Catalytic Crossed Michael Cycloisomerization of Thioenoates:  Total Synthesis of (±)-Ricciocarpin A

[reaction: see text] Thioenoates are found to participate in highly chemoselective catalytic crossed Michael cycloisomerization with appendant aryl ketone and enoate partners to afford cyclopentene and cyclohexene products. This methodology has enabled a concise total synthesis of the potent molluscicide (+/-)-ricciocarpin A.