Facial diastereoselectivity in the [2+2]-photocycloaddition of N,N-diallylamines

The stereoselective synthesis of 3-azabicyclo[3.2.0]heptanes 3, 4 and 7 by an intramolecular [2+2]-photocycloaddition is described. The facial diaster eoselectivity of the reaction is low for methoxycarbonyl as the alpha -subs tituent. It is high if the alpha -substituent is connected to the nitrogen atom via an oxazolidinone ring. The photocycloaddition can be conducted as a triplet-sensitized reaction for the N-cinnamyl substituted substrates 2, 6a and 6b and as a Cu(OTf)(2)-catalyzed process representing a more general method for the substrates 6a-6g.