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Title: Why Does Alkylation of the N–H Functionality within M/NH Bifunctional Noyori-Type Catalysts Lead to Turnover?

Abstract

Molecular metal/NH bifunctional Noyori-type catalysts are remarkable in that they are among the most efficient artificial catalysts developed to date for the hydrogenation of carbonyl functionalities (loadings up to ~10 –5 mol %). In addition, these catalysts typically exhibit high C$=$O/C$=$C chemo- and enantioselectivities. This unique set of properties is traditionally associated with the operation of an unconventional mechanism for homogeneous catalysts in which the chelating ligand plays a key role in facilitating the catalytic reaction and enabling the aforementioned selectivities by delivering/accepting a proton (H +) via its N–H bond cleavage/formation. A recently revised mechanism of the Noyori hydrogenation reaction (Dub, P. A. et al. J. Am. Chem. Soc. 2014, 136, 3505) suggests that the N–H bond is not cleaved but serves to stabilize the turnover-determining transition states (TDTSs) via strong N–H···O hydrogen-bonding interactions (HBIs). Here, the present paper shows that this is consistent with the largely ignored experimental fact that alkylation of the N–H functionality within M/NH bifunctional Noyori-type catalysts leads to detrimental catalytic activity. Finally, the purpose of this work is to demonstrate that decreasing the strength of this HBI, ultimately to the limit of its complete absence, are conditions under which the same alkylation may leadmore » to beneficial catalytic activity.« less

Authors:
ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]
  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Publication Date:
Research Org.:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org.:
USDOE Laboratory Directed Research and Development (LDRD) Program
OSTI Identifier:
1364541
Report Number(s):
LA-UR-16-24877
Journal ID: ISSN 0002-7863; TRN: US1702322
Grant/Contract Number:  
AC52-06NA25396; AC04-94AL85000
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Journal of the American Chemical Society
Additional Journal Information:
Journal Volume: 139; Journal Issue: 3; Journal ID: ISSN 0002-7863
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Inorganic and Physical Chemistry; Organic Chemistry

Citation Formats

Dub, Pavel, Gordon, John Cameron, and Scott, Brian Lindley. Why Does Alkylation of the N–H Functionality within M/NH Bifunctional Noyori-Type Catalysts Lead to Turnover?. United States: N. p., 2017. Web. doi:10.1021/jacs.6b11666.
Dub, Pavel, Gordon, John Cameron, & Scott, Brian Lindley. Why Does Alkylation of the N–H Functionality within M/NH Bifunctional Noyori-Type Catalysts Lead to Turnover?. United States. doi:10.1021/jacs.6b11666.
Dub, Pavel, Gordon, John Cameron, and Scott, Brian Lindley. Wed . "Why Does Alkylation of the N–H Functionality within M/NH Bifunctional Noyori-Type Catalysts Lead to Turnover?". United States. doi:10.1021/jacs.6b11666. https://www.osti.gov/servlets/purl/1364541.
@article{osti_1364541,
title = {Why Does Alkylation of the N–H Functionality within M/NH Bifunctional Noyori-Type Catalysts Lead to Turnover?},
author = {Dub, Pavel and Gordon, John Cameron and Scott, Brian Lindley},
abstractNote = {Molecular metal/NH bifunctional Noyori-type catalysts are remarkable in that they are among the most efficient artificial catalysts developed to date for the hydrogenation of carbonyl functionalities (loadings up to ~10–5 mol %). In addition, these catalysts typically exhibit high C$=$O/C$=$C chemo- and enantioselectivities. This unique set of properties is traditionally associated with the operation of an unconventional mechanism for homogeneous catalysts in which the chelating ligand plays a key role in facilitating the catalytic reaction and enabling the aforementioned selectivities by delivering/accepting a proton (H+) via its N–H bond cleavage/formation. A recently revised mechanism of the Noyori hydrogenation reaction (Dub, P. A. et al. J. Am. Chem. Soc. 2014, 136, 3505) suggests that the N–H bond is not cleaved but serves to stabilize the turnover-determining transition states (TDTSs) via strong N–H···O hydrogen-bonding interactions (HBIs). Here, the present paper shows that this is consistent with the largely ignored experimental fact that alkylation of the N–H functionality within M/NH bifunctional Noyori-type catalysts leads to detrimental catalytic activity. Finally, the purpose of this work is to demonstrate that decreasing the strength of this HBI, ultimately to the limit of its complete absence, are conditions under which the same alkylation may lead to beneficial catalytic activity.},
doi = {10.1021/jacs.6b11666},
journal = {Journal of the American Chemical Society},
issn = {0002-7863},
number = 3,
volume = 139,
place = {United States},
year = {2017},
month = {1}
}

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