New metal-catalyzed synthesis of quinoline and chromene skeletons

Alkoxy-functionalized butadienylboronic esters have been synthesized starting from alpha,beta-unsaturated acetals and cross-coupled with both N-protected and N-unprotected 2-bromoand 2-iodoaniline, and with 2-iodophenol. In particular, N-tosyl-protected dienylanilines can be transformed under mild conditions into quinolines and quinolinones, in the presence of a Pd-II catalyst. Moreover, the cross-coupling reaction between butadienylboronic esters and iodophenol directly affords chromenes that can be successively transformed into chromenones. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)