Switching of Enantioselectivity in the Catalytic Addition of Diethylzinc to Aldehydes by Regioisomeric Chiral 1,3-Amino Sulfonamide Ligands
作者:Takuji Hirose、Kazuyuki Sugawara、Koichi Kodama
DOI:10.1021/jo200834n
日期:2011.7.1
Twenty chiral 1,3-amino sulfonamides of two classes (2a–i and 3a–k) have been prepared from (−)-cis-2-benzamidocyclohexanecarboxylic acid (1) and studied as ligands for catalytic enantioselective addition of Et2Zn to a variety of aromatic and aliphatic aldehydes. The ligands 2 and 3 are regioisomers in which the position of the amine and sulfonamide groups is exchanged. Each class of ligands with the
从(-)-顺式-2-苯甲酰胺基环己烷羧酸(1)制备了两类(2a – i和3a – k)的二十种手性1,3-氨基磺酰胺,并研究了其作为Et 2 Zn催化对映选择性加成的配体。各种芳香族和脂肪族醛。配体2和3是区域异构体,其中胺和磺酰胺基团的位置被交换。显示具有相同手性的每一类配体提供具有相反立体化学的仲醇。结构调查表明,叔氨基和p的组合-甲苯磺酰脲基对反应最有效。通过优化结构和反应条件,最佳配体定量提供了两种对映体仲醇,对(S)-和(R)-对映体的对映体选择性良好,对映体选择性分别高达94%和98%ee 。