Palladium-Catalyzed Room-Temperature Acylative Suzuki Coupling of High-Order Aryl Borons with Carboxylic Acids

Abstract

This note describes a dimethyl dicarbonate-assisted, Pd(OAc)2/PPh3-catalyzed acylative Suzuki coupling of carboxylic acids with diarylborinic acids or tetraarylboronates for practical and efficient synthesis of sterically undemanding aryl ketones at room temperature. More than just cost-effective alternatives to aryl boronic acids, diarylborinic acids and tetraarylboronates displayed higher reactivity in the acylative Suzuki coupling. A variety of alkyl aryl ketones, including those bearing a hydroxy, bromo, or carbonyl group, could be readily obtained in modest to excellent yields.

Recent Advances in Acyl Suzuki Cross-Coupling

“…Furthermore, recent progress by Zou in the use of high order aryl boron reagents such as diarylbornic acids and tetra-arylboronates in the acyl Suzuki cross-coupling of carboxylic acids is noteworthy (Scheme 14) [44]. These reagents are not only more cost effective than conventional boronic acids but also showed increased reactivity in the cross-coupling using DMDC activator.…”

“…Furthermore, recent progress by Zou in the use of high order aryl boron reagents such as diarylbornic acids and tetra-arylboronates in the acyl Suzuki cross-coupling of carboxylic acids is noteworthy (Scheme 14) [44].…”

“…These reagents are not only more cost effective than conventional boronic acids but also showed increased reactivity in the cross-coupling using DMDC activator. This acylative Suzuki cross-coupling had a remarkably broad substrate scope, affording products bearing hydroxy, bromo, and carbonyl groups in good to high yields [44].…”

Direct Conversion of Carboxylic Acids to Alkyl Ketones

“…8 However, only a few protocols have been reported for the highly desirable, direct conversion of carboxylic acids in transition-metal-catalyzed synthesis of ketones. Thus, although a number of elegant protocols, including in situ activation of carboxylic acids, have been disclosed by Gooßen, 9 Yamamoto, 10 and Zou, 11 they are largely limited to the synthesis of aromatic ketones. Reductive coupling of in situ activated carboxylic acids provides another means to generate aliphatic ketones, but the employment of superstoichiometric amounts of Zn or Mn as the reductant and, in some cases, the use of three to four equivalent of carboxylic acid are distinct disadvantages of these methods.…”

Palladium-Catalyzed Room Temperature Acylative Cross-Coupling of Activated Amides with Trialkylboranes

“…Early this year, Rueping and co-workers described the other nickel-catalyzed cross-coupling of B-alkyl-9-BBN with amides [ 27 ]. After extension of the nucleophile counterparts from arylboronic acids to cost-effective diarylborinic acids and tetraarylboronates in palladium-catalyzed acylative cross-coupling of amides [ 28 , 29 ], we are interested in the reactivity of trialkylboranes, which could be readily prepared from alkyl Grignard reagents or olefins via hydroboration. Herein we report a highly efficient palladium-catalyzed acylative cross-coupling of activated amides with trialkylboranes at room temperature by using 1,3-bis(2,6-diisopropyl)phenylimidazolylidene (IPr) and 3-chloropyridine (3-ClPy) co-supported palladium chloride, the PEPPSI catalyst developed by Organ et al [ 30 ].…”