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首页> 外文期刊>Chemistry: A European journal >Synthesis of a New Chiral Source,(lR,2S)-l-Phenylphospholane-2-carboxylic Acid,via a Key Intermediate alpha-Phenylphospholanyllithium Borane Complex:Configurational Stability and X-ray Crystal Structure of an alphalpha-Monophosphinoalkyllithium Boran
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Synthesis of a New Chiral Source,(lR,2S)-l-Phenylphospholane-2-carboxylic Acid,via a Key Intermediate alpha-Phenylphospholanyllithium Borane Complex:Configurational Stability and X-ray Crystal Structure of an alphalpha-Monophosphinoalkyllithium Boran

机译：通过关键的中间体α-苯基膦酰基硼烷硼烷配合物合成新的手性来源（（R，2S）-1-苯基膦环烷-2-羧酸）：α-α-单膦酰基烷基硼烷硼酸酯的构型稳定性和X射线晶体结构

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摘要

A synthetic route to enantio-merically pure(l,R,2.S)-l-phenylphos-pholane-2-carboxylic acid(1),which is a phosphorus analogue of proline,has been established.A key step is the de-protonation-carboxylation of the 1-phenylphospholane borane complex 3 by using 5BuLi/l,2-dipiperidinoethane(DPE).Configurational stability of the key intermediate,the amine-coordinat-ed alpha-phosphinoalkyllithium borane complex 4,was investigated by employing lithiodestannylation-carboxylation of both diastereomers of the 1-phenyl-2-trimethylstannylphospholane borane complex 7 in the presence of several kinds of amines,and as a result,4 was found to be configurationally labile even at - 100deg C.The key intermediate,the DPE-coordinated tran-l-phenyl-2-phospholanyllithium borane complex 9,was isolated,and the structure was identified by X-ray crystal structure analysis.This is the first X-ray crystal structure determined for an alpha-mono-phosphinoalkyllithium borane complex.Remarkably,the aikyllithium complex is monomeric and tricoordinate at the lithium center with a slightly pyrami-dalized environment,and the existence of a Li-C bond(2.170 A)has been confirmed.Moreover,~1H-~7Li HOESY and ~6Li NMR analyses suggested the structure of 9 in solution as well as the existence of an equilibrium between 9,its cis isomer,and the ion pair 8 at room temperature,which was extremely biased towards 9 at-100deg C.Finally,1 was used as a chiral ligand in a palladium-catalyzed allylic substitution,and the desired product was obtained in high yield with good enantioselectivity.
机译：建立了对映体纯的脯氨酸的磷类似物对映体纯的（1，R，2.S）-1-苯基苯基膦-2-羧酸（1）的合成方法。 5BuLi / l，2-二哌啶基乙烷（DPE）对1-苯基膦烷硼烷配合物3进行质子化-羧化反应。研究了关键中间体中间体-胺配位的α-膦基烷基硼烷硼烷配合物4的构型稳定性。 1-苯基-2-三甲基锡烷基膦烷硼烷配合物7的两种非对映异构体在多种胺存在下的羧基化反应，结果发现即使在100°C时，其构型也是不稳定的。关键中间体DPE分离了配位的反式-1-苯基-2-膦酰基锂硼烷络合物9，并通过X射线晶体结构分析鉴定了结构。这是确定的α-单膦基烷基锂硼烷络合物的第一个X射线晶体结构。值得注意的是，烷基锂复合物是在锂中心的单体和三配位体，具有轻微的吡喃达菲环境，并且已确认存在Li-C键（2.170 A）。此外，〜1H-〜7Li HOESY和〜6Li NMR分析表明溶液中存在9以及室温下9的顺式异构体与离子对8之间存在平衡，在100°C时离子对8极度偏向。最后，1被用作钯中的手性配体催化的烯丙基取代反应，以高收率和良好的对映选择性得到所需产物。

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