An unusual formal oxy transposition of vinylogous β-silyloxy-cyclobutanone 1 (a 1,5-difunctionalized substrate) under mild acidic conditions (aqueous HF in CH3CN at 0 °C) to the decalinic γ-lactone 2 was described. A plausible mechanistic pathway involving the Grob-type fragmentation and intramolecular γ-lactonization was proposed.Download high-res image (63KB)Download full-size imageAn unusual formal oxy transposition of vinylogous β-silyloxy-cyclobutanone 1 under mild acidic conditions to the decalinic γ-lactone 2 was described. A plausible mechanistic pathway involving the Grob-type fragmentation and intramolecular γ-lactonization was proposed.

AbstractA method for the preparation of thermodynamic (4R,11bS)-benzo[a]quinolizine-2-one derivatives in good enantio- and diastereoselectivity by a one-pot oxidative formal aza-Diels–Alder reaction of 1,2,3,4-tetrahydroisoquinolines and α,β-unsaturated ketones is described. The reaction proceeds via tandem ruthenium-catalyzed amine dehydrogenation using tert-butyl hydroperoxide (TBHP) as the oxidant and a chiral thiourea-catalyzed formal aza-[4+2] cycloaddition, providing a step-economical strategy for the synthesis of these valuable heterocyclic products.