Disilanes have been found to represent a new class of deoxygenating agents for aryl nitro compounds. Semiquantitative investigation of the effect of disilane structure on the deoxygenation of 2-nitrobiphenyl (1) at 240°, which yielded 2-aminobiphenyl (3) and carbazole (4), indicated only moderate reduction rate differences among those disilanes studied, with hexachlorodisilane (SisCle) and hexaphenyldisilane (SizPhe) being the most and least reactive, respectively. In contrast, the relative ratio of 4:3 was markedly dependent on disilane structure and varied between limits of ~70:1 and 1:35 for reduction with, respectively, cyclic 1,2-disilacyclopentene derivative 6 and SÍ2CI6. Deoxygenation of nitrobenzene (7a), o-nitrotoluene (7b), and p-nitrotoluene (7c) with hexamethyldisilane (SiaMes) gave their corresponding amines and azo coupling products, with AG1220o = 41 kcal/mol for the pseudo-first-order reduction of 7a in excess SisMes-Qualitative comparison of SisMee deoxygenation rates for 1 and 7a-c at 240°revealed that relative substrate reactivities were not in accord with expectations based on simple steric considerations. Failure of 2-nitrosobiphenyl to undergo deoxygenation by SiaMes has led to the suggestion that disilane reduction of 1 and, by extension, other nitro aromatics does not proceed in a stepwise fashion via nitroso intermediates. Mechanisms which accommodate this restriction and account for the observed stoichiometry and products are discussed in terms of possible transient nitrene species. Attempts to carry out low-temperature photochemical deoxygenation of 1 with SiaMee proved unsuccessful.
Phenylhydroxylamin (II) liefert mit Triäthylamin und Trimethylchlorsilan lediglich Azobenzol (I), während die Umsetzung von Butyllithium und Trimethylchlorsilan je nach den stöchiometrischen Anteilen zu O‐Mono‐ und N,O‐Bis‐trimethylsilyl‐Verbindungen (III) bzw. (IV) führt.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.