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Improved Synthesis of C 2 ‐Symmetrical Pyridinediols and Synthesis of C s ‐Symmetrical Pyridinediols
Author(s) -
Koning Bartjan,
Buter Jan,
Hulst Ron,
Stroetinga Roelof,
Kellogg Richard M.
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 - 10.1002/1099-0690(200008)2000:15<2735::aid-ejoc2735>3.0.co;2-k
Subject(s) - chemistry , pyridine , regioselectivity , lithium diisopropylamide , diol , stereochemistry , base (topology) , menthone , organic chemistry , deprotonation , catalysis , ion , mathematical analysis , menthol , mathematics
Base‐induced reaction of 2,6‐dimethylpyridine (2,6‐lutidine) ( 1 ) with two equivalents of various ketones has been reported to provide C 2 ‐symmetrical pyridine diols 3 . Closer examination reveals that competitive di‐addition to a single methyl group can occur providing C s ‐symmetrical pyridine diols 7 . By varying the lithiation times, the formation of this side product could be maximized or minimized on the basis of a mechanistic proposal for the competing pathways. The formation of the C s ‐diol 7 could be excluded completely by using potassium diisopropylamide as base; high yields of C 2 ‐symmetrical pyridine diols 3 are obtained. Regioselective additions of 1 to ( R )‐fenchone and (−)‐menthone were also achieved.