Tris(dimethylamino)methane explained

Tris(dimethylamino)methane (TDAM) is the simplest representative of the tris(dialkylamino)methanes of the general formula (R2N)3CH in which three of the four of methane's hydrogen atoms are replaced by dimethylamino groups (−N(CH3)2).[1] Tris(dimethylamino)methane can be regarded as both an amine and an orthoamide.

Tris(dimethylamino)methane is a strong base and can be used as a formylation agent, as aminomethylenation reagent and as a source for the basic bis(dimethylamino)carbene of the formula (R2N)2C:.[2]

Preparation

Tris(dimethylamino)methane is formed in the reaction of N,N,N′,N′-Tetramethylformamidinium chloride (TMF-Cl)[3] [4] or bis(dimethylamino)acetonitrile[5] with lithium dimethylamide or sodium dimethylamide with yields between 55 and 84%.[2]

From dimethylamine and trimethoxyborane sodium dimethylamide is formed in situ in the presence of sodium hydride which reacts with N,N,N,N-tetramethylformamidinium chloride in 84% yield to tris(dimethylamino)methane and with bis(dimethylamino)acetonitrile in 77% yield.[6]

The reaction of the dimethylformamide (DMF) dimethylacetal, HC(OCH3)2N(CH3)2, (from the DMF–dimethyl sulfate complex and sodium methoxide[7]) with dimethylamine in the presence of the acidic catalyst 2,4,6-tri-tert-butylphenol (which is largely stable to the alkylating agent) produces tris(dimethylamino)methane.[8]

Tris(dimethylamino)methane is formed in good yield (83%) in the reaction of DMF with tetrakis(dimethylamino)titanium(IV).[9]

N,N,N,N,N″,N″-Hexamethylguanidinium chloride (readily obtainable by dimethylamine and N,N,N,N-tetramethylchloroformamidinium chloride derived from tetramethylurea and phosgene[10]) forms tris(dimethylamino)methane in 53% yield under the exposure of the reducing agent sodium bis(2-methoxyethoxy)aluminium hydride (Red-Al).[11]

Sodium hydride and trimethyl borate reduce N,N,N,N,N″,N″-hexamethylguanidinium chloride in 80% yield to tris(dimethylamino)methane.[6]

Properties

Tris(dimethylamino)methane is a clear, colorless or pale yellow liquid with a strong ammoniacal odor. The compound is freely miscible with many non-polar aprotic and water-free solvents. However, when heated tris(dimethylamino)methane reacts with protic solvents (such as water or alcohols) but also with weak CH-acidic substances, such as acetone or acetonitrile.[2]

Upon heating to 150–190 °C decomposition occurs with the formation of tetrakis(dimethylamino)ethene,[12] a strong electron donor.[13]

Applications

Tris(dimethylamino)methane dissociates into N,N,N,N-tetramethylformamidinium cations and dimethylamide anions, which abstract protons from CH- and NH-acidic compounds. The anions thus formed add to the formamidinium cations which in turn eliminate dimethylamine and react to form dimethylaminomethylene compounds (= CH−N(CH3)2) or amidines by aminomethyleneation.[1]

Reaction to form a methyl α-cyano-β-dimethylaminoacrylate:

Reaction to form N,N-dimethyl-N-p-nitrophenylformamidine:

Aminomethylenation provides intermediates for the synthesis of heterocycles such as pyrimidines, pyrazoles, 1,4-dihydropyridines and indoles.

N,N,N,N-Tetramethylselenourea is accessible by the extended heating of tris(dimethylamino)methane with selenium in xylene, bis(dimethylamino)carbene is suggested as an intermediate.[14]

