1.3- Dimethoxy-1 -trimethylsilyloxy-1,3-butadiene

A related cyclocondensation using bis-1, l-dimethoxy-3-trimethylsilyloxy-1,3-butadiene provides a synthesis of 3-keto-8-lactones (equation III).4... 

Dimethoxy-l-trimethylsilyloxy-l, 3-butadiene. 1,2-Dimethoxy-1 -trimethylsily-loxy-l,3-pentadiene. Dimethyl 1,2,4,5-tetrazine-3,6-dicarboxylate. 1 -Methoxy-... 

Among the more reactive and synthetically useful dienes are doubly and triply activated alkoxy- and amino-substituted dienes, such as ( )-l-methoxy-3-(trimethylsilyloxy)-1,3-butadiene (Danishefsky s diene),( )-l-(dimethylamino)-3-(fert-butyldimethylsilyloxy)-1,3-butadiene (Rawal s diene)-, and 1,3-dimethoxy-l-(trimethylsilyloxy)-1,3-butadiene (Brassard s diene). As illustrated below, the cyclo-addition products arising from these dienes can either be hydrolyzed or treated with fluoride ion to remove the silyl group, which is followed by (3-elimination to provide conjugated cyclohexenones. 

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