Carbohydrates to Carbocycles: Regio- and Stereoselectivity in the Intramolecular [2+2] Photocycloaddition of Dienic 2-Enono-δ-lactones - Gómez, Ana M; Mantecón, Susana; Velazquez, Sara; Valverde, Serafín; Herczegh, Pal; López, J Cristóbal (Synlett, 1998)