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Preparation of 2,6‐bis( l ‐menthopyrzol‐3‐yl)pyridines and their catalytic activity for asymmetric diels alder reaction
Author(s) -
Kashima Choji,
Shibata Saori,
Yokoyama Hiroyo,
Nishio Takehiko
Publication year - 2003
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570400505
Subject(s) - chemistry , cyclopentadiene , enantioselective synthesis , diels–alder reaction , menthone , pyridine , catalysis , ligand (biochemistry) , medicinal chemistry , stereochemistry , aryl , organic chemistry , menthol , receptor , biochemistry , alkyl
3‐Aryl‐ l ‐menthopyrazoles 1 and 2 and related compounds were prepared from l ‐menthone, and their enantioselective activities were discussed as chiral ligands. In this series of compounds, 2,6‐bis(2‐methyl‐ l ‐menthopyrazol‐3‐yl)pyridine ( 8a ), which had both structural features of 3‐phenyl‐ l ‐menthopyrazole ( 1b ) and C 2 symmetric ligand in the molecule, should form the C 2 symmetric complex in situ with Zn(OTf) 2 or Ni(ClO 4 ) 2 •6H 2 O. The subsequent complex catalyzed the Diels Alder reaction of 1‐acryloyl‐3,5‐dimethylpyrazole ( 11a ) with cyclopentadiene ( 12 ) enantioselectively up to 75 % ee.