Evidence for a stereospecific 1,2-elimination reaction in a 1,1-diazene. Synthesis and decomposition of [N-phenyl(threo- and erythro)-2-deuterio-1-methylpropyl)amino]nitrene

Abstract

The mechanism of the formal 1,2-elimination reaction of 1,1-diazenes to alkenes is examined. The syntheses and decompositions of [N-phenyl(1-methylpropy1)aminolnitrene (6), [N-phenyl(erythro-2-deuterio-l-methylpropy1)aminolnitrene (7), and [N-phenyl(threo-2-deuteri~l-methylpropyl)amino]nitrene (8) are reported. Oxidation of 1-(1-methylpropy1)-1-phenylhydrazine (9) with nickel peroxide at 100 °C affords 1-butene, trans-2-butene, cis-2-butene, butane, and benzene in ratios of 0.59:0.300.097:0.005:1.00. Reaction of the corresponding benzenesulfonamide 10 with base at 100 "C affords similar ratios. Oxidation of l-(erythro-2-deuterio-l-methylpropyl)-1-phenylhydrazine (14) at 100 °C affords 1-butene, trans-2-butene (100 ± 2% d_1), cis-2-butene (2.8 ± 2% d_1), and butane in ratios of 0.67:0.30:0.03:0.004. Oxidation of l-(threo-2-deuterio-l-methylpropyl)-lphenylhydrazine (20) at 100 °C affords 1-butene, trans-2-butene (1.8 ± 2% d_l), cis-2-butene (97.9 ± 2% d_1), 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 °C affords similar results. Primary kinetic isotope effects for 2-butene formation from the erythroand threo-1,l-diazene diastereomers were 3.5 and 3.4. respectively. The 1,l-diazene 1,2-elimination reaction studied here is a stereospecific cis-elimination process.

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