Regio- and stereoselective 6- exo - trig radical cyclisations onto chiral perhydro-1,3-benzoxazines: synthesis of enantiopure 3-alkylpiperidines
摘要:
Enantiopure 3-alkyl substituted piperidines are prepared by diastereoselective 6-exo-trig cyclisation of perhydro-1,3-benzoxazines derived from (-)-(8)-amino menthol. The diastereoselective cyclisation is promoted by tributyltin hydride, and the competitive 1,5-hydrogen migration depends on the position of the acceptor double bond and the radical site. (C) 2000 Elsevier Science Ltd. All rights reserved.
Regio- and stereoselective 6- exo - trig radical cyclisations onto chiral perhydro-1,3-benzoxazines: synthesis of enantiopure 3-alkylpiperidines
摘要:
Enantiopure 3-alkyl substituted piperidines are prepared by diastereoselective 6-exo-trig cyclisation of perhydro-1,3-benzoxazines derived from (-)-(8)-amino menthol. The diastereoselective cyclisation is promoted by tributyltin hydride, and the competitive 1,5-hydrogen migration depends on the position of the acceptor double bond and the radical site. (C) 2000 Elsevier Science Ltd. All rights reserved.