作者:Rolf Huisgen、Xingya Li、Grzegorz Mloston、Rudolf Knorr、Helmut Huber、David S Stephenson
DOI:10.1016/s0040-4020(99)00790-5
日期:1999.10
outside and CO inside conformations. The barrier to enantiomerization (AB → A2 for 5′-H2) is higher (> 20.1 kcal mol−1). Three combinations of rate processes are discussed. Except for the 5′ -methyl compound 19a, the chiral cycloadducts of four other thiocarbonyl ylides to dimethyl azodicarboxylate do not show diastereoisomeric conformations in their NMR spectra at ambient temperature.