聚[(S)-3-乙烯基-2,2'-二羟基-1,1'-联萘]的钛配合物催化三乙基铝对醛的不对称加成反应

Asymmetric Addition of Triethylaluminium to Aldehydes Catalyzed by Titanium-Poly[( S)-3-vinyl-2,2'-dihydroxyl-1,1'-binaphthyl] Complexes

通过维蒂希反应合成了(S)-3-乙烯基-2,2'-甲氧甲氧基-1,1'-联萘.将单体(S)-3-乙烯基-2,2'-甲氧甲氧基-1,1'-联萘用偶氮二异丁腈作引发剂进行自由基聚合得到了聚[(S)-3-乙烯基-2,2'-二甲氧基甲氧基-1,1'-联萘].该聚合物上的MOM保护基通过酸脱除获得手性螺旋聚合物聚[(S)-3-乙烯基-2,2'-二羟基-1,1'-联萘].将手性螺旋聚合物聚[(S)-3-乙烯基-2,2'-二羟基-1,1'-联萘]与Ti(O-i-Pr)4形成的配合物应用于三乙基铝与醛的不对称加成反应中,获得了较好的对映选择性,ee值最高为85%.更重要的是,这种聚合物还可以被回收利用多次且催化活性没有明显降低.

( S)-3-Vinyl-2,2'-bis( methoxmethyloxy)-1,1'-binaphthyl were synthesized via Wittig reaction. Poly-[(S)-3-vinyl-2,2'-bis(methoxmethyloxy)-1,1'-binaphthyl]which were obtained by the monomer(S)-3-vinyl-2,2'-bis( methoxmethyloxy)-1,1'-binaphthyl were radically polymerized using AIBN as initiators. The protecting groups MOM of Poly-[( S)-3-vinyl-2,2'-bis-( methoxmeth- yloxy)-1,1'-binaphthyl] were finally removed by acid treatment to afford Chiral helical polymer poly[( S)-3-vinyl-2,2'-dihydroxyl-1,1'-binaphthyl]. Titanium-poly[( S)-3-vinyl-2,2'--dihydroxyl-1,1'--binaphthyl] complexes were used to induce the enantioselective addition of triethylaluminium to aldehydes,giving up to 85 % ee of the products. Moreover,The chiral polymer can be easily recovered and reused without loss of catalytic activity as well as enantioselectivity.