Triisopropylbenzenesulfonyl azide

Preparative Methods readily prepared by treatment of the commercially available triisopropylbenzenesulfonyl chloride (trisyl chloride) with sodium azide.  

The Australian National University, Canberra, Australian Capital Territory, Australia 

General Considerations. The reactions of arylsulfonyl azides with enolates have been reported to give a range of products, depending on the fragmentation of the initial adduct. This may differ according to the nature of the enolate, the particular sulfonyl azide, and the quenching procedure. Net diazo transfer is usually observed for stabilized enolates, while azide transfer is more common with more reactive enolates. 

Diazo Transfer to Ketones. Triisopropylbenzenesulfonyl azide has been used for the direct transfer of the diazo group to ketone enolates under phase transfer conditions to furnish a-diazo ketones (eqs l-4).  

The method may be used as a more direct alternative to the stepwise procedure of hydroxymethylenation, followed by treatment with p-toluenesulfonyl azide and triethylamine, but its greatest value lies with the reactions of sterically hindered substrates 

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Triisopropylbenzenesulfonyl azide (trisyl azide), ArSCKN, (1), m. p. 41-43°. Preparation from trisyl chloride and NaN, (80% yield).1... 

Although some reactions of electrophilic animation of phosphorus-stabilized anions had already been reported in the literature [5a,d], the first example of such a stereoselective reaction opening access to optically active a-amino phosphonic acids was described in 1992 by Denmark and co-workers [45] and by Jommi and co-workers [46]. Both of these groups used chiral amino alcohols as auxiliaries for diastereo-selective induction in the animating process. Denmark and co-workers chose trisyl azide (2,4,6-triisopropylbenzenesulfonyl azide) as equivalent of NHJ , whereas Jommi and co-workers performed the reaction with DTBAD. 

K. enolate with KHMDS (1.1 equiv) in THF at — 78, C (30min) the Li enolate is similarly prepared with LDA. b TrisylN, = 2,4,6-triisopropylbenzenesulfonyl azide PNBSA = 4-nitroben-zenesulfonyl azide. c Recovered starting material. a Inverse addition of 1 to trisyl azide. e 2 equiv are used. 

Failure to use 2,4,6-Triisopropylbenzenesulfonyl Azide results in substantial diazo imide formation. However, optimization for the formation of the a-diazo imide compounds can be achieved with NaHMDS and p-nitrobenzenesulfonyl azide, followed by a neutral quench (eq 27). These diazo compounds, however, have failed to demonstrate utility in asymmetric carbenoid chemistry. ... 

The stereoselective total synthesis of tt)-campherenone was accomplished by T. Uyehara and co-workers based on a photochemical Wolff rearrangement. The bicyclic ketone was treated with 2,4,6-triisopropylbenzenesulfonyl azide (trisyl azide) under homogeneous basic conditions and the a-diazo ketone was obtained in excellent yield. The photochemical rearrangement of the diazo ketone was conducted in a THF-water mixture using a high-pressure 100 W mercury lamp. The ring-contracted acid was isolated as a 4 1 mixture of endo and exo products. 

A direct diazo transfer reaction to bicyclo[3.2.1]oct-6-en-2-one20 (50) is accomplished with 2,4,6-triisopropylbenzenesulfonyl azide and f-BuOK at -78 °C in THF. 

By contrast, less acidic substrates such as simple ketones cannot be converted directly to a-diazoketones by tosyl azide. However, when 2,4,6-triisopropylbenzenesulfonyl azide (182) was substituted for tosyl azide, the phase-transfer method gave good results with a... 

Nitrogen is introduced into the 3-position of the azetidinone ring as an azido group by reaction of TBS-protected 43 with 2,4,6-triisopropylbenzenesulfonyl azide. The reaction is stereospecific, yielding the desired trans 3S,4R relationship. 

The direct diazo transfer from sulfonyl azides to methyl ketones is usually not a practicable process, with the exception of the a-diazotization of ketones with 2,4,6-triisopropylbenzenesulfonyl azide under phase-transfer conditions. However, diazomethyl ketones amenable to the Arndt-Eistert reaction can be easily prepared in two steps by a formylation-deformylation diazo-transfer sequence (Regitz procedure ). A related practical method advantageously applies the detrifluoroacetylation of a-trifluoroacetyl ketones tScheme 3 a). The preparation of 2-diazo-1,3-dicarbonyl compounds is commonly best performed with p-toluenesulfonyl azide (TsNg) as the diazo-transfer reagent tScheme 3.9h). > An issue... 

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