From reagents to feedstocks: reprogramming heteroatom-containing molecules in modern organic synthesis.

The boundary between reagents and feedstocks in organic synthesis has traditionally been rigid, with heteroatom containing molecules serving primarily as stoichiometric reagents that generate waste. Recent advances in transition-metal catalysis, organocatalysis, and photoredox chemistry have begun to reprogram these molecules into atom-economical feedstocks whose heteroatom content is deliberately incorporated into products. This review develops a systematic feedstock design matrix that integrates structural prerequisites, electronic roles, and thermodynamic logic to identify viable candidates, exemplified by sulfur dioxide, ammonia, carbon dioxide, and DMSO. We highlight how catalytic strategies transition metal, organocatalytic, and photoredox platforms activate heteroatom feedstocks across diverse reactivity modes including decarboxylative, atom-retentive, radical, nucleophilic, and bifunctional pathways. The survey emphasizes intersections between these modes, demonstrating how dual and cooperative catalysis expand synthetic scope and efficiency. By consolidating mechanistic insights and practical advances, this review establishes feedstock reprogramming as a unifying principle in modern synthesis, with broad implications for pharmaceuticals, materials, and sustainable chemical production.