Regioselectivity of the Intramolecular Photocycloaddition of α,β-Butenolides to a Terminal Alkene

Abstract

Regioselectivity of the Intramolecular Photocycloaddition of a,b-Butenolides to a Terminal Alkene I n t r a m o l e c u l a r P h o t o c y c l o a d d i t i o n o f a,b-But eAbstract: The intramolecular [2+2] photocycloaddition of a,bbutenolides to a terminal double bond tethered to the lactone through the g-position and located at a suitable distance has been studied. The regioselectivity of the photoisomerization depends on the substitution pattern of the substrate and can be rationalized by simple theoretical calculations performed on the diradical intermediates.

Diastereoselective, Lewis acid-mediated Diels–Alder reactions of allenoic acid derivatives and 1,3-cyclopentadienes

“…31 These rules allow for a prediction of the regioselectivity, and exceptions are rare. 32 In the case of santalic acid, structure 14b corresponds to the straight cycloadduct, and the suggested structure 14a of Guerbet's acid to the crossed cycloadduct.…”