P Nitrobenzenesulfonyl azide

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

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. ... 

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... 

Related Reagents, p-toluenesulfonyl azide and methane-sulfonyl azide have been used widely for diazo transfer to stabilized enolates. The latter reagent simplifies isolation of the desired product, but is potentially explosive and must be handled with care. Relative to other aryl analogs, the electron-deficient p-nitrobenzenesulfonyl analog favors diazo transfer to imide enolates. ... 

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. 

Cleavage reactions of A -benzyl-, A -o-nitrobenzenesulfonyl-, and A -tosylepi-mino- derivatives of 1,6-anhydro-p-D-hexopyranoses with azide and halide anions, halo acids, and benzyl-derived nucleophiles (amine, alcohol, thiol) have been studied extensively in the past decade. 

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