Suppression of racemization in the carbonylation of amino acid-derived aryl triflates
摘要:
The carbonylation of enantiopure phenylglycine-derived aryl triflates was achieved to afford 4-carboxyphenylglycine analogs with high enantiomeric excesses (88 to >99% ee). Amide analogs of phenylglycine were well-tolerated in the hydroxy- and methoxycarbonylation processes, providing efficient access to benzoic acid and ester building blocks. The % ee of the product was dependent on the relative steric bulk of both the amino acid substrate and the requisite amine base, with (Pr2NEt)-Pr-i proving optimal in minimizing product racemization. (c) 2007 Elsevier Ltd. All rights reserved.
Suppression of racemization in the carbonylation of amino acid-derived aryl triflates
摘要:
The carbonylation of enantiopure phenylglycine-derived aryl triflates was achieved to afford 4-carboxyphenylglycine analogs with high enantiomeric excesses (88 to >99% ee). Amide analogs of phenylglycine were well-tolerated in the hydroxy- and methoxycarbonylation processes, providing efficient access to benzoic acid and ester building blocks. The % ee of the product was dependent on the relative steric bulk of both the amino acid substrate and the requisite amine base, with (Pr2NEt)-Pr-i proving optimal in minimizing product racemization. (c) 2007 Elsevier Ltd. All rights reserved.