Highly diastereoselective, biogenetically patterned synthesis of (+)-(1S,6R)-volvatellin (=(+)-(4R,5S)-5-hydroxy-4-(5-methyl-1-methylenehex-4-en-2-ynyl)cyclohex-1-ene-1-carbaldehyde)

The synthesis of volvatellin (4a), previously isolated from a herbivorous m arine mollusk, was achieved with high diastereoselectivity from putative di etary oxytoxin-1 (2). A biogenetically patterned carbonyl-ene route was cho sen. proceeding from 2 predominantly via the trans cyclization product 3 wi thout the use of enzymes. This challenges the involvement of enzymes in the formation of 4a in nature. The optical purity and absolute configuration ( 1S,4S,6R). assigned to 3 from high-field H-1-NMR examination of its Mosher (MTPA) esters 6. was retained on its chemical conversion to (+)-(1S,6R)-con figured 4a and is consistent with the (4S) configuration previously, establ ished for caulerpenyne (1).