A Stereoselective Suzuki Cross-Coupling Strategy for the Synthesis of Ethyl-Substituted Conjugated Dienoic Esters and Conjugated Dienones
作者:Stefan Bräse、Daniel Keck、Thierry Muller
DOI:10.1055/s-2006-958406
日期:2006.12
A stereoselective approach towards ethyl-substituted conjugated dienoic esters and dienones utilising a Suzuki cross-coupling reaction has been achieved. In addition, a method for their conversion into the corresponding ethyl ketones is presented.
Methyl 2-[1-[(tert-butoxycarbonyl)amino]ethyl]-4-methyloxazole-5-carboxylate (1) was synthesized with high optical purity via a Pd–catalyzed amide coupling with vinyl triflate with subsequent oxazole formation. The latter reaction proceeds via bromination of an enamide with NBS and DBU-promoted cyclization. The oxazole subunit positional isomer in a macrocyclic azole peptide was obtained in a good