A Direct Stereoselective Preparation of a Fish Pheromone and Application of the Zinc Porphyrin Tweezer Chiroptical Protocol in Its Stereochemical Assignment

Abstract

A two-step stereoselective preparation of a goldfish pheromone, 17α,20β-dihydroxy-4-pregnen-3-one, is reported from the readily available cortexolone in 64% overall yield. The (20S)-epimer was also synthesized in three steps from cortexolone with an overall yield of 47%. A microscale chiroptical technique based on a host/guest complexation mechanism between the substrate and a dimeric metalloporphyrin host (tweezer) was used to confirm the stereochemical assignment, while Density Functional Theory (DFT) calculations were employed to explain the high stereoselectivity induced by the 17α-hydroxyl and C18-methyl groups.