467218-16-2Relevant academic research and scientific papers
Total syntheses of the spermine alkaloids (-)-(R,R)-hopromine and (±)-homaline
Ensch, Corinne,Hesse, Manfred
, p. 1659 - 1673 (2007/10/03)
The diastereoselective synthesis of the spermine alkaloid (R,R)-hopromine (2) is described. The as yet unknown absolute configuration of naturally occurring (-)-hopromine (2) is (R,R) and was established by comparison of the reported specific rotation of the natural product with that of the synthetic one. Preparation of the characteristic bis-8-membered lactam scaffold was carried out by convergent build-up of basic chiral azalactam units 21a and 21b and subsequent iterative linking (Schemes 5 and 6). Key steps in the analogous syntheses of 4-alkyl-hexahydro-1,5-diazocin-2(1H)-ones 21a and 21b were the introduction of the unbranched alkyl side chains into their common precursor 14 via cuprate reaction and the Sb(OEt)3-assisted cyclization of the open-chain intermediates 20a and 20b, respectively (Schemes 3 and 4). The chiral iodoester 14 was prepared from commercially available (+)-L-aspartic acid (12). Based on the synthetic strategy developed for (R,R)-hopromine (2), a rapid access to the parent alkaloid homaline (1) in its (±)-form is given.
