Enantioselective Total Synthesis of (+)-Lysergic Acid, (+)-Lysergol, and (+)-Isolysergol by Palladium-Catalyzed Domino Cyclization of Allenes Bearing Amino and Bromoindolyl Groups
Enantioselective total synthesis of the biologically important indole alkaloids (+)-lysergol, (+)-isolysergol, and (+)-lysergic acid is described. Key features of these total synthesis include (1) a facilesynthesis of a chiral 1,3-amino alcohol via the Pd(0)- and In(I)-mediated reductive coupling reaction between l-serine-derived 2-ethynylaziridine and formaldehyde; (2) the Cr(II)/Ni(0)-mediated Nozaki−Hiyama−Kishi
We have developed a highly regio- and stereoselective synthesis of medium-sized heterocycles containing one or two heteroatoms via cyclization of bromoallenes bearing an oxygen, nitrogen, or carbon nucleophilic functionality in the presence of a palladium(0) catalyst and alcohol. In this reaction, bromoallenes act as an allyl dication equivalent, and the intramolecular nucleophilic attack takes place