ChemInform Abstract: The Cobalt Way to Vitamin B6. Regioselective Construction of the Tetrasubstituted Pyridine Nucleus by Cobalt‐catalyzed Alkyne‐Nitrile Cooligomerizations.

Abstract

Cocyclization of diyne (I) (prepared via silylation of bis‐2‐propynyl ether) with MeCN (II) in the presence of Co complex (III) yields the pyridine derivative (IV) which on purification affords (V).

Simple Synthesis of Pyrethroid Metabolites

“…Hydroxylation of aromatic compounds in this way is a convenient synthesis procedure using mild conditions. It has been adopted for chemicals with aromatic structures such as estradiol (Santaniello and Ferraboshi, 1981;Kirk and Slade, 1982;Santaniello et al, 1983), estrone (Santaniello et al, 1983;Kirk and Slade, 1983;Berrier et al, 1984), vitamin Be (Parnell and Vollhardt, 1985), and quinol acetate derivatives (Kara et al, 1980;Begley et al, 1988).…”

Origins of Regio- and Chemoselectivity in Iron-PDAI-Catalyzed [2+2+2] Cycloaddition Syntheses of 4,6-Disubstituted 2-Aminopyridines

“…Metal-catalyzed [2+2+2] cycloaddition reactions are a valuable tool in synthetic organic chemistry that allow access to substituted carbo- and heterocycles in a one-step reaction. The high atom and step economy and the broad functional group tolerance of such reactions are highly appealing for synthetic chemists. − Literature reports illustrate myriad efficient catalytic species (e.g., Rh, − Ru, − Ir, − Co, − Ni, − Nb, Au, Cu, Fe − ) and coupling partners (e.g., olefins, nitriles, isocyanates, cyanamides, aldehydes, ketones, carbon dioxide, imines, carbodiimides), which highlight the great potential of these cycloaddition reactions. − Furthermore, their broad applicability is demonstrated by the diversity of synthetic strategies that incorporate these reactions as a key step in the synthesis of natural products, − polymers, , electroluminescent materials, − and other aromatic building blocks ,,…”