Azides, trimethylsilyl azide synthesis

The cyclocondensation of trimethylsilyl azide with a bis(sulfenyl chloride) is an efficient synthesis of dithiazolium cations (Section 11.3.5) (Eq. 2.15). ... 

The primary route to 1,3,2-dithiazolium salts involves the cyclocondensation of l,2-bis(sulfenyl chlorides) with trimethylsilyl azide, which is illustrated for benzo-fused derivatives in Eq. 11.11. ° This method can be extended to the synthesis of bis( 1,3,2-dithiazolylium) salts. 

Deprotection of N-2 by ozonolysis furnishes triazoles 1225 (Scheme 202) <2003JA7786>. Finding that 1,3-dipolar cycloaddition of alkynes 1222 to trimethylsilyl azide, carried out in DMF/MeOH in the presence of Cul as a catalyst, leads directly to products 1225 with much higher yields provides a significant progress to the synthesis of N-unsubstituted 1,2,3-triazoles <2004EJO3789>. 

A simple procedure for the synthesis of 4,5-disubstituted 1,2,3-triazoles 1247 involves stirring a mixture of nitroethene 1245 with trimethylsilyl azide and tetrabutylammonium fluoride at 30 °C for 3h. No solvent is needed. Triazoline 1246, which forms in the first step of the reaction, eliminates nitrous acid, and the trimethylsilyl group is cleaved off by the fluoride anion to afford triazole 1247. Various aryl and heteroaryl substituents R are used providing triazoles 1247 in 70-90% yield (Scheme 207) <2005JOC6526>. 

N, C -Coupling reaction of BENA with trimethylsilyl azide is the key step of a very convenient and versatile procedure for the synthesis of otherwise difficultly accessible a-azido oximes (524, 525) (Scheme 3.248). 

A research team at Rhone-Poulenc reported a four-component procedure for the synthesis of variously substituted heteroaromatic tetrazolo[l,5-zz]pyrazines <1998TL2735>. Thus, aldehydes, primary amines, trimethylsilyl azide, and methyl /3-(iV,iV-dimethylamino)-a-isocyanoacrylates 117 were reacted in a methanolic solution at room temperature to yield the product 119 in high yields. The reaction was rationalized to proceed via the formation of intermediate 118. The procedure proved to be efficient for combinatorial chemical applications. 

Trimethylsilyl (TMS) derivatives in organic synthesis, 22 695-696 as silylating agents, 22 694 Trimethylsilyl azide, as silylating agent, 22 695-696... 

Gilardi and co-workers reported a synthesis of 4-(trimethylsilyl)-5-nitro-1,2,3-triazole (136) via a cycloaddition between l-nitro-2-(trimethylsilyl)acetylene (134) and trimethylsilyl azide (135). This may provide a route to 4,5-dinitro-l,2,3-triazole via nitrodesilylation or lead to the synthesis of 4-amino-5-nitro-l,2,3-triazole, an isomer of ANTA. 

Goodman and Chorev 75 found that the required a-aminoacyl azides 14 are best prepared by reaction of the mixed anhydride of the amino acid with sodium azide. This method led to slightly better yields than the nitrosylation of TV-formylaminoacyl hydrazide. Curtius rearrangement of the a-aminoacyl azide 14 yielded the isocyanate 16, which was subsequently trapped as 17 or 18 as shown in Scheme 2. Comparable yields were obtained by nitrosylation with tert-butyl nitrite. 76 Other methods of acyl azide formation have rarely been employed for PMRI-peptide synthesis. Only Fincham et al. 11 reported the use of trimethylsilyl azide to synthesize an acyl azide en route to a PMRI-peptide. 

Stable triazolines are obtained from aryl azides and V-alkyl and N-aryl maleimides (Scheme 81 )307-309a the reaction succeeds with silyl azides310 and is utilized in the synthesis of polymers from bisazides and bismaleimides.311 312 Unlike maleimides, maleic anhydrides do not yield stable triazolines with trimethylsilyl azide the reaction products are oxazinediones (Section IV,A).310,313,314... 

