Transition-metal-free iterative two-fold reductive coupling and 1,3-borotropic shift to form 1,4-skipped dienes.

We report herein a transition-metal-free two-fold reductive coupling between prenal (allyl) tosylhydrazone and boronic acids/1,3-borotropic shift cascade to furnish 1,4-skipped dienes. In this work, a single batch operation produces (,)-1,4-skipped dienes by undergoing a second reductive coupling of the transient boronic acid, which developed following the first reductive allylation and a cascade 1,3-boron migration. Remarkably, the protocol is compatible with various aryl- and alkyl-substituted boronic acids, is scalable and has demonstrated on 61 substrates with yields up to 98%.

An HFIP-assisted, cobalt-catalyzed three-component electrophilic C-H amination/cyclization/directing group removal cascade to naphtho[1,2-d]imidazoles.

A concise and efficient method has been developed herein for the synthesis of valuable naphtho[1,2-d]imidazole derivatives. It involves an earth-abundant cobalt-catalyzed electrophilic C-H amination/cyclization/directing group removal cascade with -benzoloxyamines using paraformaldehyde as a one carbon synthon. Picolinamide has been utilized as a traceless directing group.

Palladium-Catalyzed Ortho C-H Arylation of Aniline Carbamates with Diazonium Salts under Mild Conditions: Expedient Synthesis of Carbazole Alkaloids.

Despite the significant progress, C-H arylation with aryldiazonium salts is a major challenge because of the faster rate of oxidative addition compared to the C-H insertion, leading to a deleterious homocoupling product. Recently, this limitation has been overcome by merging a photoredox catalyst with transition-metal catalysts which proceeds through a distinct single electron-transfer mechanism. However, we have observed that the photoredox catalyst is not necessary for the C-H arylation of aniline rather chemical reactivity can be controlled by tuning the electronic nature of the substrate.