(PTC = Phase-Transfer Catalysis)
Shaobo Duan, Sanliang Li, Xinyi Ye, Nuan-Nuan Du, Choon-Hong Tan and Zhiyong Jiang
The Journal of Organic Chemistry, 2015, 80, 1119–1123
Abstract: In the presence of an L-tert-leucine-derived urea–ammonium salt as phase-transfer catalyst, a highly enantioselective alkylation of 5H-oxazol-4-ones with various benzyl bromides and allylic bromides has been developed to furnish catalytic asymmetric synthesis of biologically important dialkylated α-hydroxy carboxylic acids with a broad scope. This is the first example of an L-amino acid-derived urea–ammonium salt being used as a phase-transfer catalyst with excellent catalytic efficiency.
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