The reductive opening of epoxides represents an attractive method for the synthesis of alcohols, but its potential application is limited by the use of stoichiometric amounts of metal hydride reducing agents (e.g., LiAlH4). For this reason, the corresponding homogeneous catalytic version with H2 is receiving increasing attention. However, investigation of this alternative has just begun, and several issues are still present, such as the use of noble metals/expensive ligands, high catalytic loading, and poor regioselectivity. Herein, we describe the use of a cheap and easy-to-handle (cyclopentadienone)iron complex (1a), previously developed by some of us, as a precatalyst for the reductive opening of epoxides with H2. While aryl epoxides smoothly reacted to afford linear alcohols, aliphatic epoxides turned out to be particularly challenging, requiring the presence of a Lewis acid cocatalyst. Remarkably, we found that it is possible to steer the regioselectivity with a careful choice of Lewis acid. A series of deuterium labeling and computational studies were run to investigate the reaction mechanism, which seems to involve more than a single pathway.

Regiodivergent Reductive Opening of Epoxides by Catalytic Hydrogenation Promoted by a (Cyclopentadienone)iron Complex / L. Tadiello, T. Gandini, B.M. Stadler, S. Tin, H. Jiao, J.G. de Vries, L.L. Pignataro, C.M.A. Gennari. - In: ACS CATALYSIS. - ISSN 2155-5435. - 12:(2022), pp. 235-246. [Epub ahead of print] [10.1021/acscatal.1c03549]

Regiodivergent Reductive Opening of Epoxides by Catalytic Hydrogenation Promoted by a (Cyclopentadienone)iron Complex

T. Gandini
Secondo
Investigation
;
L.L. Pignataro
Penultimo
Writing – Original Draft Preparation
;
C.M.A. Gennari
Ultimo
Conceptualization
2022

Abstract

The reductive opening of epoxides represents an attractive method for the synthesis of alcohols, but its potential application is limited by the use of stoichiometric amounts of metal hydride reducing agents (e.g., LiAlH4). For this reason, the corresponding homogeneous catalytic version with H2 is receiving increasing attention. However, investigation of this alternative has just begun, and several issues are still present, such as the use of noble metals/expensive ligands, high catalytic loading, and poor regioselectivity. Herein, we describe the use of a cheap and easy-to-handle (cyclopentadienone)iron complex (1a), previously developed by some of us, as a precatalyst for the reductive opening of epoxides with H2. While aryl epoxides smoothly reacted to afford linear alcohols, aliphatic epoxides turned out to be particularly challenging, requiring the presence of a Lewis acid cocatalyst. Remarkably, we found that it is possible to steer the regioselectivity with a careful choice of Lewis acid. A series of deuterium labeling and computational studies were run to investigate the reaction mechanism, which seems to involve more than a single pathway.
iron catalysis; (cyclopentadienone)iron complexes; hydrogenation; epoxide opening; reduction;
Settore CHIM/06 - Chimica Organica
PRIN201719LPIGN_01 - Raising up Catalysis for Innovative Developments (SURSUMCAT) - PIGNATARO, LUCA LUIGI - PRIN2017 - PRIN bando 2017 - 2019
15-dic-2021
https://pubs.acs.org/doi/10.1021/acscatal.1c03549
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/890178
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