摘要:
Cyclic N1-alkyl-N2-sulfonyl amidine anions undergo stereoselective aldol reactions to give the syn diastereoisomer as the major product. The ratio of syn to anti aldol products decreases as the size of the N1-alkyl increases. This is interpreted as a change in the transition state from an open-aldol to a closed-Zimmerman-Traxler-type transition state.