Cobalt-catalyzed one-step synthesis of annulated pyridines

US4328343A · kind A · utility

Assignee

• The United States of America, as represented by the Department of Health and Human Services · US

Inventors

• K. Peter C. Vollhardt · Oakland, US
• Alaric Naiman · Cambridge, US

Key dates

• Filing date: Jul 5, 1979
• Grant date: May 4, 1982
• Expiry date: Jul 5, 1999

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C07D495/04
• WIPO field: Organic fine chemistry
• WIPO sector: Chemistry

Abstract

A method of synthesizing fused ring pyridines (annulated) by co-oligomerization of .alpha.,.omega.-diynes with about molar equivalents of nitriles using a Co.sup.+1 catalyst preferably cyclopentadienyl cobalt dicarbonyl. Additionally, new compounds of tricyclic quinolizine-4-ones were produced where excess cyanoacetic ester starting materials were utilized (about 2:1 equivalent nitriles:diyne). The results with the catalyst employed indicated a stepwise mechanism in which cobalt(I) catalyst first forms a metallocycle intermediate derived from the bisacetylene. This cobalt(III) intermediate reacts preferentially with nitriles to give the product annulated pyridines in good yield. Generally, preferred conditions indicated roughly molar equivalents of reactants with no substantial excess of either reactant for the bicyclic compounds. Preferred conditions include a moderate temperature (solvent reflux temperature) and a preferred solvent such as BTX-type solvent (xylene) or an alkane (N-octane) under an inert blanket (nitrogen) for a multi-day period.