Chemoselective phosphine-catalyzed cascade [2 + 2 + 2] and [2 + 2 + 1] annulations between two molecules of 2-arylmethylidene cyanoacetates or malononitriles and one molecule of α,β-unsaturated ketones have been developed. Under the nucleophilic catalysis of PPh3 or PBu3 (10 mol%), a highly diastereoselective synthesis of polysubstituted cyclohexanes or cyclopentenes has been successfully achieved, respectively.
化学选择性的膦催化级联[2 + 2 + 2]和[2 + 2 + 1]环化反应已经开发出来,这些反应涉及两分子2-芳甲亚基
氰乙酸酯或
丙二腈与一分子的α,β-不饱和酮。在PPh3或PBu3(10 mol%)的亲核催化下,分别成功实现了高度对映选择性的多取代
环己烷或
环戊烯的合成。