New Chiral Monophosphite Ligands Containing BINOL and/or H8-BINOL Bearing Adamantyl Substituents: Effect of Ligand Scaffold on the Enantioselective 1,4-Conjugate Addition of Diethylzinc to Cyclic Enones

A series of new bulky monophosphite ligands were synthesized from axially chiral BINOL/H8-BINOL (BINOL: 1-(2-hydroxynaphthalen-1-yl)naphthalen-2-ol) and highly sterically hindered adamantylcarbonyl chloride. The effectiveness of these ligands was evaluated by the Cu-catalyzed asymmetric 1,4-conjugate addition of diethylzinc to cyclic enones with enantioselectivities of up to 79% ee. The results showed that a ligand structure comprising a partially hydrogenated 2,2′ -(1,1′ -binaphthyl)phosphite scaffold and an adamantyl moiety was effective in improving the enantioselectivity.

摘要： 以轴手性的 BINOL/H8-BINOL (BINOL 为联苯酚) 和大位阻的金刚烷酰氯为原料, 合成了系列新型手性单齿亚磷酸酯配体, 并应用于 Cu 催化的二乙基锌对环烯酮的不对称1,4-共轭加成反应中. 结果表明, 配体结构中部分氢化的 2,2′-(1,1′-联萘基) 亚磷酸酯单元和金刚烷基团, 有助于改善反应的对映选择性, 对映选择性最高可达 79%.

Graphical abstractA series of new bulky monophosphite ligands derived from BINOL/H8-BINOL and adamantanecarbonyl chloride were used in the copper-catalyzed enantioselective 1,4-conjugate addition of diethylzinc to cyclic enones (up to 79% ee).Figure optionsDownload full-size imageDownload as PowerPoint slide