Intramolecular Photochemical Cycloadditions. 3. Perhydrohistrionicotoxin Synthetic Studies: Synthesis of Spirodecanones via Intramolecular Photocycloaddition

Article abstract of DOI:10.1021/jo00179a016

We describe here a full account of our efforts directed toward the synthesis of 4, a known intermediate in the synthsis of perhydrohistrionicotoxin (2).Irradiation of 7 followed by oxidative cleavage of the derived cyclobutene 6 produced 5 or 11, depending on the method of cyclobutene cleavage.While 5 could not be decarboxylated with (Ph3P)3RhCl, thermal decarboxylation of 11 furnished 12a and 12b with the undesired stereochemistry at C(6) predominating, vis a vis perhydrohistrionicotoxin.Thus, while this strategy does not appear to be viable for perhydrohistrionicotoxin, the photocycloaddition cyclobutene cleavage sequence constitutes a valuable method for the rapid construction of the spiro<4.5>decanone ring system with a high degree of stereocontrol.