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首页> 外文期刊>Chemistry: A European journal >Synthesis of Alkylbismuths by Regiodivergent Carbobismuthination of Simple Alkenes
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Synthesis of Alkylbismuths by Regiodivergent Carbobismuthination of Simple Alkenes

机译：单烯基的区域发散碳原子铋化反应合成烷基铋

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Organobismuth compounds have recently attracted much attention because they show remarkably characteristic reactivities including highly effective initiation of living radical polymerization,[1] para C-H activation of phenol derivatives,[ 2] direct allyl transfer to carbonyls,[1c] a-phenylation of carbonyls,[3] and other traditional reactions such as crosscoupling and addition reactions to carbonyl compounds.[4] However, most of the practical syntheses of organobismuths involve transmetalation between a bismuth halide and an organometallic compound, which has limited the number of compatible functional groups and constricted the development of organobismuth chemistry.[4] Therefore, a new method for the synthesis of organobismuth reagents is highly desirable. Of the options, the carbobismuthination of alkenes represents a powerful tool for the synthesis of alkylbismuth compounds because carbon-carbon and carbon-bismuth bonds can be simultaneously formed to easily give a complex alkylbismuth, but this has never been reported.[5] Recently, our group studied regio- and stereoselective carbometalation by activation of the carbon-carbon multiple bond by a metal halide toward external nucleophilic attack, in which the separate introduction of a carbon nucleophile and a metal into the carbon-carbon unsaturated bond in an anti-addition manner.[6] In this reaction system, carbometalation is caused simply by mixing a metal salt, a carbon nucleophile, and an unsaturated hydrocarbon without the preparation of organometallic nucleophiles in contrast to general carbometalation. Under this concept, we wish to report a novel synthetic method for alkylbismuths by the carbobismuthination of alkenes that directly utilizes bismuth trihalides and ketene silyl acetals. The present carbobismuthination is not only remarkable as a synthetic method of alkylmetals with an ester moiety,[6b, 7] but also has the notable feature whereby a change in the type of halogen on the bismuth atom switches the regioselectivity, which differs from our previously reported version of the carbometalation.[6d] Until now, it has been difficult to realize an efficient switchable regioselectivity in the carbometalation of one alkene, although many highly regioselective reactions have been developed.[ 8] As far as we could ascertain, this is the first example in which the regioselectivity has been switched by the counter anion on a metal in the carbometalation of an alkene (Figure 1).
机译：有机铋化合物近来备受关注，因为它们显示出显着的特征性反应性，包括高效地引发活性自由基聚合反应，[1]苯酚衍生物的对CH活化，[2]直接烯丙基转移至羰基，[1c]羰基的α-苯基化， [3]和其他传统反应，例如羰基化合物的交叉偶联和加成反应。[4]但是，大多数有机铋的实用合成方法都涉及卤化铋和有机金属化合物之间的金属转移，这限制了相容性官能团的数量，并限制了有机铋化学的发展。[4]因此，非常需要一种用于合成有机铋试剂的新方法。在这些选择中，烯烃的碳铋结合是烷基铋化合物合成的有力工具，因为可以同时形成碳-碳和碳-铋键以轻松生成复杂的烷基铋，但这从未被报道。[5]最近，我们的小组研究了通过金属卤化物对外部亲核攻击激活碳-碳多键的区域和立体选择性碳金属化，其中将碳亲核体和金属分别引入到碳-碳不饱和键中加法。[6]在该反应系统中，与一般的碳金属化相反，仅通过混合金属盐，碳亲核试剂和不饱和烃而不产生有机金属亲核试剂就可以引起碳金属化。在此概念下，我们希望报告一种通过直接碳三卤化铋和乙烯酮甲硅烷基乙缩醛通过烯烃的碳羰基化来合成烷基铋的新方法。目前的碳铋共存不仅作为具有酯部分的烷基金属的合成方法[6b，7]十分引人注目，而且具有显着的特征，即铋原子上卤素类型的改变改变了区域选择性，这与我们以前的方法不同[6d]到目前为止，尽管已开发出许多高度区域选择性反应，但在一种烯烃的碳金属化中很难实现有效的可切换区域选择性。[8]据我们所知，这是第一个例子是在烯烃的碳金属化反应中，金属上的抗衡阴离子改变了区域选择性（图1）。

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