Isolation and synthesis of the first natural 6-hydroximino 4-en-3-one- steroids from the sponges Cinachyrella spp

Abstract

Two new 6-hydroximino-4-en-3-one steroids: (24R, 6E)-24-ethylcholest-6-hydroximino-4-en-3-one (1) and (6E) cholest-6-hydroximino-4-en-3-one (2), accompanied by the known cholest-4-en-3-one were isolated from a mixture of two morphospecies of the sponge Cinachyrella (C. alloclada and C. apion). Use of spectroscopic methods (NMR and MS) was key to establish their structures which were confirmed by synthesis. Described in this report are the first hydroximino steroids derived from a natural source.