Nitrobenzenesulfonyl Azide

Preparative Method by the reaction of o-nltrobenzenesulfonyl chloride with an aqueous acetone solution of sodium azide, first at 0 °C and then at 25 °C.  

Handling, Storage, and Precautions azides should be expected to be sensitive to electrical, thermal, and/or mechanical shock. The parent sulfonyl azide, benzenesulfonyl azide. In the crude state, detonates violently when heated. 

With a cyclic enamine, o nitrobenzenesulfonyl azide affords an A/ sulfonyl amidine following decomposition of an unstable intermediate triazoline (eq 5).  

Dipolar Cycloaddition. o-Nitrobenzenesulfonyl azide has been used for the ring enlargement-conversion of methylenecy-cloalkanes Into the homologous onitrobenzenesulfonimldocyclo-alkanes. For example, methylenecycloheptane affords the Imldo product In quantitative yield. Hydrolysis of the imide with acid then affords the corresponding ketone (eq 1).  

The reaction of onitrobenzenesulfonyl azide with an ynamlne leads to a 2-diazoalkanamldIne as the only Isolable product. An equilibrium between the amidine and the ring-closed triazole exists, however. In solution (eq 6).  

---

On reacting 109b with LDA followed by 4-nitrobenzenesulfonyl azide, the diazo compound 114 was formed along with the corresponding azide 115 (Scheme 32). 

A similar sequence with polyspiroketone 24 afforded alkylidenecyclopropanes 25, which can be ring enlarged to polyspiroketones 26 via reaction with 4-nitrobenzenesulfonyl azide. The latter transformation entails a closed homologation sequence. ... 

The most widely used application of sulfonyl azides is in the azidation of enolates and other stabilized carbanions. The main challenge here is the avoidance of the diazo transfer reaction, which leads to diazo compounds and thus makes a diastereoselective animation impossible. Addition of the enolates to the sulfonyl azide proceeds rapidly at low temperatures (—78° or lower) to give the mesomeric ion 42 (Eq. 30).318 Reagents 41, the counter ion M+, the solvent, and the quenching reagent all influence the subsequent partition between azide and diazo compound. For enolates of esters (39) and N-acyloxazolidinoncs (40) the preferred reagent is trisyl azide (41a) 4-nitrobenzenesulfonyl azide (41c) promotes diazo transfer, and tosyl azide (41b) usually leads to mixtures of the two types of products. For ester enolates 39, either lithium or potassium as the... 

Reaction of ester enolates with trisyl azide and short reaction times at —78° gives the a-azido esters in 50-70% yields 318,413,414 with 4-nitrobenzenesulfonyl azide, the diazo esters are formed almost exclusively.318 Azidomethyl phenyl sulfide and ester enolates give a-amino amides274,275 (Eq. 114),274 but the scope of this reaction has not been determined. 

Another advantage of sterically demanding trisyl azide is the selective azidation of cyclic 8-ketoesters (eq 32). Thus, the desired azidation product A was slowly formed as a single product in either THF or MeCN. In contrast, more reactive sulfonyl azides such as 4-methoxybenzenesulfonyl azide, 4-nitrobenzenesulfonyl azide, mesyl azide, triflyl azide, and tosyl azide provided not only the azidation product A but also a ring-contraction product B, a ring-opened diazo-transfer product C, and a mixture of ring-opened olefins D. The amounts of by-products B, C, and D were dependent upon the azide reagent. 

Diazo transfer to these substrates is best effected by reaction of the sodium enolate of 2 with />-nitrobenzenesulfonyl azide. A typical diazocarboximide is obtained in 85% yield after a quench with a pH 7 phosphate buffer. 

Scheme 49. 1,3-Dipolar cycloaddition of p-nitrobenzenesulfonyl azide (219) onto dispirocy-clopropanated bicyclopropylidene 56 [140]...

The 1,3-dipolar cycloaddition ofp-nitrobenzenesulfonyl azide (219) onto di-spirocyclopropanated bicyclopropylidene 56 has been used as a key step in a general repetitive procedure for the preparation of [n]rotanes 222 (Scheme 49) [140]. 

