Synthesis of Norbornanones with a Geminal Dimethyl Group

Article abstract of DOI:10.1007/BF00909674

The synthesis of gem-dimethylnorbornanones is described.One synthetic pathway after a Diels-Alder reaction involves the transformation of the nitro group into the oxo group with subsequent methylation into the geminal dimethyl product.A shorter way by <4 + 2>-cycloaddition of cyclopentadiene with a suitable dimethylated dienophile (e.g. 2-methyl-1-nitropropene) failed, probably by steric hindrance of the dienophile. 7-Oxanorbornanones with a gem -dimethyl group could not be prepared.A second synthetic approach to gem-dimethylnorbornanones is opened by Lewis acid catalyzed rearrangement of cyclohexenylcarbaldehydes. - Keywords: Camphenilone; Diels-Alder reaction; Homonorbornanone; α-Methylation of carbonyls; Nef-reaction; Norepifenchone