The Boehringer-Ingelheim phosphinoimidazoline (BIPI) ligands were applied to the formation of chiral quaternary centers in the asymmetric Heck reaction. Several different substrates were examined in detail, using more than 70 members of this new ligand class. Hammett relationships were determined through systematic variation of the ligand electronics. All substrates showed essentially the same Hammett behavior, where enantioselectivity increased as the ligands were made more electron-deficient. Ligand optimization has led to catalysts which give the highest enantioselectivities reported to date for these difficult systems.

No abstract

The reaction of various α,β‐unsaturated acetals with two equivalents of the Schlosser reagent LIC‐KOR [equimolar mixture of BuLi (LIC), and tBuOK (KOR)] gives 1‐metalated (1E)‐1‐alkoxy‐1,3‐dienes. These products can be transformed into trienic derivatives that are apt to participate in intramolecular Diels–Alder (IMDA) cycloaddition reactions, and can also be transformed into bifunctional (γ‐halo‐α‐carbonyl) reagents. Moreover, the metalated dienes can be readily functionalized with suitable electrophiles to afford products that have been found to be useful reagents for the Stille and Suzuki cross‐coupling reactions or arylated according to the conditions of the Heck process. Other significant syntheses of dienic and polyenic structures are reported along with some of their applications in organic synthesis. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

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).

Alkoxydienyl boronates 1a and 1b and alkoxystyryl boronate 2 have been used in various copper mediated cross‐coupling reactions with azoles. A variety of N‐alkoxydienyl‐ and N‐styrylazoles have been synthesized under mild conditions. The process utilizes Cu(OAc)2 in the presence of CsF in CH2Cl2 at room temperature. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)