Anti-Selective Vicinal Silaboration and Diboration of Alkynoates through Phosphine Organocatalysis
摘要:
Trialkylphosphine organocatalysts have enabled anti-selective vicinal silaboration and diboration of the C-C triple bond in alkynoates to produce beta-boryl-alpha-silyl acrylates and alpha,beta-diboryl acrylates, respectively. The anti stereoselectivity was complete and robust. A variety of functional groups were tolerated in the alkynoates. The two vicinally installed heteroatom substituents of the beta-boryl-alpha-silyl acrylates and alpha,beta-diboryl acrylates could be differentiated and transformed in a stepwise manner, allowing the synthesis of a diverse array of unsymmetrical tetrasubstituted alkenes.
Phosphine organocatalysis enabled vicinal acylcyanation of alkynoates with acyl cyanides to form acrylonitrile derivatives with a tetrasubstituted alkene moiety. The acyl and cyano groups were introduced at the α and β carbon atoms, respectively, of the C–C triple bond in the alkynoates with complete regioselectivity and high anti stereoselectivity. A variety of functional groups in the acyl cyanides
Trialkylphosphine organocatalysts have enabled regioselective anti-hydroboration of internal, alkynes with pinacolborane reagents to provide (E)-disubstituted alkenylboronate compounds. The alkenyl-boronate can be used for derivatizations, such as protodeborylation, Suzuld-Miyaura coupling, conjugate reduction, and Diels-Alder reactions.
Synthesis of Ethyl Arylpropiolates through Palladium-Catalyzed Cross-Coupling Reactions of Aryl Iodides with In Situ Generated Lithium Tetrakis(ethoxycarbonylethynyl)indates