t-Butyl 6-bromo-(E)-4-hexenoate was used as a handle for the solid-phasesynthesis of glycopeptides. The handle was first conjugated with Fmoc amino acids to form the allyl esters, which were then attached to the Sieber amide resin via acidic cleavage of the t-butyl esters followed by activation of the liberated carboxylic acids. Solid-phasesynthesis was demonstrated for the glycopeptide oligomers modeled
Synthesis of Complex Allylic Esters via C−H Oxidation vs C−C Bond Formation
作者:Nicolaas A. Vermeulen、Jared H. Delcamp、M. Christina White
DOI:10.1021/ja104826g
日期:2010.8.18
A highly general, predictably selective C H oxidation method for the direct, catalytic synthesis of complex allylic esters is introduced. This Pd(II)/sulfoxide-catalyzed method allows a wide range of complex aryl and alkyl carboxylic acids to couple directly with terminal olefins to furnish (E)-allylic esters in synthetically useful yields and selectivities (1 6 examples, EIZ L- 10:1) and without the use of stoichiometric coupling reagents or unstable intermediates. Strategic advantages of constructing allylic esters via C H oxidation vs C C bond-forming methods are evaluated and discussed in four "case studies".