General Synthetic Entry to Linearly-Fused Dihydrobenzocyclobutene-1,2-diones and Benzocyclobutene-1,2-diones via Annulation of 1,2-Bis(methylene)carbocycles with 3-Chloro-3-cyclobutene-1,2-dione<sup>1</sup>
作者:Arthur H. Schmidt、Gunnar Kircher、Markus Willems
DOI:10.1021/jo9915877
日期:2000.4.1
The tandem Diels-Alder/dehydrochlorination reaction of semisquaric chloride (1) with the 1,2-bis(methylene)cycloalkanes 2a-c and 1,2-bis(methylene)-4-cyclohexene (9) affords the linearly-fused cycloalkanodihydrobenzocyclobutene-1,2-diones 3a-c and 3,4,7,8-tetrahydrocyclobuta[b]-naphthalene-1,2-dione (10), respectively. On treatment with MnO2, 3a-c are dehydrogenated to the respective carbocycle-fused
半方氯化物(1)与1,2-双(亚甲基)环烷烃2a-c和1,2-双(亚甲基)-4-环己烯(9)的串联Diels-Alder /脱氯化氢反应可得到线性稠合的环烷二氢苯并环丁烯-1,2-二酮3a-c和3,4,7,8-四氢环丁[b]-萘-1,2-二酮(10)。在用MnO 2处理时,以良好的产率将3a-c脱氢为各自的碳环稠合的苯并环丁烯-1,2-二酮4a-c。3a和3b与溴反应得到加成产物5a,b,用三氟乙酸银处理后,得到苯并环丁烯-1,2-二酮4a,b。为了制备目的,序列3-> 5-> 4可以有利地作为“一锅法”进行。4a,b与alpha,alpha'的双缩合反应 -双氰基-邻-二甲苯和邻-苯二胺分别提供了五环联苯撑7a,b和环丁烯撑戊烯8a,b。这些环丁烯二酮表明它们本身是构建具有新颖环序列的延伸的线性稠合多环化合物的基础。通过热分解相应的1,4-二氢-2,3-苯并氧杂i-3-氧化物(阿魏酸)1