Trimethylsilylazide, reaction with

In studying the reactivity of iV-fluoropyridinium fluoride 127 obtained from pyridine 126 by treatment with fluorine gas in chloroform at low temperature (Scheme 30), Kiselyov studied reactions with isocyanides in the presence of trimethylsilylazide <2005TL4851>. A mixture of products was obtained in which, besides tetrazolylpyr-idine 128 and a nicotinamide derivative 129 also tetrazolo[l,5-tf]pyridine 1 was obtained in very poor yield (5-10%). 

Treatment with azido compounds, such as azide ion [Eq. (65)], halidoazide [reaction (66)], or trimethylsilylazide [reaction (67)], which is the most common nitride-forming pathway. 

Addition reactions of low coordinate phosphorus compounds have proved to be an interesting route to novel acyclic phosphazenes. Phosphino carbenes, R2PCSiMej, exhibit typical multiple bond behavior in 2+3 cycloaddition reactions with trimethylsilylazide. The cycloadduct easily rearranges to the diazo derivatives R2P(=NSiMe3) C (=N2) SiMej. The addition of the... 

Recent advances in the Staudinger reaction of tertiary phosphines with azido compounds have been reviewed.The reaction of the alkynylphosphine (88) with phenylazide yields the unstable intermediate (89), which in the presence of protic substances undergoes nucleophilic addition to the triple bond. The reactivity of the nitrogen-silicon bond of the phosphinimine derived from triphenylphosphine and trimethylsilylazide has been exploited in reactions with chloroformyl reagents to generate new functionalised phosphinimines, e.g., (90). ... 

Reactions with lead tetraacetate/trimethylsilylazide (CHfiOO) Pbl(CH ) SiN ... 

The reaction of an azide[185,186] or a trimethylsilylazide(I87] followed by the treatment with Ph3P is another preparative method for the primary allylic amine 307. 

An interesting [1,3]-Si shift from nitrogen to nitrogen has been observed in the Staudinger imination reaction of AT-ferf-butyl-iV-trimethylsilyl-P,P-di-methyl phosphinous amide 32 with trimethylsilylazide [137]. The steric bulk provided by the tert-hutjl group seems to determine the direction of the silyl shift (Scheme 32). 

Addition of thiophosgene to the reaction mixture of ImCSIm and trimethylsilylazide causes the yield to become quantitative.11301,11323 In the conversion with trimethylsilyl azide the required ImCSIm could also be made in situ from trimethylsilylimidazole and thiophosgene, giving the thiatriazoles in 70—80% yield.11321... 

An interesting palladium-catalyzed allene/azide incorporation and intramolecular 1,3-dipolar cycloaddition cascade to tetrazolo[5,l-tf]isoquinoline has been published by Grigg et al. <2005TL5899>. In the first step of the events, 3-bromo-6-iodobenzonitrile 105 was reacted with the allene/trimethylsilylazide system in the presence of palladium(O) catalyst to yield a coupling product 106 which under the reaction conditions applied (DMF, 70 °C for 24 h) gave 107. 

Umkehrer et al. developed the synthesis of tetrazolopiperazine building blocks 178 via Ugi five-center-four-component reaction (U-5C-4CR) of primary amines 179, aldehydes 180, trimethylsilylazide 181, and 2-isocyanoethyltosylate 182 [54]. The in situ generated secondary amine finally gets alkylated by the toluenesulfo-nate, leading to the expected fused tetrazoles 178 (Scheme 31). The primary amines and the aldehydes can be varied broadly, which allows to produce products with two potential diversity points. 

A library of piperazine containing fused azepine-tetrazoles 183 was built by Nixey et al. via Ugi reaction in the solution phase [55]. This library comprises an example of a building block introduced piperazine (Scheme 32). The reaction of A-Boc-a-amino aldehyde 184, methyl isocyanoacetate 185, substituted piperazines 186, and trimethylsilylazide 181 in methanol, followed by acid treatment, proton scavenging, and reflux affords bicyciic azepine-tetrazoles 183. This efficient protocol with three diversity points can be used to generate arrays of biologically... 

In the case of activated isothiocyanates such as phenylsulfonyl and pyridyl isothiocyanates the enhanced reactivity of the isothiocyanate again only results in reaction at the C=S bond rather than the N=C bond which would have given rise to tetrazoles <77CCC1557>. Floch et al. have found that replacement of hydrazoic acid with trimethylsilylazide in 80% aqueous ethanol at 20 °C leads to a much faster reaction (2 days vs. 20 days) and good yields (60-80%) <77CCC2945>. 

Palladium-mediated cydization based on the reactivity of o-alkynyl or alkenyl-phenyl isonitriles have been developed [105]. On the basis of their earlier studies on the three-component synthesis of allyl aryl cyanamides [106], Yamamoto and co-workers reported a palladium-catalyzed three-component coupling reaction of 2-alkynylisocyanobenzenes 122 with allyl methyl carbonate and trimethylsilylazide leading to N-cyanoindoles 125 [107]. One of the key steps of the proposed mechanism is the formation of 7i-allylpalladium carbodiimide 123 and its isomerization to rc-allylpalladium cyanamide complex 124 (Scheme 8.50). 

Reaction between trimethylsilyldiazomethane and trimethylsilylketene produces the disilylcyclopropanone. This was reacted with trimethylsilylazide to form the corresponding azetidinone in high yields after heating.122... 

The dehydrochlorination of 4-(l-chloroalkyl)azetidin-2-ones with dimethyl sulfoxide offers a new route to 3,4-zfr-4-isopropenylazetidin-2-ones 369 (Equation 138) <2005JOC8717>. The reaction of the latter compounds with bromine (Scheme 53) or with a mixture of iV-bromosuccinimide and trimethylsilylazide (Equation 139) led to an electrophile-induced ring expansion toward pyrrolidin-2-ones 370 and 371. 

Only one nitrido Ww complex has been documented. This was prepared by the action of Me3SiN3 followed by oxidation on dinitrogen W° complex 83 (Eq. (31)) [36]. It has been proposed that the reaction of 83 with trimethylsilylazide affords a Wn complex bearing two N3-ligands a subsequent two-electron oxidation of the metal center then affords nitrido tungsten complex 84. 

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