Highly enantioselective hetero-Diels–Alder reaction between trans-1-methoxy-2-methyl-3-trimethylsiloxybuta-1,3-diene and aldehydes catalyzed by (R)-BINOL–Ti(IV) complex
作者:Bo Gao、Zhengyan Fu、Zhipeng Yu、Lan Yu、Yaozong Huang、Xiaoming Feng
DOI:10.1016/j.tet.2005.04.016
日期:2005.6
An efficient enantioselective approach to 2,5-disubstituted dihydropyrones was developed. Some easily accessible inexpensive diol ligand metal complexes were employed, and [(R)-BINOL]2–Ti(OiPr)4 complex was found to be the most effective catalyst (up to 99% yield and 99% ee in the presence of 5 mol% catalyst) for the hetero-Diels–Alder reaction between trans-1-methoxy-2-methyl-3-trimethylsiloxybuta-1
开发了一种对2,5-二取代的二氢吡喃酮的有效对映选择性方法。使用了一些容易获得的廉价二元醇配体金属配合物,发现[[ R ] -BINOL] 2 -Ti(O i Pr)4配合物是最有效的催化剂(在存在的情况下,收率高达99%,ee为99% 5摩尔%催化剂)用于反式-1-甲氧基-2-甲基-3-三甲基甲硅烷氧基丁1,3-二烯(1)与醛之间的杂Diels-Alder反应。通过多种醛,包括芳族,杂芳族,α,β-不饱和和脂族醛,评估了该催化剂的潜力和通用性。根据苯甲醛反应中分离出的中间体通过1 H,13 C NMR和HRMS数据表明,该机理被认为是Mukaiyama羟醛途径。