An organocatalytic cascade approach toward polysubstituted quinolines and chiral 1,4-dihydroquinolines-unanticipated effect of N-protecting groups.
A matter of protection: The outcome of a divergent organocatalytic aza-Michael/aldol cascade process toward quinolines and 1,4-dihydroquinolines depends on the choice of the N-protecting group (see scheme; TEA = triethylamine, TMS = trimethylsilyl). Use of an electron-donating sulfonyl group results in an unanticipated aza-Michael/aldol/aromatization cascade to give polysubstituted quinolines (right). In contrast, chiral 1,4-dihydroquinolines are obtained with an electron-withdrawing sulfonyl group (left).
Department of Chemistry & Chemical Biology, University of New Mexico, MSC03 2060, Albuquerque, NM 87131-0001, USA.
Xinshuai
X
Zhang
Xixi
X
Song
Hao
H
Li
Shilei
S
Zhang
Xiaobei
X
Chen
Xinhong
X
Yu
Wei
W
Wang
D000447:Aldehydes / Q000737:chemistry; D002384:Catalysis; D004583:Electrons; D005021:Ethylamines / Q000737:chemistry; D011804:Quinolines / Q000138:chemical synthesis* / Q000737:chemistry; D014297:Trimethylsilyl Compounds / Q000737:chemistry
C544515:1,4-dihydroquinoline; D000447:Aldehydes; D005021:Ethylamines; D011804:Quinolines; D014297:Trimethylsilyl Compounds; C116609:3-hydroxybutanal; C016162:triethylamine