The addition of allyltrimethylsilane to cyclic N-acyliminium ions derived from(S)-(+)-mandelic acid and cyclohexyl-based chiral auxiliaries

• Main Authors: D'Oca Marcelo G. M., Pilli Ronaldo A., Pardini Vera L., Curi Denise, Comninos Francisco C. M.
• Format: Article
• Language: English
• Published: Sociedade Brasileira de Química 2001-01-01
• Series: Journal of the Brazilian Chemical Society
• Subjects: (S)-(+)-Mandelic acid; cyclohexyl-based chiral auxiliaries; N-acyliminium ions; pyrrolidine and piperidine derivatives
• Online Access: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50532001000400011

The TiCl4- promoted addition of allyltrimethylsilane to chiral 5- and 6-membered N-acyliminium ions employing (S)-(+)-mandelic acid, (1R,2S)-trans-2-phenyl-1-cyclohexanol and (1R,2S,5R)-8-phenylmenthol derivatives as chiral auxiliaries occurred with low to moderate diastereoisomeric ratios (1:1-6:1) to afford 2-substituted amides and carbamates in good yields. The best diastereoselection was observed with (1R,2S,5R)-8-phenylmenthol as the chiral auxiliary. The 2-substituted amides and carbamates were converted to the corresponding alkaloids (S)- and (R)-propyl pyrrolidine and coniine with efficient recovery of the chiral auxiliaries.