Practical Synthesis of New Chiral Monophosphine Ligand MOP for Catalytic Asymmetric Reactions

含光活性膦配体的过渡金属配合物催化的不对称反应因其合成用途而引起了人们的极大兴趣。在催化不对称合成的研究中，最令人兴奋和最具挑战性的课题之一是开发手性配体，使其在催化活性和对映选择性上都能有效地适应给定的反应。我们开发了以2-（二苯基膦）-2′-甲氧基-1,1′-联萘基（MeO-MOP）为代表的新型单齿膦配体，其手性源于联萘的轴向手性。轴手性单膦配体MOPs对三种新型钯催化的不对称反应非常有效：1)烯烃的不对称硅氢化反应，为制备旋光性醇提供了一条新的高效途径。2) 1,3-炔的不对称硼氢化反应得到光学活性的烯基硼烷。3)丙烯酯与甲酸的不对称还原。我们从具有光学活性的2,2‘双（羟基）-1,1’-二萘基开始，大规模地阐明了MOP配体的制备方法。利用钯或镍催化的交叉偶联反应，还制备了含有多个2′取代基的新型MOP衍生物。

Asymmetric reactions catalyzed by transition metal complexes containing optically active phosphine ligands have attracted significant interest for their synthetic utility. One of the most exciting and challenging subjects in research on the catalytic asymmetric synthesis is development of the chiral ligand which will fit in with a given reaction efficiently in catalytic activity as well as in enantioselectivity. We have developed new monodentate phosphine ligands represented by 2- (diphenylphosphino) -2'-methoxy-1,1'-binaphthyl (MeO-MOP), whose chirality is due to the binaphthyl axial chirality. The axially chiral monophosphine ligands MOPs were found to be very efficient for three types of new palladium-catalyzed asymmetric reactions : 1) Asymmetric hydrosilylation of olefins which provides a new efficient route to optically active alcohols. 2) Asymmetric hydroboration of 1,3-enynes giving optically active allenylboranes. 3) Asymmetric reduction of allylic esters with formic acid. We have elucidated the preparation methods for MOP ligands in a large scale starting with optically active 2,2'bis (hydroxy) -1,1'-binaphthyl. Preparation of new MOP derivatives bearing several substituents at 2'-position were also achieved by use of palladium-or nickel-catalyzed cross-coupling type reactions.