A direct and simple activation of quinolines, without isolating unstable intermediates, or using isolated N,O-acetals in the presence of Lewis or Brønsted acids, is described. The procedure is quite straightforward and allows the addition in a stereoselective manner of different aldehydes to various differently substituted quinolines. The desired products were obtained in 28–76 % yields, with dr values up to 83:17 in favor of the syn isomer, and up to 99 % ee. Studies towards the use of acetaldehyde were also performed with different catalysts and the addition was promoted affording the desired product in 62 % yield with 46 % ee. Finally, deprotection and chemical transformations of the enantioenriched adducts were performed.
Mengozzi, L., Gualandi, A., Cozzi, P.G. (2016). Organocatalytic Stereoselective Addition of Aldehydes to Acylquinolinium Ions. EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, 2016(19), 3200-3207 [10.1002/ejoc.201600284].
Organocatalytic Stereoselective Addition of Aldehydes to Acylquinolinium Ions
MENGOZZI, LUCA;GUALANDI, ANDREA;COZZI, PIER GIORGIO
2016
Abstract
A direct and simple activation of quinolines, without isolating unstable intermediates, or using isolated N,O-acetals in the presence of Lewis or Brønsted acids, is described. The procedure is quite straightforward and allows the addition in a stereoselective manner of different aldehydes to various differently substituted quinolines. The desired products were obtained in 28–76 % yields, with dr values up to 83:17 in favor of the syn isomer, and up to 99 % ee. Studies towards the use of acetaldehyde were also performed with different catalysts and the addition was promoted affording the desired product in 62 % yield with 46 % ee. Finally, deprotection and chemical transformations of the enantioenriched adducts were performed.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
