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

手性膦是一类重要的不对称合成和催化配体。大多数化合物具有c -手性骨架。p -手性配体远不常见，这主要是由于它们难以合成。不对称磷- diels - alder反应的2h -磷孔与合适的二亲试剂（利用立体面分化的原则）产生p手性环磷化在一个简单和低成本的过程。环加成反应的高度非对映选择性过程有助于有效地获得立体化学复杂的杂环结构。通过裂解和加成反应得到的磷鸟冰片烯将以手性1-磷鸟冰片烯片段为基础制备各种新型磷杂环，为开发新型双齿p手性配体提供有价值的起始材料。将2h -磷酸孔与合适的亚胺进行类似的磷酸-氮杂- diels - alder反应，以制备对映体纯度高的1-磷酸-2-氮杂龙骨烯。这些杂环的反应性P - N键，特别是手性试剂（格氏试剂、醇类、胺类）的裂解，将用于合成基于2,3-二氢膦孔框架的手性双齿P，N配体。这些具有1-磷甲硼烷或2,3-二氢磷酸骨架的手性、潜在双齿配体易于获取和修饰，将用于催化反应。这些将包括钯催化的不对称Suzuki-Miyaura偶联和不对称烯丙基取代反应，铑催化的不对称烯烃氢甲酰化反应，不对称转移氢化反应，使用新型钌螯合物的不对称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的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.