Petasis-Type gem-Difluoroallylation Reactions Assisted by the Neighboring Hydroxyl Group in Amines

Abstract

A three-component Petasis-type gem-difluoroallylation reaction of using pinacol gem-difluoroallylboronates, aldehydes or isatin, and β-amino alcohols enabled by the neighboring hydroxyl group in amine is reported, affording various racemic and chiral gem-difluorohomoallylamine derivatives with good to excellent results. Based on the control experiment and stereochemistry of the product, a proposed reaction pathway is illustrated to clarify the origin of regio- and stereoselectivity under protic solvent conditions.

gem-Difluoroallylation of Aryl Diazoesters via Catalyst-Free, Blue-Light-Mediated Formal Doyle–Kirmse Reaction

“…Synthetically useful methods via the direct gem -difluoroallylation are much less explored. Only a handful reactions based on the nucleophilic gem -difluoroallylation of aldehydes, ketones, or imides by 3,3-difluoroallylboronates, which were obtained from metal-catalyzed borylation of trifluoromethyl-substituted alkenes, have been developed . In addition, Zhang and co-workers have disclosed a highly regioselective gem -difluoroallylation of organoborons through a Pd-catalyzed cross-coupling reaction .…”

Brønsted Acid‐Catalyzed General Petasis Allylation and Isoprenylation of Unactivated Ketones

“…More importantly, the use of an increased amount of 3 a gave product 4 aa in 84 % yield (1.5 equiv; Table , entry 8). In contrast to our earlier work, the use of 4 Å molecular sieves (MS) was not required (Table , entry 9). Similarly, further increasing the amount of 3 a or conducting the reaction at 50 °C proved to be ineffective (Table , entries 10–12).…”

“…Previously, we have reported on Petasis allylboration using aldehydes, a 1,2‐amino alcohol, and pinacolyl allylboronic ester . Accordingly, we sought to extend this methodology to the use of unactivated ketones (Table ).…”

Enantioselective synthesis of α-amino esters through Petasis borono-Mannich multicomponent reaction of potassium trifluoroborate salts

“…It was suspected that the group of ethyl glyoxylate still imposes strong effect for the activation of trifluoroborate salts in the reaction. 54,55…”