AUTHOR=Guo Zhibin , Oh Daehyun , Sagong Min , Yang Jewon , Lee Geumwoo , Park Hyeung-geun 

TITLE=Synthesis of chiral malonates by α-alkylation of 2,2-diphenylethyl tert-butyl malonates via enantioselective phase-transfer catalysis

JOURNAL=Frontiers in Chemistry

VOLUME=11

YEAR=2023

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2023.1205661

DOI=10.3389/fchem.2023.1205661

ISSN=2296-2646

ABSTRACT=<p>An efficient synthetic approach for chiral malonates was established via enantioselective phase transfer catalysis. The α-alkylation of 2,2-diphenylethyl tert-butyl α-methylmalonates with (S,S)-3,4,5-trifluorophenyl-NAS bromide as a phase-transfer catalyst under phase-transfer catalytic conditions successfully produced corresponding α-methyl-α-alkylmalonates; these compounds are versatile chiral building blocks containing a quaternary carbon center in high chemical yields (up to 99%) with excellent enantioselectivities (up to 98% ee). α,α-Dialkylmalonates were selectively hydrolyzed to the corresponding chiral malonic monoacids under basic (KOH/MeOH) and acidic conditions (TFA/CH<sub>2</sub>Cl<sub>2</sub>), showing the practicality of the method.</p>