Photocatalytic C–H Disulfuration for the Preparation of Indolizine-3-disulfides

Abstract

A photocatalytic C−H disulfuration of indolizines was developed, giving an approach to a wide variety of indolizine-3-disulfides with good yields. Trisulfide dioxides were explored as a high-efficient disulfuration reagent. This disulfuration reaction could be scaled up to grams. Mechanistic studies support a photoinduced pathway involving the generation of indolizine cationic radicals. A bulky alkyl substituent on terminal sulfur of trisulfide dioxide A was necessary for selective formation of disulfide over monosulfide.

Direct C−H Sulfuration: Synthesis of Disulfides, Dithiocarbamates, Xanthates, Thiocarbamates and Thiocarbonates

“…In 2022, Cao and coworkers established an organophotocatalytic strategy for the C(sp 2 )−H disulfuration of indolizines 41 using trisulfide dioxides 4 as the disulfuration reagent, rose bengal (RB) as the photocatalyst and Cs 2 CO 3 as the base under transition‐metal‐free aerobic conditions (Scheme 13). [108] Surprisingly, an unexpected tert ‐butyl acrylate derivative 44 was formed when TBHP (5.0 equiv.) was added as an additional oxidant under air atmosphere.…”

Controlled and Site-Selective C–H/N–H Alkenylation, Dialkenylation, and Dehydrogenative β-Alkenylation of Various N-Heterocycles

“…In this field, we have developed divergent approaches to realize high site-selective C–H functionalization of indolizines during the past few years (Scheme a). For C3 functionalization, we have achieved regioselective C3 monothiolation, dicarbonylation, carboxamidation, dithiocarbamation, disulfuration, and phosphorothiolation. , For C3 and C1 difunctionalization, we have developed selective dithiolation, electrochemical diselenylation, and 1,4-S → C phospho-Fries rearrangement to deliver mercapto-phosphono-substituted indolizines . In addition, our group has also reported a metal-free, visible-light-induced intermolecular [3 + 2] cycloaddition strategy of indolizines and electron-deficient alkenes or alkynes to construct pyrrolo[2,1,5- cd ]indolizine derivatives, in which the cycloaddition occurred at C3 and C5 positions …”

Construction of β-Acetoxy or β-Hydroxyl Disulfides via Highly Regioselective Ring-Opening of Epoxides with Acetyl Masked Disulfide Nucleophiles

“…A recent study has focused on the development of prefunctionalized disulfurating reagents (RSS–LG, such as RSSTs or RSSNHTh) to insert “RSS” moieties . In 2022 and 2023, our group reported several efficient visible-light-induced or mechanochemical-induced approaches for the construction of S–S–N, S–S–C, or S–S–P bonds via free radical reactions of trisulfide dioxides (Scheme A) . Jiang’s group has made a large number of innovative and outstanding research achievements in this field .…”