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The reaction of xenon difluoride with enamino lactone 3 furnished the new α-fluoro aldehyde 7, whereas reaction of 3 with anhydrous HF led to racemic dihydro-β-campholenolactone 6. Acid-catalysed rearrangement of α-ethylidenelactone 4 proceeded with retention of configuration to give β-campholenolactone 8. Nitrosation of the novel bicyclic enamino lactone 6 afforded the corresponding oxime 9, while acid-catalysed treatment with primary amines, 2-methyl-1H-indole, potassium cyanide and hydrazine hydrochloride, furnished the dimethylamine substitution products 11–13 and the ‘ring switched’ product 14. The structures were determined by 2D NMR techniques, NOESY spectroscopy and X-ray diffraction.

Stereoselective additions to the exocyclic C C double bond of some (1R,3E,4S)-3-alkylidene-1,7,7-trimethylbicyclo[2.2.1]heptan-2-ones and (1R,4E,5S)-4-alkylidene-1,8,8-trimethyl-2-oxabicyclo[3.2.1]octan-3-ones were studied. All additions took place predominantly from the less hindered endo-face of the methylidene compounds to give the corresponding exo-adducts as the major isomers. Thus, catalytic hydrogenations afforded the α-alkylated (1R,3R,4R)-1,7,7-trimethylbicyclo[2.2.1]heptan-2-ones and (1R,4R,5R)-1,8,8-trimethyl-2-oxabicyclo[3.2.1]octan-3-ones in 28–100% de. Similarly, 1,3-dipolar cycloadditions of 2,4,6-trisubstituted benzonitrile oxides gave the corresponding spiro cycloadducts in 66–100% de. The structures were determined by 2D NMR techniques, NOESY spectroscopy and X–ray diffraction.

Reductions of (1R,3R,4R)-3-([1,2,4]triazolo[4,3-x]azin-3-yl)-1,7,7-trimethylbicyclo[2.2.1]heptan-2-ones and their lactone analogues, prepared from (1R)-(+)-camphor, were studied. Catalytic hydrogenation selectively led to partial saturation of the [1,2,4]triazolo[4,3-x]azine residue, while in reactions with borane–methylsulfide coordination of borane to the 1-position of [1,2,4]triazolo[4,3-x]azine system took place. On the other hand, activation of the carbonyl group in (1R,3R,4R)-3-([1,2,4]triazolo[4,3-x]azin-3-yl)-1,7,7-trimethylbicyclo[2.2.1]heptan-2-ones with boron trifluoride etherate followed by reaction with borane–methylsulfide furnished the corresponding isoborneols, stereoselectively. The structures of all representative compounds were confirmed by X-ray diffraction.

4-[(Heteroaryldiazenyl)methylidene] and 4-([1,2,4]triazolo[4,3-x]azin-3-yl) substituted (1R,5R)-4-1,8,8-trimethyl-2-oxabicyclo[3.2.1]octan-3-ones 6/6′ and 7/7′ were obtained in a one-pot transformation of the enamino lactone 2 with hydrazinoazines 3a–g followed by oxidation of the intermediate mixture of isomeric enehydrazines 4/4′ and hydrazones 5/5′ with lead tetraacetate. The oxidation selectivity was dependent on the ratio of isomeric intermediates 4/4′ and 5/5′. Treatment of 7b with lead tetraacetate led to α-acetoxylated compound 11, while bromination of 9b afforded a 1:1 mixture of α-bromination products 12 and 12′, which were separated by medium pressure liquid chromatography (MPLC). The structures of intermediates and products were confirmed by NMR and X-ray diffraction.

(1R,4E,5S)-4-Oximino-1,8,8-trimethyl-2-oxabicyclo[3.2.1]octan-3-one 9 was prepared in three steps from (1R)-(+)-camphor 1 via nitrosation of (1R,4E,5S)-4-[(dimethylamino)methylidene]-1,8,8-trimethyl-2-oxabicyclo[3.2.1]octan-3-one 8. Catalytic hydrogenation of 9 under various reaction conditions afforded (1R,4S,5S)-4-amino-1,8,8-trimethyl-2-oxabicyclo[3.2.1]octan-3-one derivatives 11, 13, and 15b. On the other hand, reduction of 9 with Grignard reagents led to two types of products, (1R,4S,5S)-4-dialkylamino-1,8,8-trimethyl-2-oxabicyclo[3.2.1]octan-3-ones 15b and 15c and/or 2-substituted (1E)-1-[(1S,3R)-3-hydroxy-2,2,3-trimethylcyclopentyl]ethane-1,2-dione 1-oximes 16a,b and 15d–f. The structures of compounds 9, 10′, 15b, and 16b were determined by X-ray diffraction.

N-Substituted (1R,5S)-4-aminomethylidene-1,8,8-trimethyl-2-oxabicyclo[3.2.1]octan-3-ones were prepared in three steps from (1R)-(+)-camphor via coupling of (1R,4E,5S)-3-[(dimethylamino)methylidene]-1,8,8-trimethyl-2-oxabicyclo[3.2.1]octan-3-one with primary amines. N,N′-Bis-{[(1R,5S)-1,8,8-trimethyl-3-oxo-2-oxabicyclo[3.2.1]oct-4-ylidene]methyl}benzene-1,2-diamine was used as the ligand in the preparation of the corresponding coordination compounds with palladium(II), copper(II) and nickel(II). The structures were determined by 2D NMR techniques, NOESY spectroscopy and X–ray diffraction.