Search

• Post-synthetic hooking of photocatalyst Rose Bengal and organocatalyst L-proline in an amine functionalized POF. • The modified framework works in a highly synergistic manner as dual photo-organo catalyst. • The bifunctional catalyst works under environmentally green visible light and can be recycled up to 10 cycles. • The high yield of the products in C-H functionalization is maintained for a wide range of tertiary amine substrates. • Based on experimental findings, a plausible reaction mechanism for the oxidative Mannich reaction is proposed. Photoredox and organo-catalysis denote powerful construction tools for new classes of carbon–carbon bonds, where incisive amalgamation of both the approaches over a single, recyclable platform can bring about synergic and eco-friendly reactions under mild conditions. Aiming at enamine-based photoredox catalysis for atom-economic and metal-free sp3 C H activation, an amide-based two-dimensional (2D) porous organic framework (POF) is devised. The pendent NH 2 groups are judiciously anchored with two catalytic stations viz. Rose Bengal and L-proline, through stepwise variation of solid phase peptide synthesis. The dual-catalyst engineered POF represents a fully organic material that synergistically performs visible-light triggered oxidative Mannich reaction to produce biorelevant heterocycle β-amino ketone in excellent yield at room temperature, using oxygen as clean and selective oxidant. Importantly, activity of this bi-functionalized catalyst compares favorably well to individual homogeneous counterparts. The covalently modified framework demonstrates economic viability via gram-scale synthesis besides admirable reusability, and proves to be effective for nineteen varieties of substrates. The photocatalytic path is detailed from efficient energy transfer from host polymer to substrate in light of experimental and theoretical studies, which provides proof-of-concept to the photo-organo combined mechanism. The material benefits heterogenising two homogeneous catalysts, besides excluding additional steps of conventional Mannich reactions, and offers a step-forward to smart and green cross-dehydrogenative coupling reactions. [ABSTRACT FROM AUTHOR]