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Synthesis of Methyl Groups catalysed by Vitamin B12r in vitro

Naturevolume 214page492 (1967) | Download Citation



THE use of Raney metal catalysts for the reductive methylation of amines with formaldehyde and hydrogen is well known1. We wish to report that this reaction is also catalysed by vitamin B12r in vitro, and thus is potentially of biochemical importance. For example, a 1 : 1 mixture of aniline and formaldehyde in methanol and water absorbs hydrogen at room temperature and 1 atm. of pressure if a solution of vitamin B12r is added. N-methylaniline is formed in significant yield (1). Bis-dimethylglyoximato cobalt (II) complexes such as Co(D2H2)·2H2O (‘Diaquocobaloxime (II)’)2 (D = dianion of dimethylglyoxime) which may be regarded as simple models of vitamin B12r were similarly found to be cataly-tically active. Aniline could also be substituted by N-methylaniline which was converted to N,N-dimethylaniline under analogous conditions. In order to isolate or detect intermediates of this reaction, the reductive alkylation of aniline was also carried out using stoichio-metric amounts of the react ants. When 0.4 moles of aniline and 0.25 moles of formaldehyde (in 40 per cent aqueous solution) were added to a suspension of 0.20 moles of Co(D2H2)·2H2O in 1 l. of methanol under 1 atm. of hydrogen, 0.1 mole of hydrogen was rapidly absorbed on stirring and the cobaloxime dissolved completely. On addition of 1 l. of water a crystalline complex precipitated in a yield of 94 per cent, which was dissolved in methanol and reprecipitated by adding water. After drying at 0.1 mm of mercury 25° C it analysed for C21H29N604CoH2O, corresponding to

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  1. 1

    Mignonac, G., C. R. Acad. Sci., Paris, 172, 223 (1921).

  2. 2

    Schrauzer, G. N., and Windgassen, R. J., Chem. Ber., 99, 602 (1966).

  3. 3

    Schrauzer, G. N., and Windgassen, R. J., J. Amer. Chem. Soc., 88, 3738 (1966).

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    Present address: Department of Chemistry, University of California, San Diego, Revelle College, La Jolla, California, 92038


  1. Shell Development Company, Emeryville, California

    •  & R. J. WINDGASSEN


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