T. Tsuchiya, Masanobu Kato, H. Sashida
Nov 25, 1984
Citations
1
Influential Citations
11
Citations
Journal
Chemical & Pharmaceutical Bulletin
Abstract
Treatment of 2-ethynyl-1-phenacylpyridinium bromides (1a-c), prepared from 2-ethynylpyridines and phenacyl bromide, with a base, DBU, in refluxing benzene gave 3-benzoylindolizines (2), whereas heating the salts (1) in refluxing acetic acid afforded 1-benzoylindolizines (3). Upon similar treatment with the base, 2-ethynyl-6-methyl-1-phenacyl-pyridinium bromides (10a-c) gave 2-phenylcycl [3. 2. 2] azines (12), together with 3-benzoylindolizines (11). However, the reaction of 6-amino-2-ethynylpyridines (17a-c) with phenacyl bromide resulted in the formation of 1-azaindolizines (18), which were treated with the base to give 1-azacycl [3. 2. 2] azines (19). The mechanisms for these intramolecular cyclization via pyridine N-ylide intermediates are discussed.