PdII -Catalyzed Cascade Synthesis of Chromane Derivatives Initiated by cis-Chloropalladation or trans-Acetoxypalladation.

A highly regio- and stereoselective PdII -catalyzed cascade synthesis of biologically relevant chromane derivatives from easily available enynes was developed under operationally simple conditions. The cascade reaction consists of nucleopalladation of alkynes, insertion of the alkene and protonation. When CuCl2 was employed as nucleophile, a cis-chloropalladation initiates the cascade. Whereas in the case of AcOH, a trans-acetoxypalladation takes place.