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The chemistry of 2 H ‐3,1‐benzoxazine‐2,4(1 H )‐dione (isatoic anhydride). 10 . Reactions with ester enolates. Synthesis of 4‐hydroxy‐1‐methyl‐3‐prenyl‐2(1 H )‐quinolinones, Crucial intermediates in the synthesis of quinoline alkaloids
Author(s) -
Coppola Gary M.
Publication year - 1983
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.5570200515
Subject(s) - chemistry , yield (engineering) , quinoline , lithium (medication) , organic chemistry , medicinal chemistry , medicine , materials science , metallurgy , endocrinology
N ‐Methylisatoic anhydride reacts with the lithium enolates of esters to produce β‐ketoesters 4 in nearly quantitative yield. Thermal cyclization of these relatively unstable intermediates afford the corresponding 3‐substituted‐4‐hydroxy‐1‐methyl‐2(1 H )‐quinolinones ( 5 ) in good yields. The reaction of the lithium enolate of 5‐methyl‐4‐hexenoic acid ethyl ester ( 14 ) with various nuclear substituted isatoic anhydrides gives 4‐hydroxyl‐methyl‐3‐prenyl‐2(1 H )‐quinolinones 8, 9 , and 18 which are highly desirable intermediates in the synthesis of a variety of quinoline alkaloids. Treatment of 18 with DDQ furnishes oricine in 73% yield.