Metal-Templated Macrolactamization of Triamino and Tetramino Esters. Facile Synthesis of Macrocyclic Spermidine and Spermine Alkaloids, (<i>S</i>)-(+)-Dihydroperiphylline, (±)-Buchnerine, (±)-Verbacine, (±)-Verbaskine, and (±)-Verbascenine
The totalsynthesis of spermidine and spermine alkaloids, (S)-(+)-dihydroperiphylline (1), (±)-buchnerine (2), (±)-verbacine (3), (±)-verbaskine (4), and (±)-verbascenine (5), is described. The construction of macrocyclic lactams has been efficiently accomplished by the metal-templated cyclization of triamino esters and tetraamino esters. It was also found that the antimony(III) ethoxide is useful
Synthesis of Polyamine Alkaloids by the Condensation of a Chiral<i>β</i>-Lactam with a Cyclic Imino Ether. (<i>S</i>)-Dihydroperiphylline and Its Derivatives
The synthesis of 13-membered polyamine alkaloid, (S)-dihydroperiphylline, was achieved by the condensation of a chiral β-lactam, (S)-4-phenyl-2-azetidinone, with a cyclic iminoether of a 9-membered lactam, followed by reductive ring expansion. Both of these reactions proceeded with retention of configuration around the chiral center to give the optical pure 13-membered alkaloids.