
%0 Journal Article
%A Mander, LN 
%A Turner, JV 
%T Studies on intramolecular alkylation. XII. Stereochemical aspects of the preparation of &#946;,&#947;-unsaturated aldehydes from the [2,3]-sigmatropic rearrangement of ammonium ylides
%J Australian Journal of Chemistry
%D 1980/07/01
%V 33
%N 7
%P 1559-1568
%K 
%R https://doi.org/10.1071/CH9801559
%U https://www.publish.csiro.au/paper/CH9801559 
%X The [2,3]-sigmatropic rearrangement of a series of acetonitrile-derived allylic ammonium ylides [RCH2N+ (C4H8)-CHCN; R = 4'-t- butylcyclohexylidenemethyl (3), 4'-t-butylcyclohex-1-enyl (10), 5'-t- butyl-2'-methylcyclohex-1-enyl (14), 4'-t-butyl-2'-methylcyclohex-1- enyl (20)], followed by acid-catalysed hydrolysis in each case, furnished an excellent yield of a diastereomeric pair of &#946;,&#947;-olefinic aldehydes [(5)/(6), (12)/(13), (15)/(16) and (21)/(22)]. With cyclohexylidene ylide (4) addition of the carbanion to the more exposed (equatorial vector) face is strongly preferred. In the cyclohexenyl examples there is a clear stereoelectronic requirement in opposition to steric forces which leads mainly to axial carbon-carbon bond formation. 