The synthesis of 1,3,2-dithiazolidines from bis(sulfenylchlorides) and amines has been developed in the 1990s and 2000s (Equations 12 and 14). Trimethylsilyl azide confirmed its important role in the preparation of fused mono- and bis-l,3,2-dithiazolium cations (Equation 18). Oakley and co-workers showed that o-dimercapto derivatives can be used in the synthesis of these compounds if treated with trithiazyl trichloride (Equation 19). Synthesis of iV-substituted 1,3,2-benzodithazole tetraoxide has been successfully carried out from benzene-bis(sulfonylchloride) and aliphatic amines (Equation 15). An important feature in this reaction is the preparation of chiral derivatives from optically pure amines (Equations 16 and 17). 

A similar procedure was applied to the synthesis of isomeric 1,5-dialkyltetrazoles analogs of the most important naturally occurring fatty acids, from methyl 9(10)-oxooctadecanoate, sodium azide, and titanium(rv) chloride (MeCN, reflux, 5 h) <2003EJ0885>. A convenient synthesis of tetrazoles (e.g., 524) by reaction of trimethylsilyl azide and ZnBr2 with a-dialkylated (3-ketoesters is based on the same approach (Equation 99 Table 32) <2003TL3179>. 

A new synthesis of purines is illustrated by the reaction of l,3-dimethyl-6-aminouracil with MiV-dimethyldichloromethyleneiminium chloride (phosgeneiminium chloride), trimethylsilyl azide and arylamines in dry chloroform, followed by treatment with 20% aqueous potassium hydrogen carbonate. The reaction probably proceeds via a 4-amino-5-(chloroformamidin-l -yl)uracil (Scheme 10) [94JHC1185],... 

A similar approach to the hydrolytic methodology uses a chromium-salen complex to open an epoxide with trimethylsilyl azide, as illustrated by the synthesis of the antihypertensive agent, (S)-propranolol (10) (Scheme 9.15).118,119... 

The p-amino-a-hydroxy esters have been converted to diamino acids [88, 89] and related compounds like the nitrogen-substituted azetidinone shown in Scheme 13, a key structure in the synthesis of the commercially available antibiotic loracarbef [90] by substitution of the alcohol moiety with an azide. Several approaches have been used to achieve this transformation. Mesylation of the alcohol followed by substitution with sodium or trimethylsilyl azide provided cis-diamino acids [88,89]. trans-Diamino acids were obtained by ring opening of the aziridine [88] or by inversion of the alcohol bearing carbon followed by substitution under Mitsunobo conditions [90]. 

We reported that the palladium-catalyzed three-component coupling reaction of the activated alkynes 41, allyl methyl carbonate 5b, and trimethylsilyl azide 42 gave the 2-allyl-1,2,3-triazoles 43. The reaction proceeds via the [3 + 2] cycloaddition of tt-allylpalladium azide 44 to the alkynes 41, followed by the formation of (-allyl)(r]5-triazoyl)-palladium 45 (Scheme 16) [51]. However, this method was limited only for activated alkynes. Synthesis of the triazoles 47 from the nonactivated terminal alkynes 46 was achieved by the three-... 

The selective synthesis of the 2-allyltetrazoles 55 by the three-component coupling reaction of the cyano compounds 54, allyl methyl carbonate 5b, and trimethylsilyl azide 42 was accomplished in the presence of Pd2(dba)3.CHCl3 and P(2-furyl)3 (Scheme 19) [55,56]. Most probably, the formation of (r)3-allyl)( ]5-tetrazoyl)-palladium complex 56 took place through [3 + 2] dipolar cycloaddition of 7r-allylpalladium azide 44 with the nitrile 54. The complex 56 thus formed would undergo reductive elimination to form the products 55. 

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