Evidence for a Stereospecific 1,2-Elimination Reaction in a 1,1-Diazene. Synthesis and Decomposition of nitrene

Article abstract of DOI:10.1021/jo00155a008

The mechanism of the formal 1,2-elimination reaction of 1,1-diazenes to alkenes is examined.The syntheses and decompositions of nitrene (6), nitrene (7), and nitrene (8) are reported.Oxidation of 1-(1-methylpropyl)-1-phenylhydrazine (9) with nickel peroxide at 100 deg C affords 1-butene, trans-2-butene, cis-2-butene, butane, and benzene in ratios of 0.59:0.30:0.097:0.005:1.00.Reaction of the corresponding benzenesulfonamide 10 with base at 100 deg C affords similar ratios.Oxidation of 1-(erythro-2-deuterio-1-methylpropyl)-1-phenylhydrazine (14) at 100 deg C affords 1-butene, trans-2-butene (100+/-2percent d₁), cis-2-butene (2.8+/-2percent d₁), and butane in ratios of 0.67:0.30:0.03:0.004.Oxidation of 1-(threo-2-deuterio-1-methylpropyl)-1-phenylhydrazine (20) at 100 deg C affords 1-butene, trans-2-butene (1.8+/-2percent d₁), cis-2-butene (97.9+/-2percent d₁), and butane in ratios of 0.77:0.11:0.11:0.009.Reaction of the corresponding benzenesulfonamides 15 and 21 with base at 100 deg C affords similar results.Primary kinetic isotope effects for 2-butene formation from the erythro- and threo-1,1-diazene diastereomers were 3.5 and 3.4, respectively.The 1,1-diazene 1,2-elimination reaction studied here is a stereospecific cis-elimination process.