Cobalt-catalyzed one-step synthesis of annulated pyridines

Details Cobalt-catalyzed one-step synthesis of annulated pyridines Cobalt-catalyzed one-step synthesis of annulated pyridines

1979-07-05

1982-05-04

Daus, Donald G.

Organic compounds -- part of the class 532-570 series

Organic compounds

Heterocyclic carbon compounds containing a hetero ring...

546 94, 546139, 546144, 546147, C07D21714, C07D22104, C07D45504

Patent

active

043283438

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.

REFERENCES:
Hackh's Chem. Dictionary, p. 62, (1972), McGraw-Hill Co., N.Y.
S. Archer, J. Org. Chem. 16, 430-1, (1951).
R. Hilliard et al., Chem. Abstracts 84:30726t, (1976), Transition Metal Catalyzed Acetylene Cyclizations.
T. Cairns et al., J. Amer. Chem. Soc., 74:3989-3992, (1952), Synthesis of Pyrimidines and Pyridines from Acetylene and Nitriles.

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