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Stereocontrolled Alkylation of Chiral Pyridinium Salt Toward a Short Enantioselective Access to 2‐Alkyl‐ and 2,6‐Dialkyl‐1,2,5,6‐Tetrahydropyridines
Author(s) -
GuilloteauBertin Bérangère,
Compère Delphine,
Gil Laurent,
Marazano Christian,
Das Bhupesh C.
Publication year - 2000
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/(sici)1099-0690(200004)2000:8<1391::aid-ejoc1391>3.0.co;2-d
Subject(s) - chemistry , pyridinium , enantioselective synthesis , alkylation , reagent , salt (chemistry) , alkyl , dihydropyridine , oxazolidine , carbanion , combinatorial chemistry , organic chemistry , medicinal chemistry , catalysis , calcium
Treatment of salts 1a ‐ b with Grignard reagents gives, after reduction of the resulting unstable dihydropyridines 7 , the tetrahydropyridines 8a ‐ c , with modest selectivities but in very few steps and under practical conditions. Higher stereo‐ and regioselectivities are obtained with salt 1c which gives the tetrahydropyridines 15a ‐ e . In addition, the dihydropyridine intermediates 11b cyclize to give the new oxazolidine derivatives 12a ‐ e , which turn out to be good precursors of the 2,6‐ trans ‐disubstituted tetrahydropyridines 21a ‐ e . Selective syntheses of (−)‐lupetidin, (+)‐solenopsin, and indolizidines (−)‐ 5 and (−)‐ 6 are presented as representative examples of applications.