On the Use of Triarylsilanols as Catalysts for Direct Amidation of Carboxylic Acids

TY - JOUR

T1 - On the Use of Triarylsilanols as Catalysts for Direct Amidation of Carboxylic Acids

AU - Braddock, D. Christopher

AU - Rowley, Ben C.

AU - Lickiss, Paul D.

AU - Fussell, Steven J.

AU - Qamar, Rabia

AU - Pugh, David

AU - Rzepa, Henry S.

AU - White, Andrew J.P.

N1 - Funding Information: We thank The Pharmacat Consortium and Pfizer for a studentship (to B.C.R), the Punjab Educational Endowment Fund (PEEF) for financial support (to R.Q.), and Jian Kwan for the initial preparation and crystallization of ester 7 . We thank the EPSRC for the grant EP/T030534/1 (to H.S.R.). Publisher Copyright: © 2023 The Authors. Published by American Chemical Society.

PY - 2023/7/21

Y1 - 2023/7/21

N2 - Triarylsilanols have been reported as the first silicon-centered molecular catalysts for direct amidation of carboxylic acids with amines as identified after a screen of silanols, silanediols, disiloxanediols, and incompletely condensed silsesquioxanes as potential homogeneous catalysts. Subsequent synthesis and testing of various electronically differentiated triarylsilanols have identified tris(p-haloaryl)silanols as more active than the parent triarylsilanol, where the bromide congener is found to be the most active. Catalyst decomposition can be observed by NMR methods, but RPKA methods reveal that product inhibition is operative, where tertiary amides are more inhibitory than secondary amides. Studies using an authentically synthesized triaryl silylester as a putative intermediate in the catalytic system enable a plausible mechanism to be proposed as supported by computationals.

AB - Triarylsilanols have been reported as the first silicon-centered molecular catalysts for direct amidation of carboxylic acids with amines as identified after a screen of silanols, silanediols, disiloxanediols, and incompletely condensed silsesquioxanes as potential homogeneous catalysts. Subsequent synthesis and testing of various electronically differentiated triarylsilanols have identified tris(p-haloaryl)silanols as more active than the parent triarylsilanol, where the bromide congener is found to be the most active. Catalyst decomposition can be observed by NMR methods, but RPKA methods reveal that product inhibition is operative, where tertiary amides are more inhibitory than secondary amides. Studies using an authentically synthesized triaryl silylester as a putative intermediate in the catalytic system enable a plausible mechanism to be proposed as supported by computationals.

UR - http://www.scopus.com/inward/record.url?scp=85165719147&partnerID=8YFLogxK

U2 - 10.1021/acs.joc.3c00585

DO - 10.1021/acs.joc.3c00585

M3 - Article

AN - SCOPUS:85165719147

SN - 0022-3263

VL - 88

SP - 9853

EP - 9869

JO - JOURNAL OF ORGANIC CHEMISTRY

JF - JOURNAL OF ORGANIC CHEMISTRY

IS - 14

ER -