Two-Carbon Homologation of Aldehydes and Ketones to α,β-Unsaturated Aldehydes
作者:Richard J. Petroski、Karl Vermillion、Allard A. Cossé
DOI:10.3390/molecules16065062
日期:——
Phosphonate reagents were developed for the two-carbonhomologation of aldehydes or ketones to unbranched- or methyl-branched α,β-unsaturatedaldehydes. The phosphonate reagents, diethyl methylformyl-2-phosphonate dimethylhydrazone and diethyl ethylformyl-2-phosphonate dimethylhydrazone, contained a protected aldehyde group instead of the usual ester group. A homologation cycle entailed condensation of the
膦酸酯试剂被开发用于醛或酮的双碳同系化为未支化或甲基支化的 α,β-不饱和醛。膦酸酯试剂,二乙基甲基甲酰基-2-膦酸酯二甲基腙和二乙基乙基甲酰基-2-膦酸酯二甲基腙,含有受保护的醛基而不是通常的酯基。同系化循环需要将试剂与起始醛缩合,然后用 1 M HCl 和石油醚的双相混合物去除二甲基腙保护基团。这种稳健的两步法适用于各种醛和酮。在缩合和脱保护步骤后,不饱和醛产物的总分离产率为 71% 至 86%。
Stereoselective Alkylation of α,β-Unsaturated Imines via C−H Bond Activation
作者:Denise A. Colby、Robert G. Bergman、Jonathan A. Ellman
DOI:10.1021/ja0584931
日期:2006.5.1
alkylation of α,β-unsaturated imines via C−H activation followed by imine hydrolysis produces tri- and tetrasubstitutedα,β-unsaturated aldehydes. In the presence of a rhodium catalyst, α,β-unsaturated N-benzyl imines derived from methacrolein, crotonaldehyde, and tiglic aldehyde undergo directed C−H activation at the β-position and react with terminal alkenes and alkynes to form the tri- and tetrasubstituted