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Continuous flow organocatalyzed methoxycarbonylation of benzyl alcohol derivatives with dimethyl carbonate

Continuous flow organocatalyzed methoxycarbonylation of benzyl alcohol derivatives with dimethyl... An organocatalytic continuous flow process is presented for the preparation of non-symmetric benzyl carbonate derivatives. The procedure relies on dimethyl carbonate as a reagent and a solvent in conjunction with an organocatalyst for the selective methoxycarbonylation of diversely substituted benzylic alcohols. The reaction is optimized with benzyl alcohol as a model substrate, which emphasizes 1,4-diazabicyclo[2.2.2]octane (DABCO), 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), 2,8,9-trimethyl-2,5,8,9-tetraaza-1-phosphabicyclo[3.3.3]undecane (Verkade’s base) and phosphazene base P2-Et as suitable organocatalysts. The optimized conditions are next extended to a small library of 18 structurally diverse benzylic alcohol derivatives. High conversion (66–96%) and total selectivity (>99%) are achieved under mild conditions and short residence time, which converge toward a versatile and robust continuous flow protocol. Then, we illustrate that a set of representative benzyl methyl carbonates can be considered as stable, low toxicity surrogates of the corresponding chloroformates for the preparation of valuable benzyl N-hydroxycarbamates.Graphical abstract[graphic not available: see fulltext] http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Journal of Flow Chemistry Springer Journals

Continuous flow organocatalyzed methoxycarbonylation of benzyl alcohol derivatives with dimethyl carbonate

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Publisher
Springer Journals
Copyright
Copyright © Akadémiai Kiadó 2022
ISSN
2062-249X
eISSN
2063-0212
DOI
10.1007/s41981-022-00216-2
Publisher site
See Article on Publisher Site

Abstract

An organocatalytic continuous flow process is presented for the preparation of non-symmetric benzyl carbonate derivatives. The procedure relies on dimethyl carbonate as a reagent and a solvent in conjunction with an organocatalyst for the selective methoxycarbonylation of diversely substituted benzylic alcohols. The reaction is optimized with benzyl alcohol as a model substrate, which emphasizes 1,4-diazabicyclo[2.2.2]octane (DABCO), 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), 2,8,9-trimethyl-2,5,8,9-tetraaza-1-phosphabicyclo[3.3.3]undecane (Verkade’s base) and phosphazene base P2-Et as suitable organocatalysts. The optimized conditions are next extended to a small library of 18 structurally diverse benzylic alcohol derivatives. High conversion (66–96%) and total selectivity (>99%) are achieved under mild conditions and short residence time, which converge toward a versatile and robust continuous flow protocol. Then, we illustrate that a set of representative benzyl methyl carbonates can be considered as stable, low toxicity surrogates of the corresponding chloroformates for the preparation of valuable benzyl N-hydroxycarbamates.Graphical abstract[graphic not available: see fulltext]

Journal

Journal of Flow ChemistrySpringer Journals

Published: Jun 1, 2022

Keywords: Non-symmetric carbonates; Organocatalysis; Methoxycarbonylation; Dimethyl carbonate; Hydroxycarbamates

References