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

手性膦在不对称合成和催化中是一类重要的配体。大多数化合物都显示出C-手性主链。P-手性配体远不常见，这主要归因于它们难以合成。2H-膦与适当的亲双烯化合物(利用立体面区分原理)进行不对称的膦-Diels-Alder反应，以一种简便和低成本的方法合成了P-手性环膦。环加成反应的高度非对映选择性有助于有效地获得立体化学复杂的杂环结构。基于手性1-膦-冰片的裂解和加成反应将被用来合成一系列新的磷杂环化合物，这是开发新型双齿P-手性配体的有价值的起始原料。2H-膦将与合适的亚胺进行类似的膦-氮杂-Diels-Alder反应以制备对映体纯的1-膦-2-氮杂-冰片。这些杂环的反应性P-N键的断裂，特别是被手性试剂(格氏试剂、醇、胺)切割，将被用于合成基于2，3-二氢磷酸盐框架的手性双齿P，N配体，这些易于获得和易于修饰的手性双齿配体将被用于催化反应。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甲酰化反应、不对称转移氢化反应、使用新型Ru-钳形络合物的不对称Oxa-Michael反应和酮的不对称氢化反应。此外，还将对这些催化反应的过渡态进行分子模拟，以更好地了解P-手性配体对加氢反应预期选择性和活性的影响。

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.