Preparation of Multisubstituted Enamides via Rhodium-Catalyzed Carbozincation and Hydrozincation of Ynamides

Abstract

Rhodium-catalyzed carbozincation of ynamides using diorganozinc reagents or functionalized organozinc halides is described. Using a tri(2-furyl)phosphine-modified rhodium catalyst, the reaction course is altered to hydrozincation when diethylzinc is employed as the organozinc reagent. Trapping of the alkenylzinc intermediates produced in these reactions in further functionalization reactions is possible. Collectively, these processes enable access to a range of multisubstituted enamides in stereo- and regiocontrolled fashion.

Ynamides: A Modern Functional Group for the New Millennium

“…In an effort to improve upon this, Lam84 recently communicated their efforts on a rhodium-catalyzed carbozincation of ynamides. A representative example is shown in Scheme 55 in which ynamide 190 reacts with alkylzinc bromide 191 containing an ester moiety yielding the substituted enamide 192 .…”

Recent advances in transition-metal-catalyzed intermolecular carbomagnesiation and carbozincation

“…The reaction smoothly proceeded under mild conditions to provide the corresponding intermediate 2i regioselectively (Scheme 14) [77–78]. A wide variety of ynamides and organozinc reagents could be used for the reaction (Table 2).…”

Recent advances in carbocupration of α-heterosubstituted alkynes

“…Although not a copper-mediated transformation, the rhodium-catalyzed carbozincation of ynamides should be noted since the regioselectivities were, in general, high (>19:1), though in some cases somewhat diminished with Me 2 Zn (5:1) [26–27]. The rhodium-catalyzed annulation of ynamides with arylboron compounds containing an aldehyde or a ketone moiety have also been developed and lead to functionalized 2-amidoindenes with good levels of regioselectivity [28].…”