1,6-ADDITION OF ORGANOCOPPER REAGENTS TO 3-ALKYNYL-2-CYCLOALKENONES - REGIOSPECIFIC SYNTHESES OF DIENONES AND ALLENES

被引:25
作者
CHENG, MY [1 ]
HULCE, M [1 ]
机构
[1] UNIV MARYLAND,DEPT CHEM & BIOCHEM,CATONSVILLE,MD 21228
关键词
D O I
10.1021/jo00290a030
中图分类号
O62 [有机化学];
学科分类号
070303 ; 081704 ;
摘要
To investigate the preparation of allenes by means of 1,6-addition reactions to 2-alken-4-ynones, 3-ethynyl-2-cycloalkenones (5) were synthesized and reacted with a variety of organocopper nucleophiles. Such nucleophiles undergo regiospecific 1,6-additions to generate intermediate allenyl enolates (10), which are regiospecifically and stereoselectively protonated to yield a preponderance of (Z)-3-alkenyl-2-cycloalkenones (6–8). The reaction is sensitive to the nature of the organocopper reagent used; higher order cyanocuprates derived from organolithium reagents are the reagents of choice. The intermediate allenyl enolates (10) can be trapped as their enol triflates (13), which in turn can be converted into enallenes (14). Non-organocopper nucleophiles also can add to the terminal carbon of the alkynyl moiety of the enynones studied, but the mechanism may be distinct from that of 1,6-addition: (phenylthio)lithium adds to 3-ethynyl-2-methyl-2-cyclopentenone (5a) by a syn-carbometalation-like mechanism and upon protic quenching yields a preponderance of (E)-2-methyl-3-(2-(phenylthio)ethenyl)-2-cyclopentenone (6h). © 1990, American Chemical Society. All rights reserved.
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页码:964 / 975
页数:12
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