Preparation of Newly Modified DIOP Bearing Bis(4-dimethylamino-3,5-dimethylphenyl)phosphino Groups and Its Application to Efficient Asymmetric Hydrogenation of Itaconic Acid Derivatives

Abstract

We prepared a modified DlOP analogue bearing bis(4-diniethylatnino-3.5-dimethylphenyI)phospliino groups.Its rhodium conlplex was found to be a useful catalyst for asymn~euic hydrogenation of dimethyl itaconare and itaconic acid derivatives bearing P-aryl groups.previous papers, we described the net role of the elecuonic effects of the phosphino groups on tl 111 our re activities and e~ialitioseiectivities of the rl~odium complex catalysts in die asymmetric ~i~drogenation.~Moreover we developed MOD-DIOP (213 and MOD-BPPM~ bearing bis(4-metlioxy-3.5-~~~~eil~ylphenyl)pl1osphinogroups on the basis of our designing coricept, a i d the 3,5-dime~hyl groups were found to play importatit roles in enllancing the enat~tioselectivities.From lliese findings, we Ihave prepared a newly modified DIOP amlogue ((R.R)-XYL-DIOP, 3) betting bis(4-dit~~ethylamino-3,S-di~11etlylpl1et1yl)pl1oslino groups.Its rhodium complex was found to be more efficient for asynlmeuic hyilrogenntion of dimelliyl itaconate and an itaconic acid derivative bearing a P-11ap11thyl group Illan MOD-DIOP rlidium complex.The latter hydrogeuation product was lecenrly proposed as a key intennediate for the synthesis of new human renin inhibirors.5 XYL-DIOP (3) was prepared in the nianner sllown in Sclterne 1. Bis(4-dimetltylat~tiito-3,5-di1itetltylpl~enyl)-pliospl~itie (4) was prepared by the reduction of the coiresponding pliosplline oxide with LiAIHz-CeCI3 in THF in ~easonteble yield.6 Pl~ospliination of ditosylate (5) with the litl~iated 4 was carried our in THF at -30°C yielding 3.7 Ar=