Total Synthesis of Yuehchukene

Total synthesis of yuehchukene could be realized through the palladium catalyzed carbonylative cross-coupling reaction of indolylborate (2b) with cyclohexadienyl triflate (9) as a key reaction.The bis-indole alkaloid, yuehchukene, whose isolation as a racemic mixture from the root bark of Murraya paniculata (L.) Jack was reported in 1985, 1 consists of hexahydroindeno[2,1-b]indole nucleus.This new class of compound is known to exhibit strong anti-implantation activity and high binding affinity to estradiol receptor, which has been providing several interests in the synthesis of yuehchukene and its analogues, 2 and in the structure-activity relationships, 3 as well.In conjunction with our efforts on the synthetic development of indolylborate, 4 we have devised a reliable synthesis of yuehchukene derivatives based on the palladium catalyzed carbonylative cross-coupling reaction of indolylborate (2a) with cyclohexenyl triflates as a key reaction. 5 This report describes the total synthesis of yuehchukene based on this protocol.