Stereoselective Synthesis of Highly Substituted Tetrahydrofurans through Diverted Carbene OH Insertion Reaction

Copper‐ or rhodium‐catalyzed reactions of diazocarbonyl compounds with β‐hydroxyketones give highly substituted tetrahydrofurans with excellent diastereoselectivity. Under mild conditions, the single‐step process starts as a carbene OH insertion reaction, but is diverted by an intramolecular aldol reaction. Gone astray: Copper‐ or rhodium‐catalyzed reactions of diazocarbonyl compounds with β‐hydroxyketones give highly substituted tetrahydrofurans with excellent diastereoselectivity. The single‐step reaction proceeds under mild conditions, starting as a carbene OH insertion reaction, but then diverting to an intramolecular aldol reaction.