Highly stereocontrolled alkylation of protected ‘diacetone hexulose aldehydes’
摘要:
Claisen Schmidt aldol condensation (with acetone, catalysed by L- and D-proline), Knoevenagel reaction with acetoacetic acid and the modified Reformatsky reaction with bromoacetone of the 'diacetone hexulose aldehydes' 2 and 7 gave the corresponding beta -hydroxyketones 3 4 and 8-9 as well as the (E)-alpha,beta -enones 5 and 10, respectively. The highest chemo- and stereoselectivities were obtained with the Knoevenagel procedure using L-proline as the catalyst. (C) 2001 Elsevier Science Ltd. All rights reserved.