ACID-CATALYZED DIMERIZATION OF 10-METHYLENEANTHRONE - SYNTHESIS OF SPIRO-SUBSTITUTED BENZ[DE]ANTHRACENES
ACID-CATALYZED DIMERIZATION OF 10-METHYLENEANTHRONE - SYNTHESIS OF SPIRO-SUBSTITUTED BENZ[DE]ANTHRACENES
复制标题
DOI：
10.1021/jo01325a009
复制
发表时间：
1979-01-01
影响因子：
3.6
通讯作者：
SANCHEZ, D
中科院分区：
文献类型：
--
作者：
BECKER, HD;SANCHEZ, D
发现10-亚甲基蒽酮的酸催化二聚反应生成7 ′-羟基-T，2 ′-二氢螺[蒽-9（10 H），3 ′-[3 H]苯并[de]蒽]-10-酮（9a），其在溶液中与其酮互变异构体9 b处于平衡。因此，以前提出的亚甲基蒽酮二聚体的结构被纠正。对醌甲基化物1通常倾向于与亲核试剂（Nu）进行酸催化反应，通过中间体羟基苄基阳离子2.1~得到1，6-加成产物3：相比之下，据报道，在高温下用酸处理10-亚甲基蒽酮（4）得到据信具有结构5a或5 b的二聚体。4根据最近的一项重新调查，这种二聚体被认为具有螺取代的环丁烷结构6.5然而，没有任何证据支持这种结构。我们有理由怀疑二蒽酮基乙烯结构5 b的正确性，因为我们最近成功地合成了互变异构体7，发现它很容易被分子氧脱氢生成二蒽酮亚基乙烷（8），而不是互变异构为5 b。[6]根据文献[4]重复10-亚甲基蒽酮的酸催化反应，虽然反应缓慢，但确实得到了报道的二聚体产物;然而，其270 MHz NMR光谱与先前提出的三种结构中的任何一种都不相容。因此，我们重新研究了10-亚甲基蒽酮的酸催化反应，发现在三氟乙酸或三氟化硼醚合物存在下，在室温下在氯仿中顺利进行二聚反应。本文介绍了用此法制备的10-亚甲基蒽酮二聚体的结构及其在制备螺取代苯并[德]蒽中的应用。
The acid-catalyzed dimerization of 10-methyleneanthrone is found to give 7'-hydroxy-T, 2'-dihydrospiro [anthracene-9 (10H), 3'-[3//] benz [de] anthracen]-10-one (9a), which in solution is in equilibrium with its keto tautomer 9b. Previously proposedstructures of the methyleneanthrone dimer are thus being corrected. p-Quinone methides 1, in general, are prone to undergo acid-catalyzed reactions with nucleophiles (Nu) to give 1, 6-addition products 3 via intermediate hydroxybenzyl cations 2.1~: i By contrast, treatment of 10-methyleneanthrone (4) with acids at elevated temperature was reported to give a dimer believed to have structure 5a or 5b. 4 According to a very recent reinvestigation, this dimer is suggested to have the spiro-substituted cyclobutane structure 6.5 However, no evidence whatsoever in support of this structure has beenpresented. We had reasons to doubt the correctness of the dianthron-ylethylene structure 5b when we recently succeeded in syn-thesizing the tautomer 7 and found it to be easily dehydro-genated by molecular oxygen to give dianthronylideneethane (8) rather than tautomerizing to 5b. 6 Repeating the acid-catalyzed reaction of 10-methyleneanthrone according to theliterature4 did afford, though rather sluggishly, the reported dimeric product; however, its 270-MHz NMR spectrum turned out to be incompatible with any of the previously proposed three structures. Therefore, we have reinvestigated the acid-catalyzed reaction of 10-methyleneanthrone and found that the dimerization proceeds smoothly at room temperature in chloroform in the presence of trifluoroacetic acid or boron trifluoride etherate. In the present paper we describe the structure of the 10-methyleneanthrone dimer prepared by this method and its utilization in the preparation of spiro-substituted benz [de] anthra-cenes.