Tetramethylguanidinium azide

Several 5,6-disubstituted-3-azido[l,2,4]triazine-l-oxides 1021 were prepared (77JHC1221) by treatment of 1020 with nitrous acid. 3-Azido[l, 2,4]-triazine-2-oxide 1023 was prepared by reacting the corresponding 3-bromo derivative 1022 with either tetramethylguanidinium azide in chloroform or sodium azide in aqueous acetone. These azido derivatives were proven to exist in the open-chain form by H- and l3C-NMR and 1R spectra (77JHC1221) (Scheme 191). 

Tetramethylguanidinium azide, an azide salt that is readily soluble in halogenated solvents, is a useful source of azide ions in the preparation of azides from reactive halides such as a-haloketones, a-haloamides, and glycosyl halides.74... 

Optically active a-azido acids as versatile a-amino acid synthons are obtained by diaste-reoselective halogenation of chiral auxiliary-based enols or enolatest followed by stereospecific azide displacement by A(A(A, A -tetramethylguanidinium azide or alternatively... 

The reaction of acid chlorides with tetramethylguanidinium azide also proceeds under very mild con-ditions. Using this technique even r-alkyl azidoformates may be prepared (Scheme 38). Quantitative yields of acyl azides (in solution) are reported for the interaction of acid chlorides in toluene with HNs/pyridine at 0 °C. Even sterically hindered educts are smoothly converted into acyl azides. If tetraalicylammonium azides are used, the use of hazardous hydrazoic acid is avoided. ... 

In place of sodium azide, which has low solubility in common organic media, use of a mixture of hy-drazoic acid and pyridine, tetrabutylammonium azide or tetramethylguanidinium azide has been recommended. One of the most useful and safe alternatives is trimethylsilyl azide (50), which reacts with various acyl chlorides or anhydrides to give isocyanates directly, under thermal conditions (Scheme... 

Preparation. Sakai and Anselme1 recommend that the reagent be prepared by the reaction of /-butyl chloroformate and tetramethylguanidinium azide (2,403-404) ... 

The most general route to 5-substituted tetrazoles involves condensation of the appropriate nitrile with azide ion. The variation in the yields of tetrazoles obtained in different solvent systems has been summarized recently for much of the earlier work.3 Although inorganic azides are usually used, 1,1,3,3-tetramethylguanidinium azide has proved to be a particularly useful source of azide ion, which gives high yields of... 

Nosyloxy malate 194, prepared from 2 in 80% yield (NsCl, EtsN, DMAP, CH2CI2, 0 °C), undergoes clean inversion when treated with 1,1,3,3-tetramethylguanidinium azide to give dimethyl (i )-2-azidosuccinate (195) with > 95% ee [69]. Mild reduction of the azide group with triphenylphosphine affords dimethyl (7 )-aspartate (196) with no observable racemization. 

In 1966 tetramethylguanidinium azide (TMGA) (28) was prepared as an hydroscopic colourless, but stable, crystal by treatment of TMG (1) with hydrogen azide and was introduced by Papa [104] as a reactive azidation reagent (Table 4.17). 

Papa, A.J. (1966) Synthesis and azidolysis of 2-chlorotetramethylguanidine. Synthetic utility of hexa- and tetramethylguanidinium azide. The Journal of Organic Chemistry, 31, 1426-1430. 

Li, C., Shih, T.-L., Jeong, J.U. era/. (1994) The use of tetramethylguanidinium azide in non-halogenated solvents avoids potential explosion hazards. Tetrahedron Letters, 35, 2645-2646. 

Blaszczyk, R. (2008) Tetramethylguanidinium azide (TMGA)-a versatile azidation agent. Synlett, 299-300. 

Palacios, ., Aparicio,D., delosSantos, J.M. era/. (1995) Onepot synthesis of P-functionalized vinyl azides through addition of tetramethylguanidinium azide to acetylenic and allenic compounds. Organic Preparations and Procedures International, 27, 171-178. 

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