3-Hydroxy-4-nitro-cyclohexanones from Ketones and 4-Nitrobutanoyl Chloride. A Ring Enlarging Five-Ring Annulation

Article abstract of DOI:10.1002/hlca.19810640314

The 6-nitro-1,3-diketones 5, 8, 9, 10, and 11, prepared by a 1:1 acylation at the C-atom of non-hindered lithium enolates with 4-nitrobutanoyl chloride according to equation 3, are cyclized with sodium hydrogen carbonate in aqueous tetrahydrofuran to give the hydroxy-nitro-ketones 13-17.Such cyclic nitroaldols are not formed from the cyclopentanone, -heptanone, and -octanone, nor from the aryl derivatives 4, 6, 7 and 12, respectively.Except for the vicinally trisubstituted compound 14, the cyclization products are isolated in diastereomerically pure form.A crystal structure X-ray analysis reveals the trans-decalone and the cis-β-nitroalcohol configurations of the product 13 from cyclohexanone.Acetalization to 21-25 and catalytic hydrogenation of the nitro groups furnishes the amino alcohols 27-31 which are substrates for the Tiffeneau-Demjanow rearrangement.From the stereoelectronic control of this sextett rearrangement we deduce the configurations of the 1,4-diketones 35, 36, 39, 40, 43, 44, 46, and 47 formed under kinetic or thermodynamic conditions.The six-ring annulation with nitrobutanoic acid and the subsequent rearrangement are shown in Scheme 6; the sequence of reactions described here allows to carry out a ring enlargement of a cyclic ketone by one C-atom, with simultaneous annulation of a cyclopentanone ring.