The allylation of the β-siloxyacetal (5), (S–R,R isomer) in the presence of TiCl4 gave the chelation adduct (6) with very high selectivity, while the (R–R,R) isomer (8) also produced the chelation adduct (9), indicating that the 1,3-asymmetric induction is dictated by chelation rather than the acetal template.
的β-siloxyacetal(烯丙基化5),(小号- - [R ,- [R异构体)在的TiCl存在4得到螯合加合物(6)具有非常高的选择性,而([R - - [R ,- [R )异构体(8)还产生了螯合加合物(9),表明1,3-不对称诱导是由螯合而不是
乙缩醛模板决定的。