Reduction of nitro- and nitroso-compounds by tervalent phosphorus reagents. Part IV. Mechanistic aspects of the reduction of 2,4,6-trimethyl-2′-nitrobiphenyl, 2-nitrobiphenyl, and nitrobenzene
- 1 January 1969
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society C: Organic
- No. 20,p. 2808-2813
- https://doi.org/10.1039/j39690002808
Abstract
Reduction of 2′,4′,6′-trimethyl-2-nitrobiphenyl by triethyl phosphite gives 2-amino-2′,4′,6′-trimethylbiphenyl and triethyl N-(2′,4′,6′-trimethylbiphenyl-2-yl)phosphorimidate. The same reduction, carried out in cumene or in t-butylbenzene gives, additionally, 8,10-dimethylphenanthridine, and, in cumene, 2,3-dimethyl-2,3-diphenyl-butane, indicating the intermediacy of a triplet nitrene. Reduction of nitrobenzene by diethyl methylphosphonite in an excess of diethylamine gives 2-diethylamino-3H-azepine (83%), while the corresponding reaction with 2-nitrobiphenyl gives 2-diethylamino-3-phenyl-3H-azepine (13%) in addition to carbazole (63%), pointing to an intermediate similar to that present in decompositions of azides, i.e. a nitrene or nitrenoid species, the nature of which is discussed. The order of reducing reactivity of a series of tervalent phosphorus reagents towards 2-nitrobiphenyl is (EtO)2PMe (Et2N)3P (EtO)P(NEt2)2 > (EtO)3P (PriO)3P PCl3(inactive).Keywords
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