Organic Letters 2010-11-19

Diastereoselective nitrenium ion-mediated cyclofunctionalization: total synthesis of (+)-castanospermine.

Edward G Bowen, Duncan J Wardrop

Index: Org. Lett. 12(22) , 5330-3, (2010)

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Abstract

The asymmetric total synthesis of the α-glucosidase inhibitor (+)-castanospermine is reported. The central theme in our approach to this polyhydroxylated alkaloid is the simultaneous generation of the piperidine ring and the C-1/8a erythro stereodiad through the diastereoselective, oxamidation of an unsaturated O-alkyl hydroxamate. This process is believed to proceed sequentially via singlet acylnitrenium and aziridinium ion intermediates.