Generation and trapping of allene oxides: An approach to chiral, nonracemic α-alkoxyketones
作者:Michael Shipman、Heidi R Thorpe、Ian R Clemens
DOI:10.1016/s0040-4020(98)00878-3
日期:1998.11
Epoxy mesylates 5 react with a variety of sodium alkoxides to produce the corresponding alpha-alkoxyketones in good yields. Evidence is presented for the involvement of transient allene oxides in these reactions. Enantiomerically enriched epoxy mesylates (2R,3S)-5a-c were prepared using the Sharpless asymmetric epoxidation reaction as the key step. These precursors rearrange to alpha-alkoxyketones without significant racemisation under modified reaction conditions (ROK, 18-crown-6, THF, -78 degrees C). The reactions are shown to proceed with stereochemical inversion at the epoxide centre. (C) 1998 Elsevier Science Ltd. All rights reserved.