Cross-dehydrogenative Coupling Reactions Between Formamidic C(sp2)-H and X-H (X = C, O, N) Bonds

Hydroxysulfonylation of alkenes: an update

The direct difunctionalization of inexpensive and widely available alkenes has been recognized as a strong and straightforward tool for the rapid fabrication of complex molecules and pharmaceutical targets by introducing two different functional groups on adjacent carbon atoms of common alkene moieties in a single operation. This synthetic strategy avoids the purification and isolation of the intermediates and thus makes synthetic schemes shorter, simpler and cleaner. In this family of reactions, the hydroxysulfonylation of alkenes has emerged as an increasingly promising strategy for the synthesis of β-hydroxysulfones, which are found in many biologically important molecules and widespread applications in organic synthesis. The objective of this review is to illustrate the advancements in the field of hydroxysulfonylation of alkenes with special emphasis on the mechanistic details of the reaction pathways.

The direct difunctionalization of alkenes recognized as a straightforward tool for the rapid fabrication of complex molecules and pharmaceutical targets by introducing two different functional groups on adjacent carbon atoms of common alkene moieties.

Intermolecular difunctionalization of alkenes: synthesis of β-hydroxy sulfides

Direct difunctionalization of carbon-carbon double bonds is one of the most powerful tools available for concomitant introduction of two functional groups into olefinic substrates. In this context, vicinal hydroxysulfenylation of unactivated alkenes has emerged as a novel and straightforward strategy for the fabrication of β-hydroxy sulfides, which are extremely valuable starting materials in constructing various natural products, pharmaceuticals, and fine chemicals. The aim of this review is to summarize the most representative and important reports on the preparation of β-hydroxy sulfides through intermolecular hydroxysulfenylation of the corresponding alkenes with special emphasis on the mechanistic features of the reactions.

Cooperative Interplay of Brønsted Acid and Lewis Acid Sites in MIL-101(Cr) for Cross-Dehydrogenative Coupling of C-H Bonds

Cross-dehydrogenative coupling (CDC) is an effective tool for carbon-carbon bond formation in chemical synthesis. Herein, we report a metal-organic framework (MOF) possessing dual Lewis acidic Cr sites and sulfonic acid sites (MIL-101(Cr)-SO₃H) as an efficient catalytic material for direct cross-coupling of xanthene and different nucleophiles using O₂ as the oxidant. The highly porous structure of MIL-101(Cr)-SO₃H enables the free access of reactants to the catalytic active sites inside MOF pores. Kinetic studies indicated that the Cr sites of MOF accelerate the rate-limiting autoxidation reaction of xanthene, which synergistically work with the sulfonic acid group on MOF ligands in promoting the CDC reactions. Besides, the catalytic system shows excellent functional group compatibility, and a variety of valuable xanthene derivatives were synthesized with satisfactory yields. Furthermore, MIL-101(Cr)-SO₃H can be reused and its catalytic activity and crystal structure remain after six consecutive runs.