Stereoselective Addition to N-Activated Pyridines James A. Bull,‡ James J. Mousseau, Guillaume Pelletier,† and Andre ́ B. Charette*,† †Department of Chemistry, Universite ́ de Montreál, P.O. Box 6128, Station Downtown, Montreál, Queb́ec, Canada H3C 3J7 ‡Department of Chemistry, Imperial College London, South Kensington, London SW7 2AZ, U.K. Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA

Synthesis of Pyridine and Dihydropyridine Derivatives by Regio- and Stereoselective Addition to N-Activated Pyridines

Publisher Summary This chapter discusses the chemistry of cationic dicyclopentadienyl group 4 metal–alkyl complexes. Neutral, d 0 group 4 metal alkyl complexes of general form Cp 2 M(R) 2 (R = H, hydrocarbyl) or Cp 2 M(R)(X) (X = anionic, two–electron donor) comprise the most extensively studied class of group 4 organometallics (I). For many years, it has been suspected that cationic d 0 metal–alkyl species Cp 2 M(R) + are involved in metallocene-based Ziegler–Natta olefin polymerization catalyst systems of the general type Cp 2 MX 2 /AIR n X 3 – n . Several key advances in the early 1980s generated renewed interest in the proposal that Cp 2 M(R) + ions are active species in the soluble catalyst systems. A simple but key point in the development of this chemistry was the realization that noncoordinating, nonreactive counterions, such as BPh 4 – are required for the isolation of stable salts. In 1976, Kaminsky reported the isolation of [(C 5 H 5 ) 2 Zr(CH 2 C(H)– (AIEt 2 ) 2 )][C 5 H 5 ] from the reaction of (C 5 H 5 ) 4 Zr and AIEt 3 . Cationic Cp 2 M(R)(L) + complexes exhibit a variety of interesting structural features, which result from the high Lewis acidity of the cationic d 0 metal centers. The tetrahydrofuran (THF) ligands in these complexes are labile and generally undergo rapid (nuclear magnetic resonance (NMR) time scale) exchange with free THF by dissociative or associative mechanisms at ambient temperature. Cationic, d 0 Cp 2 M(R)(L) + and base-free Cp 2 M(R) + complexes are easily prepared from readily available Cp 2 M(R) 2 compounds. There is strong evidence that Cp 2 M(R) + ions are the active species in Cp 2 MX 2 -based Ziegler–Natta olefin polymerization catalysts.

Chemistry of Cationic Dicyclopentadienyl Group 4 Metal-Alky I Complexes

Azines, which are six-membered aromatic compounds containing one or more nitrogen atoms, serve as ubiquitous structural cores of aromatic species with important applications in biological and materials sciences. Among a variety of synthetic approaches toward azines, C–H functionalization represents the most rapid and atom-economical transformation, and it is advantageous for the late-stage functionalization of azine-containing functional molecules. Since azines have several C–H bonds with different reactivities, the development of new reactions that allow for the functionalization of azines in a regioselective fashion has comprised a central issue. This review describes recent advances in the C–H functionalization of azines categorized as follows: (1) SNAr reactions, (2) radical reactions, (3) deprotonation/functionalization, and (4) metal-catalyzed reactions.

C–H Functionalization of Azines

Heterogeneous catalysis of the hydrodesulfurization of thiophenes in petroleum: an organometallic perspective of the mechanism

Synthesis of organotitanium complexes from alkenes and alkynes and their synthetic applications.

https://pure.rug.nl/ws/files/6803356/1982JOrganometChemKlei.PDF

E. Klei

Papers

Reaction of titanocene allyls

Reaction of titanocene alkyls with pyridines - a novel type of cyclometallation reaction

Preparation of (η5-C5H5)2Ti alkyl compounds and reactions with unsaturated substrates

On the nature and reactivity of Cp2TiCH3

Reaction of an alkenyltitanocene