Synthetic Studies on Grayanotoxins. Diastereofacially Selective Diels-Alder Reaction of 4-Benzyloxy-2-pentenoate
22 March 2002 (online)
The Diels-Alder reaction of methyl (2Z,4S)-4-(benzyloxy)-2-pentenoate (6) with 1-[(trimethylsilyl)oxy]-1,3-butadiene took place with complete facial selectivity to give the epimeric mixture of the cycloadducts 8 and 9 (2:1). The absolute configuration of 8 and 9 is the mirror image of that of the C-ring of grayanotoxins, the main toxic substances in plant leaves belonging to the family Ericaceae.