Development of Bronsted Acid-Metal Bifunctional Catalyst Based on Bisamidine Framework

合理设计和开发用于不对称催化反应的高效催化剂一直是有机化学研究的热点。针对双脒骨架的空间性质和电子性质，开发了两类手性催化剂。阳离子双酰胺锌配合物作为Bronsted-Lewis结合酸，促进了α-酮酯的不对称Mukaiyama-Aldol反应。以较高的产率得到了羟醛缩合产物，但对映体选择性较低。加入具有适当酸度和膨胀性的氟醇可显著提高对映体的选择性。多核双酰胺酸锌催化了α-酮酯的不对称烷基化反应，得到了高产率和不对称选择性的产物。

The rational design and development of a highly efficient catalyst for asymmetric catalytic reaction is of ongoing considerable interest in organic chemistry. Focusing on the steric and electronic properties of the bisamidine framework, two types of chiral catalysts were developed. The cationic zinc bisamidine complex acts as a Bronsted-Lewis combined acid to promote asymmetric Mukaiyama aldol reaction of α-ketoesters. The aldol products were obtained in good yields but with low enantioselectivities. Addition of the fluoroalcohol having suitable acidity and bulkiness led to dramatic increase in enatioselectivity. The multinuclear zinc bisamidinate catalyzed asymmetric alkylation of α-ketoesters to afford the products in high yields and enantioselectivities.