C(2)-Symmetric dialkoxyphosphoramide and dialkoxythiophosphoramide derivatives of (1R, 2R)-1,2-diaminocyclohexane as chiral ligands for the titanium(IV) alkoxide-promoted asymmetric addition reactions of diethylzinc to arylaldehydes. |
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Authors: | Min Shi Xiao-Feng Wu Guobin Rong |
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Affiliation: | State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin Lu, Shanghai 200032, China. Mshi@pub.sioc.ac.cn |
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Abstract: | C(2)-Symmetric chiral diethoxyphosphoramide 4, diethoxythiophosphoramide 5, and diisopropoxyphosphoramide 6 of (1R, 2R)-1,2-diaminocyclohexane were prepared by the reactions of diethoxyphosphinic chloride, diethoxythiophosphinic chloride, and diisopropoxyphosphinic chloride with (1R, 2R)-1,2-diaminocyclohexane, respectively. They were used as catalytic chiral ligands in the asymmetric addition reactions of diethylzinc to aldehydes in the presence of titanium(IV) isopropoxide to give the corresponding sec-alcohols with 43-70% ee. Chiral ligands 4 and 5 gave the sec-alcohols with opposite absolute configuration. |
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Keywords: | diethylzinc titanium(IV) isopropoxide asymmetric addition reaction chiral phosphoramide chiral thiophosphoramide (1R, 2R)‐1,2‐diaminocyclohexane |
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