LIC-KOR Promoted Formation of Conjugate Dienes as Useful Building Blocks in Palladium–Catalyzed Syntheses

It is demonstrated that a,b-unsaturated acetals can be considered a synthetic tool for transforming carbonyl derivatives into cheap and easily accessible starting materials for the construction of various and more complex structures. The lithium–potassium mixed superbase LIC-KOR induces a conjugate elimination reaction that converts a,b-unsaturated acetals into 1E-1-alkoxybuta-1,3-dienes. These derivatives can be readily metalated in situ and functionalized by reaction with electrophiles. The results can be grouped in two sections: (1) the palladium-catalyzed cross-coupling reaction between alkoxydienylboronates and tetralone- or isochromanone-derived vinyl triflates; (2) the regio- and stereoselective cross coupling reaction with aryl derivatives in the presence of a palladium catalyst (Heck conditions).