Synthesis of Chiral Functionalized Polymers by Alternating Copolymerization of Propene and CO Using the Pd(OAc)2/(S)-P-PHOS Catalyst

Abstract

Pd(OAc) 2 (palladium acetate)/( S )-P-PHOS (( S )-2,2′,6,6′ -tetramethoxy-4,4′ -bis(diphenyl)phosphino)-3,3′ -bipyridine) catalysis systems were applied to the alternating copolymerization of propene and CO in organic solvents to synthesize chiral polyketones. The diastereoselective reduction of a chiral polyketone using excess LiAlH 4 (lithium aluminum hydride) and NaBH 4 (sodium borohydride) as reducing agents gave a new class of optically active polyalcohol and the product yield was more than 90%. In the presence of various amounts of NaBH 4 (NaBH 4 /carbonyl molar ratio of 0.5, 1, and 2), quantitative measurements of the intensity of the carbonyl absorbance at 200–400 nm in the UV (ultraviolet) spectrum showed a reduction of 29%, 71%, and 81%, respectively, for the carbonyl groups. The use of excess BH 3 ·THF (borane tetrahydrofuran complex) as a reducing agent resulted in a partial reduction of the carbonyl groups of the chiral polyketone. The molecular weight of the product was lower than that of the chiral polyketone and the molar optical rotations of the product varied with the reductive conditions. ： 以丙烯和 CO 为原料, Pd(OAc) 2 /( S )-P-PHOS 为手性催化剂, 在有机溶剂中, 经不对称交替共聚反应合成了手性功能高分子聚酮. 当过量的还原剂 LiAlH 4 和 NaBH 4 分别还原聚酮时, 手性聚醇产率达 90%; 当 NaBH 4 /羰基摩尔比分别为 0.5, 1 和 2, 紫外光谱 (200∼400 nm) 检测证明, 手性聚酮中羰基的 29%, 71% 和 81% 分别被还原; 使用过量的还原剂 BH 3 ·THF 时, 手性聚酮中羰基只能部分被还原. 手性聚醇的数均分子量比手性聚酮的低, 产物手性聚醇的摩尔旋光度随还原反应条件而变化. Pd(OAc) 2 /( S )-P-PHOS was used for the copolymerization of propene and CO to give chiral polyketones. The diastereoselective reduction of the product using excess LiAlH 4 and NaBH 4 gave novel chiral polyalcohols.