Can an aromatic ring alter the reactions of a nearby unsaturated imide? A study of the rate and selectivity of nitrile oxide cycloaddition reactions of acryloyl derivatives of the Rebek imide benzoxazole

Cycloadditions of acryloyl derivatives of the Rebek imide benzoxazole are extraordinarily stereoselective, but have rates and regioselectivities that otherwise parallel those of a simple achiral model. It appears that the benzoxazole ring of these compounds completely shields the inner face of the nearby alkene, but has no measurable effect on the rate of reactions on the outer face. (C) 1997, Elsevier Science Ltd.