer (CT) absorption band of the 1/1 electron donor‐acceptor complexes of dimethoxybenzenes with tetranitromethane leads to aromatic nitration with a high quantum yield. The analogous methoxytoluenes under the same photochemical conditions are converted in equally high yields to products of aromatic trinitromethylation. This dichotomy with different methoxybenzenes (ArH) is discussed within the context of the common reactive intermediates derived from the CT excitation of the complex. The subsequent interactions of the geminate fragments,i.e.,\documentclass{article}\usepackage{amsmath}\pagestyle{empty}\begin{document}$[{\rm ArH}^{\underset{{{\scriptscriptstyle\cdot}}}{+}}, {\rm C}({\rm NO}_2)_3 ^ -,\, {\rm \dot NO}_2] $ \end{document}by radical and ion‐pair annihilation represent a unifying mechanism for the CT photochemistry leading to aromatic nitration and trinitromethyl

ISSN:0165-0513    

DOI:10.1002/recl.19861050909

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractTetranitromethane (TNM) reacts spontaneously withN‐vinylcarbazole to afford the product of 1,2‐addition. Under the same conditions, 9‐vinylanthracene and other olefins do not react with TNM until they are deliberately stimulated by a short pulse of visible light. Photo‐activation under these conditions is associated with the charge‐transfer excitation of the olefin‐TNM complex to produce NO2. The subsequent homolytic addition of NO2to the olefinic donor, followed by electron transfer of the radical adduct, is responsible for the novel chain mechanism for TNM addition in Scheme 1. Homolytic initiation can also be achieved chemically with various additives such as the electron‐rich ferrocene,N,N,N′,N′‐tetramethyl‐1,4‐phenylenediamine, and 5H‐dibenz[b,f]azepine which generate NO2by dissociative electron attachment to TNM. The limited quanta of light and traces of chemical initiators indicate that the chain mechanism for the addition of TNM occurs with relatively long kinetic chain lengths. The mechanistic implications of the chain mechanism for the formation of various types of products is discussed in the con

ISSN:0165-0513    

DOI:10.1002/recl.19861050910

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractThe α‐chloronitroso mannose derivative1undergoes ene reactions with alkenes2to yield nitrone hydrochlorides3which may be hydrolyzed to allylic hydroxylamines. The enophilic reactivity of1is much higher than that of other α‐chloronitroso compounds. The reaction seems to be highly diastereosele

ISSN:0165-0513    

DOI:10.1002/recl.19861050911

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY