Manganese-catalysed divergent silylation of alkenes.

Transition-metal-catalysed, redox-neutral dehydrosilylation of alkenes is a long-standing challenge in organic synthesis, with current methods suffering from low selectivity and narrow scope. In this study, we report a general and simple method for the manganese-catalysed dehydrosilylation and hydrosilylation of alkenes, with Mn2(CO)10 as a catalyst precursor, by using a ligand-tuned metalloradical reactivity strategy. This enables versatility and controllable selectivity with a 1:1 ratio of alkenes and silanes, and the synthetic robustness and practicality of this method are demonstrated using complex alkenes and light olefins. The selectivity of the reaction has been studied using density functional theory calculations, showing the use of an iPrPNP ligand to favour dehydrosilylation, while a JackiePhos ligand favours hydrosilylation. The reaction is redox-neutral and atom-economical, exhibits a broad substrate scope and excellent functional group tolerance, and is suitable for various synthetic applications on a gram scale.

Selective Hydroarylation of 1,3-Diynes Using a Dimeric Manganese Catalyst: Modular Synthesis of Z-Enynes.

The transition-metal-catalyzed selective hydroarylation of unsymmetrical alkynes represents the state-of-art in organic chemistry, and still mainly relies on the use of precious late-transition-metal catalysts. Reported herein is an unprecedented MnI -catalyzed hydroarylation of unsymmetrical 1,3-diyne alcohols with commercially available arylboronic acids with predictive selectivity. This method addresses the challenges in regio-, stereo-, and chemoselectivity. It offers a general, convenient and practical strategy for the modular synthesis of multisubstituted Z-configurated conjugated enynes. This protocol is distinguished by its operational simplicity, complete selectivity, excellent functional-group compatibility, and gram-scale potential. A dimeric MnI species, Mn2 (CO)8 Br2 , was proven to be a much more efficient catalyst precursor than Mn(CO)5 Br.

Synthesis of cyclohexylidenehydrazine-fused polycyclics via a photocatalytic radical cascade reaction of 2-ethynylaldehyde hydrazones.

A general and efficient visible-light photoredox-catalyzed cascade annulation of 2-ethynylaldehyde hydrazones with α-bromo-carbonyls for the synthesis of various cyclohexylidene-hydrazine-fused polycyclic compounds is described. This protocol is characterized by a broad substrate scope, mild conditions and amenability to gram-scale synthesis.

Metal-Free Radical Oxidative Cyclization of o-Azidoaryl Acetylenic Ketones with Sulfinic Acids To Access Sulfone-Containing 4-Quinolones.

A novel one-pot synthesis of sulfone-containing 4-quinolones with easily available sulfinic acids as sulfonylating precursors is described. This reaction is characterized by mild reaction conditions, high functional-group tolerance and amenability to gram-scale synthesis.

A domino desulfurative coupling-acylation-hydration-Michael addition process for the synthesis of polysubstituted tetrahydro-4H-pyrido[1,2-a]pyrimidines.

A novel method for the synthesis of the polysubstituted tetrahydro-4H-pyrido[1,2-a]pyrimidines through a domino desulfurative coupling-acylation-hydration and Michael addition sequence was established.