Related reagent

Notes and References

  1. H.. Bredereck. F.. Effenberger. T.. Brendle. Angewandte Chemie. Synthese und Reaktionen von Trisdimethylaminomethan. Synthesis and reaction of tris(dimethylamino)methane. 78. 2. 1966. 147–148. German. 10.1002/ange.19660780212. 1966AngCh..78..147B .
  2. Encyclopedia: W.. Kantlehner. Encyclopedia of Reagents for Organic Synthesis. Tris(dimethylamino)methane. 2001. 10.1002/047084289X.rt403. 0-471-93623-5.
  3. DE. 1217391. Verfahren zur Herstellung von Tris-dimethylaminomethan (Process for the production of tris(dimethylamino)methane). 1966-12-08. 1964-09-29. Bredereck, H.. Effenberger, F.. Brendle, T. . Bredereck, H..
  4. Chemische Berichte. Orthoamide. V. Synthese von Tris-dialkylamino-methanen. Orthoamides. V. Synthesis of tris(dimethylamino)methane. H.. Bredereck. F.. Effenberger. T.. Brendle. H.. Muffler. 101. 5. 1968. 1885–1888. German. 10.1002/cber.19681010541.
  5. W.. Kantlehner. T.. Maier. P.. Speh. Synthesis. Tris(dialkylamino)methane und Tetraalkylformamidinium-Thiocyanate aus Bis(dialkylamino)acetonitrilen. Tris(dialkylamino)methanes and tetraalkylformamidinium thiocyanates from bis(dialkylamino)acetonitriles. 1979. 5. 1979. 342–343. German. 10.1055/s-1979-28671. 97378246 .
  6. Orthoamide. LII. Beiträge zur Synthese von Orthocarbonsäureamiden. Journal für praktische Chemie. Orthoamides. LII. Articles on the synthesis of carboxylic acid orthoamides. 342. 3. 2000. 256–268. W.. Kantlehner. R.. Stieglitz. M.. Hauber. E.. Haug. C.. Regele. German. 10.1002/(SICI)1521-3897(200003)342:3<256::AID-PRAC256>3.0.CO;2-G.
  7. H.. Bredereck. F.. Effenberger. G.. Simchen. Angewandte Chemie. Reaktionsfähige Säureamid-Dimethylsulfat-Komplexe. Reactive acid amide–dimethyl sulfate complexes. 73. 14. 1961. 493. German. 10.1002/ange.19610731407. 1961AngCh..73..493B .
  8. DE. 2214497. Verfahren zur Herstellung eines aminosubstituierten Methanderivates (Process for the manufacture of an amino-substituted methane derivative). 1972-10-05. 1972-03-24. Leimgruber, W.. Wick, A. E.. F. Hoffmann-La Roche & Co. AG.
  9. H.. Weingarten. W. A.. White. Journal of the American Chemical Society. A novel amination reaction of carboxylic acid derivatives with tetrakis(dimethylamino)titanium. 1966. 88. 4. 850. 10.1021/ja00956a049.
  10. W.. Kantlehner. E.. Haug. W. W.. Mergen. P.. Speh. T.. Maier. J. J.. Kapassakalidis. H. J.. Bräuner. H.. Hagen. Synthesis. Ein Herstellungsverfahren für N,N,N,N,N″,N″-Hexaalkylguanidinium-chloride. A manufacturing process for N,N,N,N,N″,N″-hexaalkylguanidinium chlorides. 1983. 11. 1983. 904–905. German. 10.1055/s-1983-30558. 93420838 .
  11. W.. Kantlehner. P.. Speh. H. J.. Bräuner. Synthesis. Eine einfache Synthese für Tris(dialkylamino)methane. A simple synthesis for tris(dialkylamino)methanes. German. 1983. 11. 1983. 905–906. 10.1055/s-1983-30559. 101466032 .
  12. H.. Bredereck. F.. Effenberger. H. J.. Bredereck. Angewandte Chemie. Eine neue Synthese von Tetra(dimethylamino)äthylen. A new synthesis of tetra(dimethylamino)ethylene. 78. 21. 1966. 984. German. 10.1002/ange.19660782113. 1966AngCh..78..984B .
  13. N.. Wiberg. J. W.. Buchler. Angewandte Chemie. Tetrakis(dimethylamino)äthylen: Ein starker Elektronendonator. Tetrakis(dimethylamino)ethylene: A strong electron donor. German. 10.1002/ange.19620741410. 74. 14. 1962. 490–491. 1962AngCh..74..490W .
  14. W.. Kantlehner. M.. Hauber. M.. Vettel. Journal für praktische Chemie. 10.1002/prac.19963380180. Orthoamide. IL. Umsetzungen von Orthoamid-Derivaten mit Schwefel und Selen, Synthesen von 1,3-Thiazol- und 1,3-Selenazolderivaten. Orthoamides. XLIX. Reactions of orthoamide derivatives with sulfur and selenium, syntheses of 1,3-thiazole and 1,3-selenazole derivatives. 338. 1. 1996. 403–413. German.

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