Modular allylation of C(sp3)−H bonds by combining decatungstate photocatalysis and HWE olefination in flow

Abstract

The late-stage introduction of allyl groups provides an opportunity to synthetic organic chemists for subsequent diversification, providing rapid access to new chemical space. Here, we report the development of a modular synthetic sequence for the allylation of strong aliphatic C(sp3)–H bonds. Our sequence features the merger of two distinct steps to accomplish this goal, including a photocatalytic Hydrogen Atom Transfer and an ensuing Horner-Wadsworth-Emmons reaction. This practical protocol enables the modular and scalable allylation of valuable building blocks and medicinally relevant molecules.

Photocatalytic Deoxygenative Alkylation of C(sp3)−H Bonds Using Sulfonylhydrazones

“…[21][22][23][24] Notably, these N-sulfonyl hydrazones can be exploited as a suitable electrophilic site for both polar and radical addition to yield, upon dinitrogen and sulfinate extrusion, the targeted C(sp 3 )-C(sp 3 ) bonds. [25][26][27][28][29][30][31][32] To realize a metalfree protocol, we anticipated that a photocatalytic Hydrogen Atom Transfer (HAT) strategy would be appealing to activate aliphatic C-H bonds, [33][34][35][36][37][38][39][40][41][42][43][44][45] thus generating from cheap commodity chemicals the required nucleophilic radicals which can subsequently add to the polarity-matched N-sulfonyl hydrazone. Herein, we describe the realization of such a photocatalytic deoxygenative alkylation of N-sulfonyl hydrazones using diarylketones as the photocatalyst (Figure 1b).…”

Membrane-based TBADT recovery: increasing the sustainability of continuous-flow photocatalytic HAT transformations

“…To achieve this selectivity, careful tuning of the steric and electric properties of the HAT photocatalyst and substrate has to take place. Among the limited selection of photocatalysts promoting HAT, arguably the most versatile HAT photocatalyst is the decatungstate anion, which found application in a wide range of transformations, including alkylation, [3][4][5][6][7][8] arylation, 9 acylation, 10 amination [11][12][13][14] , fluorination, [15][16][17] trifluoromethylation, 18 sulfinylation 19 and oxygenation (Scheme 1A). 20,21 Despite the potential of TBADT for synthetic applications, the adoption of photocatalytic HAT in industrial processes is still limited.…”