Synthesis of P-Chiral Phosphanes from Low-Coordinate Phosphorus Compounds as Bidentate Ligands in Stereoselective Catalysis

手性膦配体在不对称合成和催化中是一类重要的配体。大多数化合物表现出C-手性骨架。P-手性配体远不常见，这主要归因于它们难以合成。2 H-磷杂环戊烯与合适的亲二烯体的不对称磷杂-Diels-桤木反应（利用立体异构面的区分原理）以简单和低成本的方法产生P-手性环状膦。环加成反应的高度非对映选择性过程有助于有效获得立体化学复杂的杂环结构。所得磷杂降冰片烯的裂解和加成反应将用于制备多种基于手性1-磷杂降冰片烷片段的新型磷杂环，2 H-磷杂环戊烯与合适的亚胺进行类似的磷杂-氮杂-Diels-Alder反应，制备对映体纯的1-磷杂-2-氮杂降冰片烯。通过手性试剂（Grignard试剂、醇类、胺类）裂解这些杂环上的活性P-N键，可以合成以2，3-二氢磷杂环戊烯为骨架的手性双齿P，N配体，这些具有1-磷杂环戊烷或2，3-二氢磷杂环戊烯骨架的手性双齿配体可用于催化反应。这些反应包括钯催化的不对称Suzuki-Miyaura偶联反应和不对称烯丙基取代反应、铑催化的烯烃不对称氢化反应、不对称转移氢化反应、使用新型钯钳配合物的不对称oxa-Michael反应和酮的不对称氢化反应。此外，这些催化反应的过渡态的分子建模将进行更好地了解的P-手性配体的影响，对预期的选择性和活性的氢化反应。

Chiral phosphanes are an important class of ligands in asymmetric synthesis and catalysis. Most compounds exhibit a C-chiral backbone. P-chiral ligands are far less common, and this is mainly attributed to their difficult synthetic access. Asymmetric phospha-Diels–Alder reaction of 2H-phospholes with suitable dienophiles (employing the principle of differentiation of stereotopic faces) yields P-chiral cyclic phosphanes in a facile and low-cost procedure. The highly diastereoselective course of the cycloaddition reaction facilitates efficient access to stereochemically complex heterocyclic structures. Cleavage and addition reactions of the resulting phosphanorbornenes will be employed to prepare a diverse range of novel phosphorus heterocycles based on a chiral 1-phosphanornbornane fragment, which are valuable starting materials for the development of novel bidentate P-chiral ligands.An analogous phospha-aza–Diels-Alder reaction of 2H-phospholes with suitable imines will be carried out for the preparation of enantiomerically pure 1-phospha-2-azanorbornenes. Cleavage of the reactive P–N bond of these heterocycles, especially by chiral reagents (Grignard reagents, alcohols, amines), will be employed for the synthesis of chiral bidentate P,N ligands based on a 2,3-dihydrophosphole framework.These readily accessible and easily modifiable chiral, potentially bidentate ligands with 1-phosphanorbornane or 2,3-dihydrophosphole frameworks will be employed in catalytic reactions. These will include palladium-catalysed asymmetric Suzuki-Miyaura coupling and asymmetric allylic substitution reactions, rhodium-catalysed asymmetric hydroformylation of alkenes, asymmetric transferhydrogenation, asymmetric oxa-Michael reactions using novel ruthenium-pincer complexes and asymmetric hydrogenation of ketones. In addition, molecular modelling of the transition states of these catalytic reactions will be performed to get a better understanding of the influence of the P-chiral ligands on the expected selectivities and activities of hydrogenation reactions.