Radical vinylation of dioxolanes and N-acylpyrrolidines using vinyl bromides

Abstract

Radical vinylation of 1,3-dioxolanes and N-acylpyrrolidines using vinyl bromides with an electron-withdrawing substituent proceeded well to give the vinylated products.

Bromine as a Visible-Light-Mediated Polarity-Reversal Catalyst for the Functionalization of Aldehydes

“…In light of all experimental data and previous literature reports, [35][36][37][38]50 plausible mechanistic pathways for photo-mediated bromine-catalyzed PRC reactions are proposed and illustrated in Fig. 4b.…”

“…11,[33][34][35][36][37] In this context, Ryu et al have developed various attractive bromine-radical mediated transformations. [35][36][37] Very recently, the Miyake group described an excellent study of bromine radical catalysis promoted by energy transferring photosensitization. 38 Our group has reported photo-induced selective tertiary C(sp 3 )-H alkylation and amination using CH 2 Br 2 as a bromine radical precursor.…”

“…In stark contrast, bromine reagents have not been utilized in PRC reactions, but bromine radical (Br•) is well known as a moderately electrophilic HAT agent, which can abstract hydrogen atoms from C-H bonds to form nucleophilic carbon radicals. 11,[33][34][35][36][37] In this context, Ryu et al have developed various attractive bromine-radical mediated transformations. [35][36][37] Very recently, the Miyake group described an excellent study of bromine radical catalysis promoted by energy transferring photosensitization.…”

A Palladium/Light System Combined with Hanztsch Ester: Radical Vinylation of Alkyl Iodides with Vinyl Bromides

“…The reactions of primary,s econdary,a nd tertiary alkyl iodides 1b, 1c, 1d and 1f with 2b all gave the E-isomer products 3c, 3d, 3e and 3f in good yields ( Table 2, entries 2-5). Phenyl-substituted vinyl bromide 2c reactedw ith alkyl iodides 1a, 1b,a nd 1c to give the corresponding E-isomer products 3g, 3h,a nd 3i,a lthough the yields require furthero ptimization( Ta ble 2, entries [6][7][8]. The reaction of cyano-substituted vinyl bromide 2d workedw ellt og ive alkenes 3j, 3k,a nd 3l,i nw hich Z-isomers were formed predominantly (Table 2, entries 9-11).…”

“…[6] The first step of the Pd/light system is SET between Pd 0 and R-I to form the RC and Pd I -I pair and we thought that the Pd/ light system would thus be usefula lso for radicalv inylation employing vinyl bromides. [7] To achieve the equivalent reaction of the Mizoroki-Heck reaction of alkyl halides [Eq. (1), Scheme 1],w ep ostulated that the Pd/light-induced radical addition/fragmentation sequence was promising [ Eq.…”