The Michael-aldol product (8) from PhSH-PhCHO-2 (5H)-furanone is converted by acids to the tricyclic compound (9), without the intermediacy of the olefin (10). The podophyllotoxin analog (22) was similarly obtained. The all-trans compounds were isomerised by DBU to the cis lactones. Hydroxylated analogs (26) and (33) were produced by reacting 2-(5H)- furanone with appropriate 2-mercaptobenzophenones. Thermal rearrangement of the ...