Aryl Thiocyanate as an Organic 'CN' Source: Access to Thiocyano-Thioesters from Cyclic Thioacetals.

A facile, transition metal-free method has been developed for the synthesis of thiocyano-thioesters. It employs cyclic thioacetals and aryl thiocyanate as an organic 'CN' source, facilitated by organophotocatalyst under the visible light irradiation. Additionally, the diaryl disulfide by-products have been efficiently repurposed as a recyclable and reusable substrates for the sustainable synthesis of aryl thiocyanates, supporting the circular chemical economy.

Visible-Light-Induced Copper-Catalyzed Radical Reactions of Diazo Arylidene Succinimides to Access the Pyromellitic Diimide (PMDI) Core.

The synthesis of pyromellitic diimides (PMDIs) through visible-light-promoted copper-catalyzed reaction of diazo arylidene succinimides has been accomplished without the use of external oxidants. This transformation involves a carbon radical from diazo arylidene succinimides with a copper catalyst or photocatalyst via the proton-coupled electron transfer (PCET) process. This approach successfully challenges a long-standing paradigm in the synthesis of PMDIs.

Visible Light-Induced Organophotoredox-Catalyzed β-Hydroxytrifluoromethylation of Unactivated Alkenes.

Herein, we report a mild transition metal-free organophotoredox-catalyzed approach for β-hydroxytrifluoromethylation of unactivated alkenes using CFSONa and acridinium salt. The protocol is compatible with various mono-, di-, and trisubstituted aliphatic unactivated alkenes containing numerous functional groups and natural product derivatives. Further, the postsynthetic modifications of the synthesized trifluoromethylated products have been demonstrated through cross-coupling and functional group interconversion reactions.

Base Dependent Rearrangement of Dithiane and Dithiolane under Visible-light Photoredox catalysis.

The rearrangement of dithiolanes and dithianes to access disulfide-linked-dithioesters under visible-light photoredox catalysis via controlled C-S bond cleavage has been disclosed. Unlike, the usual deprotection of dithioacetals to corresponding aldehydes under the oxidative conditions, we observed unique regioselective oxidative reactivity of five and six membered cyclic dithioacetals to form disulfide-linked-dithioesters by exchanging DMAP and imidazole bases. The generality of the protocol has been demonstrated by exploring a wide range of substrates.

Direct synthesis of 1,3-dithiolanes from terminal alkynes visible light photoredox catalysis.

A visible light-mediated, metal-free, regioselective dihydrothionation of terminal aromatic as well as heteroaromatic alkynes has been achieved using Eosin Y as a photoredox catalyst at room temperature. The protocol gives direct access to different 1,3-dithiolanes under neutral and mild reaction conditions without the use of any base or additives. The electron-donating, electron-withdrawing and electron-deactivating groups tolerated the photocatalytic reaction conditions.

Synthesis of Concave and Vaulted 2-Pyran-Fused BINOLs and Corresponding [5] and [7]-Oxa-helicenoids: Regioselective Cascade-Concerted Route and DFT Studies.

Synthesis of concave and vaulted 2-pyran-fused BINOLs has been achieved. A regioselective, path-breaking concerted cascade route allows the placement of six-membered heteroaromatic rings at the sterically crowded 7,8 and 7',8' positions of BINOL. DFT studies with relative energetics that support the kinetically controlled reaction pathway are preferred, matching the experimental results.