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首页> 外文期刊>Chemistry: A European journal >1-Phenyl-1,2-cyclohexadiene: Astoundingly High Enantioselectivities on Generation in a Doering–Moore–Skattebol Reaction and Interception by Activated Olefins
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1-Phenyl-1,2-cyclohexadiene: Astoundingly High Enantioselectivities on Generation in a Doering–Moore–Skattebol Reaction and Interception by Activated Olefins

机译：1-苯基-1,2-环己二烯：在多林-摩尔-Skattebol反应中产生的高对映选择性以及被活化烯烃的拦截

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摘要

The resolution of (1a,5a,6a)- 6-bromo-6-fluoro-1-phenylbicyclo- ACHTUNGTRENUNG[3.1.0]hexane (rac-5) provided the enantiomerically pure precursors ()-5 and (+)-5 of 1-phenyl-1,2-cyclohexadiene. On treatment of ()-5 with methyllithium in the presence of 2,5-dimethylfuran, the pure ()-enantiomer of the [4+2] cycloadduct of 2,5-di- ACHTUNGTRENUNGmethylfuran onto 1-phenyl-1,2-cyclohexadiene was obtained exclusively. From this result, it is concluded that pure (M)-1-phenyl-1,2-cyclohexadiene ((M)-7) emerged from ()-5 and was enantiospecifically intercepted to give the product. In the case of indene as trap for (M)-7, the ()- and the (+)- enantiomer of the [2+2] cycloadduct were formed in the ratio of 95:5. Highly surprising, remarkable enantioselectivities were also observed, when (M)-7 was trapped with styrene to furnish two diastereomeric [2+2] cycloadducts. Hence, the achiral conformation of the diradical conceivable as intermediate cannot play a decisive part. The enantioselective generation of (M)- and (P)-7 by the b-elimination route was tested as well. Accordingly, 1-bromo-2-phenylcyclohexene was exposed to the potassium salt of ()- menthol in the presence of 2,5-dimethylfuran, and the enantiomeric [4+2] cycloadducts of the latter onto (M)- and (P)-7 were produced in the ratio of 55:45.
机译：（1a，5a，6a）-6-溴-6-氟-1-苯基双环-乙酰丙酮[3.1.0]己烷（rac-5）的拆分提供了对映体纯的前体（）-5和（+）-5 1-苯基-1,2-环己二烯。在2,5-二甲基呋喃的存在下，用甲基锂处理（）-5，将2,5-二-乙酰苯并呋喃甲基呋喃的[4 + 2]环加合物的纯（）-对映异构体合成到1-苯基-1,2-上仅获得环己二烯。从该结果可以得出结论，纯的（M）-1-苯基-1,2-环己二烯（（M）-7）从（）-5中出现并被对映体特异性拦截而得到产物。在用茚作为（M）-7的阱的情况下，[2 + 2]环加合物的（）-和（+）-和（+）-对映异构体以95：5的比例形成。当（M）-7用苯乙烯捕获以提供两个非对映异构[2 + 2]环加合物时，也观察到了非常令人惊讶的惊人对映选择性。因此，可以想象为中间体的双自由基的非手性构型不能起决定性的作用。还测试了通过b消除途径对映体选择性生成（M）-和（P）-7。因此，在2,5-二甲基呋喃的存在下，将1-溴-2-苯基环己烯暴露于（）-薄荷醇的钾盐中，并将后者的对映体[4 + 2]环加成物暴露于（M）-和（P ）-7的比例为55:45。

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