Iminophosphorane-based preparation of 2,5-disubstituted oxazole derivatives: Synthesis of the marine alkaloid almazole C

摘要

A four-steps synthesis (32% overall yield) of marine alkaloid almazole C isolated from the red seaweed Haraldiophylum sp. is described. The key step, construction of the central 2,5-disubstituted oxazole ring is based on the aza-Wittig reaction of the iminophosphorane derived from the alpha-azidoacetyl indole and (S)-N-phthaloylphenylalanyl chloride.