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Organocatalytic Coupling of CO 2 with a Propargylic Alcohol: A Comprehensive Mechanistic Study
Author(s) -
Boyaval Amélie,
Méreau Raphaël,
Grignard Bruno,
Detrembleur Christophe,
Jerome Christine,
Tassaing Thierry
Publication year - 2017
Publication title -
chemsuschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.412
H-Index - 157
eISSN - 1864-564X
pISSN - 1864-5631
DOI - 10.1002/cssc.201601524
Subject(s) - chemistry , bifunctional , ene reaction , methylene , carbonate , catalysis , alcohol , gibbs free energy , selectivity , medicinal chemistry , organic chemistry , physics , quantum mechanics
The metal‐free coupling of a propargylic alcohol with CO 2 catalysed by guanidine derivatives was investigated in detail through the combination of online kinetic studies by in situ attenuated‐total reflection IR (ATR–IR) spectroscopy and DFT calculations. Bicyclic guanidines, namely 1,5,7‐triazabicyclo[4.4.0]dec‐5‐ene (TBD) and 7‐methyl‐1,5,7‐triazabicyclo[4.4.0]dec‐5‐ene (MTBD) are effective catalysts for the conversion of 2‐methyl‐3‐butyn‐2‐ol to α‐methylene cyclic carbonate and oxoalkyl acyclic carbonate under mild reaction conditions. The lower selectivity of TBD in comparison with MTBD towards the formation of α‐methylene cyclic carbonate was elucidated from DFT calculations and is related to the bifunctional activity (base/H‐bond donor) of TBD decreasing the Gibbs free energy of the reaction path for the formation of the acyclic carbonate.