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Regioselectivity Control in the Metal-Catalyzed O-C Functionalization of gamma-Allenols, Part 1: Experimental Study

机译:金属催化的γ-烯丙醇的O-C功能化中的区域选择性控制,第1部分:实验研究

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We describe versatile regio-controlled metal-catalyzed heterocyclization reactions of gamma-allenol derivatives leading to a variety of fused enantiopure tetrahydrofurans, dihydropyrans, and tetrahydrooxepines. Regioselectivity control in the O-C functionalization of gamma-allenols can be achieved through the choice of catalyst: use of AuCl3 exclusively affords tetrahydrofurans, use of La[N(SiMe3)(2)](3) usually favors the formation of dihydropyrans, whereas use of PdCl2 solely gives tetrahydrooxepines. In addition, it has been observed that for the Au-catalyzed cycloisomerization, the presence of a methoxymethyl protecting group not only masks a hydroxy functionality, but also exerts directing effects as a controlling unit in a regioselectivity reversal (7-endo versus 5-exo cyclization). In addition, the regioselectivity of the La-catalyzed cycloetherification can be tuned (5-exo versus 7-endo) simply through a subtle variation in the substitution pattern of the allene component (Ph versus Me). Thus, for the first time the regiocontrolled heterocyclization of gamma-allenol derivatives is both catalyst- and substrate-directable. These metal-catalyzed heterocyclization reactions have been developed experimentally (Part 1, this paper), and their mechanisms have additionally been investigated by a theoretical study (Part 2, accompanying paper).
机译:我们描述了通用的区域控制的γ-allenol衍生物的金属控制的金属催化的杂环反应,从而导致各种融合的对映体纯的四氢呋喃,二氢吡喃和四氢氧杂环丁烷。 γ-烯醇的OC功能化中的区域选择性控制可通过选择催化剂来实现:使用AuCl3仅提供四氢呋喃,使用La [N(SiMe3)(2)](3)通常有利于形成二氢吡喃,而使用PdCl2仅产生四氢氧杂环丁烷。另外,已经观察到对于Au催化的环异构化,甲氧基甲基保护基的存在不仅掩盖了羟基官能度,而且在区域选择性逆转中发挥了控制单元的指导作用(7-内基与5-外基)。环化)。另外,可以简单地通过丙二烯组分的取代模式的细微变化(Ph vs Me)来调节La催化的环醚化的区域选择性(5-exo vs. 7-endo)。因此,第一次,γ-烯醇衍生物的区域控制的杂环化是催化剂导向的和底物导向的。这些金属催化的杂环化反应已通过实验开发(本文第1部分),并且通过理论研究(第2部分,随附论文)进一步研究了它们的机理。

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