Selective 1,2‐Aminoisothiocyanation of 1,3‐Dienes Under Visible‐Light Photoredox Catalysis

Abstract

Selective three‐component 1,2‐diamination of 1,3‐dienes with concurrent introduction of two orthogonally protected amino groups remains unknown despite its significant synthetic potential. We report herein that reaction of conjugated dienes with N‐aminopyridinium salts and TMSNCS affords 1,2‐aminoisothiocyanation products in a highly chemo‐ and regio‐selective manner under mild photoredox catalytic conditions. Mechanistic studies indicate that the facile isomerization of allyl thiocyanates to allyl isothiocyanates under photocatalytic conditions is responsible for the selective formation of the observed products. The mild isomerization protocol is expected to find applications in the synthesis of allyl isothiocyanates in a broad sense.

Construction of C-N Bond via Visible-Light-Mediated Difunctionalization of Alkenes

“…This intermediate (B) undergo single-electron oxidation via the cooperative effects of the active Fe (III) species, to form the carbocation intermediate (C). Finally, the attack of an arylamine to the intermediate (C) is followed by base-mediated deprotonation to generate the difluoroalkylamination product (22).…”

“…Electron-withdrawing and electron-donating group of alkene and cyanopyridine react smoothly to give the product (26). According to the proposed mechanism, irradiation of Ir(ppy) 2 (dtbbpy)PF 6 produce an excited state Ir* which would capture a single-electron from azide to generate the azido radical intermediate (A) and reducing photocatalyst Ir II Recently, Guo et al in 2021 demonstrated a photocatalytic 1,2-diamination of 1,3-dienes (27) in the presence of N-aminopyridinium and TMSNCS to affords 1,2aminoisothiocyanation products (28) in high chemo-and regio-selective manner with broad substrate scope and good functional group tolerance (Figure 18) [22]. According to the proposed mechanism (Figure 18 An elegant method for the synthesis of β-sulfonyl amides ( 30) is reported by Zong et al in 2019 through an acid promoted photochemical reaction of styrenes (29), aryldiazonium tetrafluoroborates, sulfur dioxide, nitriles, and water (Figure 19) [23].…”

Difunctionalization of Alkenes and Alkynes via Intermolecular Radical and Nucleophilic Additions

“…The Zhu group applied this strategy for the reaction of γ-hydroxyalkenes in the synthesis of 1,2-difuctionalized compounds 26 involving the 1,4-heteroaryl group migration (Scheme 14) [35]. Zhu and coworkers developed a photoredox reaction for 1,2-difuctionalizatio dienes with N-aminopyridinium salts and TMSNCS (Scheme 16) [37]. Under the p talysis of fac-Ir(ppy)3, amino radicals derived from the N-aminopyridinium salt 1,3-dienes to form allylic radicals 30 which are oxidized to cations followed by a with TMSNCS to give difunctionalized products 29.…”

“…Under the p talysis of fac-Ir(ppy)3, amino radicals derived from the N-aminopyridinium salt 1,3-dienes to form allylic radicals 30 which are oxidized to cations followed by a with TMSNCS to give difunctionalized products 29. Zhu and coworkers developed a photoredox reaction for 1,2-difuctionalization of 1,3-dienes with N-aminopyridinium salts and TMSNCS (Scheme 16) [37]. Under the photocatalysis of fac-Ir(ppy) 3 , amino radicals derived from the N-aminopyridinium salts add to 1,3-dienes to form allylic radicals 30 which are oxidized to cations followed by a reaction with TMSNCS to give difunctionalized products 29.…”

Enantioselective Carbocyanation of 1,3-Dienes by Dual Visible-Light Photoredox and Copper Catalysis

“…有研究 显示 Ni 催化的不对称选择性氢氰化反应使 1,3-二烯烃 高值资源化 [5][6] , 得到手性烯丙基腈类化合物. 利用光引 发产生基态难以生成的高活性中间体或自由基, 实现 1,3-二烯烃的高效不对称双官能团化正在成为研究热 点 [7][8] . 最近, 华中师范大学化学学院肖文精团队 [9]…”