New Metal‐Catalyzed Synthesis of Quinoline and Chromene Skeletons

Alkoxy‐functionalized butadienylboronic esters have been synthesized starting from α,β‐unsaturated acetals and cross‐coupled with both N ‐protected and N ‐unprotected 2‐bromo‐ and 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. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)