Steroidal analogues of unnatural configuration. Part I. 4,4,14α-Trimethyl-19(10 → 9β)abeo-10α-pregn-5-enes from cucurbitacins
Abstract
An efficient method for the side-chain cleavage of acetylated cucurbitacins with lead tetra-acetate is described. This reaction afforded 4,4,14α-trimethyl-19(10 → 9β)abeo-10α-pregn-5-ene derivatives of cucurbitacins A, B, C, and E, and further degradation of the cleavage products of cucurbitacins A and B led to A-ring ketones.