Photochemical studies on 5-methylbicyclo[1.1.1]pentane derivatives: P-orbital overlap controlled enantioselectivity

The first example of the p-orbital overlap controlled enantioselectivity of Norrish type II photocyclization reaction was described. Irradiation of 5-methyl bicyclo[1.1.1]pentanyl ketone with UV in the solid state as well as in the acetonitrile solution afforded the Norrish/Yang photocyclization compound as the sole product. Solid-state asymmetric photochemical studies using ionic chiral auxiliary technique led to the enantioselectivity as high as 60%. The results were rationalized by X-ray single crystal structure.