Bicyclo decene synthesis

Majetich reports a general intramolecular Lewis acid allylation protocol for the synthesis of bicy-clo[5.4.0]undecen-3-ones (168) and bicyclo[4.4.0]decen-3-ones (170), which are 1,6-addition products (Scheme 27). The same precursors, (167) and (169), when submitted to the fluoride ion cyclization protocol, also afford 1,2- and 1,4-addition products.73 Typically, ethylaluminum dichloride, a proton sponge Lewis acid, is used in order to minimize adventitious protonic desilylation. Other 0,y-unsatu-rated silanes also undergo similar intramolecular Lewis acid catalyzed additions for example, the si-lylpropargylic enones (171) undergo intramolecular cyclization to the allenylspiro system (172).74... 

The ability of a methanesulphonate substituent to function as a leaving group (compare equation 124, Section VI.E.2) in an intermediate cyclopropane permits transformation of a bicyclo[4.4,0]decene derivative into a compound with a hexahydroazulene skeleton having potential for sesquiterpene synthesis(equation 76). 

How Ang, K., Brase, S., Steinig, A.G., et al. (1996) Versatile synthesis of bicyclo[4.3.0]nonenes and bicyclo[4.4.0]decenes by a domino Heck-Diels-Alder reaction. Tetrahedron, 52,11503-28. 

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