Asymmetric construction of phosphono dihydropyranones from α-ketophosphonates enabled by Pd/chiral isothiourea relay
Mostafa Sayed1,2, Zhipeng Shi1, Zhi-Yong Han1
1Department of Chemistry, University of Science and Technology of China, Hefei 230026, China. hanzy2014@ustc.edu.cn.
Abstract:
A highly enantio- and diastereoselective approach has been developed for the synthesis of chiral phosphono dihydropyranones. This approach is enabled by Pd/chiral isothiourea relay catalysis under mild reaction conditions, starting from readily available benzyl bromides, CO, and α-ketophosphonates. The cascade reaction involves the generation of a ketene intermediate from Pd-catalyzed carbonylation of benzyl bromide and subsequent chiral Lewis base catalyzed formal [4 + 2] reaction. Phosphono lactone products can also be transformed to chiral 1,5-diester products in good yield and high stereoselectivity.
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