Development of sustainable methods for the activation of less reactive undirected C(sp3)–H bonds is challenging but desired in organic synthesis. The present manuscript demonstrates selective activation of acidic C(sp3)–H groups for a dehydrogenative C–H imination reaction by 4H elimination using PhI (10 mol%)–mCPBA as an organocatalyst.

Applications of organic cocrystal systems to obtain semiconductor materials with low band gap, balanced electron and hole carrier mobility, low cost, solution processability, air stability, and easy preparative route have been widely sought after in recent years. Herein, we describe two organic donor–acceptor cocrystals (T2TC1)·toluene and T1P1TC2 comprising pyrene (P), triphenylene (T) as the π-donors, and tetracyanoquinodimethane (TCNQ) (TC) as the π-acceptor exhibiting significant ambipolar semiconductor nature with charge carrier mobility values in the range 0.01–0.03 cm2 V–1 s–1. Both the cocrystals possess mixed D–A stack comprising triphenylene and TCNQ molecules, whereas the other triphenylene or pyrene molecule is inserted between adjacent mixed DA stacks. The cocrystals are characterized with appropriate band gap (1.5–2.5 eV) and lower lying lowest unoccupied molecular orbital level (−4.1 to −4.3 eV) for ambipolar charge transport, low preparation cost, solution processability which make them ideal organic semiconductor materials for practical application. Theoretical studies show that high ambipolar semiconductor nature is a result of synergism between two principal charge carrier transfer pathways in cocrystal system viz. superexchange and direct paths owing to the unique supramolecular features of cocrystals (T2TC1)·toluene and T1P1TC2.

In a chlorinative cyclization, Mes-Acr-MeClO4 acted as a visible-light photocatalyst to obtain 3-chlorocoumarins from aryl alkynoates and N-chlorosuccinimide (NCS). The radical initiated reaction proceeded in a cascading manner via Cl– addition to alkynoates. Next, 5-exo-trig spirocyclization and subsequent 1,2-ester migration led to the formation of C–C and C–Cl bonds.

Charge transfer cocrystals of 2,7-di-tert-butylpyrene donor and tetracyanoquinodimethane, tetracyanobenzene and 1,3-dinitrobenzene acceptor exhibited switchable semi-conductivity.

A visible-light-mediated sustainable approach for metal-free oxygenation of quinoxalin-2­(1H)-one by employing Mes-Acr-MeClO4 as a photocatalyst without using any additive or cocatalyst is reported here. O2 served as the eco-friendly and green oxidant source for this conversion. In addition, the protocol exhibited high regioselectivity and tolerance toward a broad spectrum of functional groups to furnish quinoxaline-2,3-diones in good to excellent yields.