Thermal rearrangements of cyclic amine ylides. VIII. Intramolecular cyclization of 2-ethynylpyridine N-ylides into indolizines and cycl (3.2. 2) azines.

H SASHIDA, M KATO, T TSUCHIYA

Index: Sashida, Haruki; Kato, Masanobu; Tsuchiya, Takashi Chemical & Pharmaceutical Bulletin, 1988 , vol. 36, # 10 p. 3826 - 3832

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Citation Number: 9

Abstract

Treatment of 6-unsubstituted 2-ethynyl-1-phenacylpyridinium bromides (10a-c) with 1, 5- diazabicyclo [5.4. 0] undec-5-ene in refluxing benzene resulted in cyclization to give the 3- benzoylindolizines (11) via the N-ylide intermediates 13, whereas heating the salts 10 in refluxing acetic acid afforded the 1-benzoylindolizines (12). Upon similar treatment with the base, 2-ethynyl-6-methylpyridinium salts (20a-c) gave the 3-benzoyl-5-methylindolizines ( ...