The preparation of azides using other acid halides follows a procedure similar to that for o-nitrobenzenesulfonyl azide with the exception that drop-wise addition is recommended. 

Reaction of p-nitrobenzenesulfonyl azide with alkylidenecycloalkanes 22-25187 does not yield isolable triazolines as expected, but the reaction products derived from alkenes 22 and 23 suggest a single triazoline intermediate, whereas in the case of tetrasubstituted derivative 24 both possible reaction modes are present,187 owing to weak double bond dissymmetry. Product analysis from 25 indicates some conflict between electronic and steric control in the addition, but provides evidence that electronic factors are much more important than steric effects in controlling regioselectivity.187 Reaction of the exocyclic olefins 22 and 23 appears to be controlled more by the interaction of the LUMO of the azide and the HOMO of the alkene.187 p-Nitrobenzenesulfonyl azide is reported to react with members of the novel... 

Similarly, spirotriazoline intermediates from the addition of p-nitrobenzenesulfonyl azide to exocyclic olefins 22 and 23 give a single ring-expanded sulfonimide (97),18 7 190-19 2 whereas those derived from 24 yield two sulfonimides, 97 from ring expansion and 98 from methyl migration.187 Four... 

Evans and co-workers have reported successful diazo transfer from p-nitrobenzenesulfonyl azide (PNBSA) to the enolate derivatives of an N-acyloxazolidinone and a benzyl ester (a) Evans, D. A. Britton, T. C. Ellman, J. A. Dorow, R. L. J. Am. Chem. Soc. 1990, 112, 4011. However, we have not been able to achieve efficient diazo transfer to ketone enolates employing these conditions. For example, exposure of the lithium enolate of acetophenone to 1.2 equiv of PNBSA in THF at -TS C for 15 min gave a-diazoacetophenone in only 21% yield. 

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 thermal decomposition of sulfonyl azides, like azido formates, appears to involve nitrene intermediates . The thermolysis of benzenesulfonyl azide is first order and the rate coefficient is relatively insensitive to solvent changes or substituent effects . o-Nitrobenzenesulfonyl azide decomposes with evolution of nitric oxide and nitrogen the rate of azide disappearance however, is about the same as that for other benzenesulfonyl azides and it appears that the reaction leading to NO can be explained by an intramolecular rearrangement in the nitrene intermediate. This is in contrast to the decomposition of o-nitrophenyl azide (vide infra) where rearrangement occurs in the transition state of the rate-determining step. 

Methyl 2-oxo-l-indanecarboxylate (133) with p-nitrobenzenesulfonyl azide gave methyl 2-[A -(p-nitrobenzenesulfonyl)carbamoyl]-3,4-dihydro-l-phtha-lazinecarboxylate (134) (or tautomer) (EtsN, THF, 0°C 20" C, 1 h crude) and thence methyl 4-[A -(p-nitrobenzenesulfonyl)carbamoyl]-l-phthalazine-carboxylate (135) (tetrachloro-l,2-benzoquinone, PhH, reflux, 10 min %) stmcture (135) was confirmed by X-ray analysis and a synthetic mechanism... 

Dihydropyran added at room temp, to m-nitrobenzenesulfonyl azide in tetra-hydrofuran, and the product isolated after 30 hrs. at room temp. N-(m-nitro-... 

A stirred solution of 5.0 gm (0.077 mole) of sodium azide in 75 ml of acetone is cooled to —10°C while 15 gm (0.66 mole) of o-nitrobenzenesulfonyl chloride dissolved in 75 ml of acetone is added dropwise. The reaction mixture is stirred for 1 hr at —10°C and for 1 hr at room temperature. The solution is filtered and diluted with 500 ml of ice water. The yellow product is removed by filtration, washed with water and dried. The product is dissolved in 150 ml of warm ethanol and freed from any insoluble material by filtration. The clear filtrate is cooled to afford 12.0 gm (80%), m.p. 71°-73°C. 

---