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The chemistry of 2h‐3,1‐benzoxazine‐2,4(1H)‐dione (isatoic anhydride). 17 Synthesis of 2‐alkyl‐4‐quinolone alkaloids via a one‐step reaction of N‐methylisatoic anhydride with methyl ketone enolates
Author(s) -
Coppola Gary M.
Publication year - 1985
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.5570220256
Subject(s) - chemistry , lithium (medication) , alkyl , olefin fiber , alkaloid , organic chemistry , double bond , medicinal chemistry , catalysis , medicine , endocrinology
Lithium enolates derived from aliphatic methyl ketones react with N ‐methylisatoic anhydride (5) at −78° to give 2‐alkyl‐4‐quinolone alkaloids 7 in a single step. The method was used to synthesize both double bond isomers of 1‐methyl‐2‐(8‐tridecenyl‐4(1 H )‐quinolinone (8) thereby showing that the alkaloid evocarpine possesses the Z‐olefin stereochemistry 8a. Reduction of 8a provided the alkaloid dihydroevocarpine (16). Compound 16 was also directly prepared from the reaction of 5 with the lithium enolate of 2‐pentadecanone.