Nitro- and Nitroso-alkanes

Seebach, R. Henning, F. Lehr, and J. Gonnermann, Tetrahedron Letters, 1977, 1161. 

Addition of a methylene chloride solution of chlorine (bromine or iodine) to a slurry of a primary nitroalkane salt and ice at - 78 C permits monohalogenation in good yield.  

The chemistry of electrophilic C-nitroso-compounds has been reviewed.  

This year has again emphasized the growing importance of organo-transition metal complexes in organic synthesis. In catalysed reactions the major advances have been in asymmetric catalysis with the first reports of chiral induction in catalytic epoxidation and further reports on improved catalysts for asymmetric hydrogenation and allylic alkylation. The formation of carbon-carbon bonds continues to attract attention, and several novel and potentially useful synthetic applications of organometallic complexes have been reported. 

New and more selective homogeneous catalysts continue to be developed. Very few catalysts for the homogeneous reduction of aromatic compounds are known but this year two have been reported. The first is the readily prepared rhodium complex [Rh(r -C5Me5)Cl2]2 which will reduce benzene (50°C/50atm) in the presence of a base to cyclohexane with this catalyst a high stereospecificity for all ci5-addition is observed. The other report concerns the use of salicylaldehyde complexes of copper and nickel for the catalytic reduction of aromatic rings, but there is some doubt as to whether the active catalysts are homogeneous or not. 

Reactions.—Seebach has found that aa-doubly deprotonated nitroalkanes can be prepared by addition of 2-equivalents of n-butyl-lithium in hexane to a stirred solution of the nitroalkane in THF-HMPT at —90 °C. the dilithio derivative (15) 

Nitroalkanes can be converted to carbonyl compounds in acceptable yields using vanadium(ii) chloride in aqueous dimethylformamide. Treatment of nitroalkanes with acylcarbonylferrate(o) gives a new synthetic route to amides. JViV -Disub-stituted ureas have been prepared, by the same workers, from nitroalkanes (and arenes), bromomagnesium alkylamides, and pentacarbonyliron. The catalytic hydrogenation of nitrosoalkane dimers is a useful route to symmetrical azoxy-alkanes.  

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