Molbank 2024 Supporting information.pdf

: Two regioisomers of spirocyclohexenedienone g-lactams 1a and 1b were synthesized from a xanthate precursor 4 via free radical reaction, obtaining different ratios to reaction temperature (-45 °C to 150 °C), maximum regioisomeric ratio was 1:2 at 110-125 °C. Regioselectivity study suggest that products are a result of the stability of their radical precursors. Intermediate precursor of regioisomer 1b is a double a,b-unsaturated carbonyl radical which is thermodynamically stable, whereas precursor of regioisomer 1a is a,b,g,d-unsaturated carbonyl which is kinetically favoured. Spirocyclohexenedienone g-lactams were characterized by 1H and 13C RMN and x-ray diffraction crystals 1a (CCDC: 1050852) and 1b (CCDC: 1050853).</p