Dioxabicyclic systems

Chiral dioxabicyclic systems are selectively formed from 3,4-bisallyloxybut-1-yne derivatives under an ethylene atmosphere. A single RCM is performed when a RuCl2(PCy3)2(= CHPh) is employed, while the cascade RCM of dienyne is the major reaction with a second generation Grubbs catalyst (Scheme 5). In this case, the substitution of the allyloxy groups can selectively lead to dioxabicyclo[4.4.0]decane or to dioxabicyclo[5.3.0]decane [13]. 

I, 4-addition of alcohols to the double-bond forming anhydro sugars. This methodology was used to construct the dioxabicyclic system of the zaragozic acids [290]. 

Lakhrissi, M, Taillefutnier, C, Chaouch, A, Didieijean, C, Aubry, A, Chapleur, Y, Wittig olefination of partially protected sugar lactones a direct entry to dioxabicyclic and trioxatricyclic systems. Tetrahedron Lett., 39, 6457-6460, 1998. 

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