G. Gribble, M. Saulnier
1993
Citations
0
Influential Citations
43
Citations
Journal
Heterocycles
Abstract
The regioselective ortho-lithiation of 3-chloro (4), 3-fluoro (7), 3-bromo- (10), 2-chloro- (22), and 4-chloropyridine (25) with lithium diisopropylamide affords, after quenching with various electrophiles, the corresponding ortho-disubstituted pyridines in yields from 16-96%. Halogen-metal exchange between 4-iodo-3-chloropyridine (6a) and tert-butyllithium or n-butyllithium provides a convenient generation of 3,4-pyridyne (1), which is trapped in a Diels-Alder reaction with furan and 2,5-dimethylfuran to give 31 and 32 (24-38%)