Danishefsky’s diene

Danishefsky’s diene (Kitahara diene) is an organic compound and a diene with the formal name trans-1-methoxy-3-trimethylsilyloxy-l,3-butadiene. Because the diene is very electron-rich it is used as a very reactive reagent in Diels-Alder reactions. The OMe group allows for the Diels-Alder reaction to be made regiospecific, since the electrophilic carbon to which it is attached will react preferentially with the most nucleophilic atom of a dienophile.

Its first reported synthesis was by reaction of trimethylsilyl chloride with 4-methoxy-3-buten-2-one and zinc chloride :



Its reaction with maleic anhydride is a fast one.

In a reaction with an alkene the silyl ether is a synthon for a carbonyl group through an enol while the ether group is susceptible to an elimination reaction and capable of forming a new alkene group. In addition high regioselectivity is obtained with unsymmetrical alkenes with a preference for an 1,2-relation of the ether group with the electron-deficient alkene-carbon. All this is exemplified in this Aza Diels-Alder reaction :