Deaminative (Carbonylative) Alkyl‐Heck‐type Reactions Enabled by Photocatalytic C−N Bond Activation

Abstract

The palladium-catalyzed Heck reaction is aw ellknown, Nobel Prizew inning transformation for producing alkenes.U nlike the alkenyl and aryl variants of the Heck reaction, the alkyl-Heck reaction is still underdeveloped owing to the competitive side reactions of alkyl-palladium species. Herein, we describe the development of ad eaminative alkyl-Heck-type reaction that proceeds through C À Nb ond activation by visible-light photoredoxcatalysis.Avariety of aliphatic primary amines were found to be efficient starting materials for this new process,affording the corresponding alkene products in good yields under mild reaction conditions.M oreover,t his strategy was successfully applied to deaminative carbonylative alkyl-Heck-type reactions.

Ni-catalyzed deaminative cross-electrophile coupling of Katritzky salts with halides via C─N bond activation

“…Next, we examined whether alkynyl halides could also participate in this Ni-catalyzed cross-electrophile coupling reaction to construct C(sp 3 )─C(sp) bonds. Such transformations have never been explored with primary amines (23)(24)(25)(26)(27)(28)(29)(30). After careful screening of the nickel catalysts and ligands, we found that the reaction of (bromoethynyl) triisopropylsilane and 1-phenethyl-2,4,6-triphenylpyridinium tetrafluoroborate with the combination of Ni(acac) 2 /dtbpy L1 as catalyst afforded alkyne 23 in 67% yield (68% from the in situ reaction).…”

Photoinduced C(sp3)−N Bond Cleavage Leading to the Stereoselective Syntheses of Alkenes

“…[18] These impressive achievements indicate that the alkyl radical generation protocol by CÀNc leavage can open up conceptually new synthetic routes.A st he latest development in our work on CÀNb ondc leavage protocols, [13] we herein reporto ur results on C(sp 3 )ÀNb ond-cleavage-type MÀH reactions with alkyl Katritzkys alts by ap hotoredoxc atalytic process, affording alkyl-substituted alkenesw ith high yields and selectivity (Scheme 1). [19] Our basic concept was as follows. First, Katritzky salts 1 would react with the excited photocatalyst( PC) through an SEredoxp rocess, [18] releasinga lkyl radical A and 2,4,6-triphenylpyridine (through aromatizingh omolysis of the CÀNb ond),t ogether with oxidized PC + species.…”

N-Heterocyclic carbene-catalyzed deaminative cross-coupling of aldehydes with Katritzky pyridinium salts

“…Recently, Katritzky pyridinium salts, easily prepared from the condensation of primary amines with commercially available pyrylium salts, have emerged as a powerful tool for the generation of alkyl radical species. 3 Watson, 4 Glorius, 5 Aggarwal, 6 Shi, 7 Gryko, 8 Xiao, 9 Martin, 10 Rueping, 11 and Molander 12 have demonstrated the utility of Katritzky salts to form various types of C-C and C-B bonds via deaminative cross-coupling under Nicatalyzed or photomediated conditions (Scheme 1a). Despite the impressive achievements in this eld, a synthetic method that efficiently transforms an amine functionality into a carbonyl group via a deaminative radical pathway is still underexplored.…”