Total synthesis of spinosyn A. 1. Enantioselective construction of a key tricyclic Intermediate by a multiple configurational inversion scheme

LA Paquette, Z Gao, Z Ni, GF Smith

Index: Paquette, Leo A.; Gao, Zhongli; Ni, Zhijie; Smith, Graham F. Journal of the American Chemical Society, 1998 , vol. 120, # 11 p. 2543 - 2552

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Citation Number: 64

Abstract

The condensation of (+)-7, 7-dimethoxynorbornen-2-one with the cerium reagent derived from enantiopure bromide (+)-11 gives rise to an exo carbinol, which readily undergoes highly stereocontrolled anionic oxy-Cope rearrangement. Conversion of the resulting ketone into 20 proceeds with clean epimerization at C-11 (spinosyn numbering) to properly set the absolute configuration at that site. Reduction of 20 with lithium in liquid ammonia serves to ...