Aliphatic diazo compounds. XII. The synthesis of 5-endo-hetero-atom-substituted 3-diazo-2-norbornanones and the proton magnetic resonance spectra of these diazo ketones and their precursors

Abstract

Treatment of 6-e~~do-acetoxy-5,5-dimethyl-2,3-norbornanedione (6) with tosylhydrazine gives the 2-tosylhydrazone (7), which is converted to 5-endo-acetoxy-3-diazo-6,6-dimethyl-2-norbornanone (1) by basic alumina; the exclusive formation of the 2-tosylhydrazone is ascribed to the smaller steric effect of the etldo C-6 acetoxyl relative to the endo C-5 methyl group. The 6-endo-methoxy analogue of 6, 17, and the related 6-endo-chloro-and 6-etldobromo-l,5,5-trimethyl-2,3-norbornanediones (23 and 26) are similarly converted to the corresponding a-diazo ketones 2-4. The 'H nmr spectra of the diazo ketones 1-4 have their C-1 bridgehead proton signals shifted to higher field relative to the corresponding bridgehead proton signals of the related a-diketones, whereas the C-4 bridgehead proton signals of 1 and 2 are shifted to lower field in relation to the corresponding a-diketone signals. The 'H nmr spectra of the a-diketones show an unusual long range coupling (4J 2 1 Hz) between the C-4 bridgehead protons and the exo C-6 protons that is significantly smaller or absent in the spectra of the related diazo ketones and monoketones. In all of these types of compound an endo-methoxyl or -acetoxyl group at C-5(6) shifts the exo and etldo C-6(5) methyl signals to lower and higher field, respectively, whereas an endo-halo substituent at C-5(6) shifts both the exo and endo C-6(5) methyl signals to lower field.

Aliphatic diazo compounds. XIV. The synthesis of 7-substituted 3-diazo-2-norbornanones and the infrared and proton and carbon-13 nuclear magnetic resonance spectra of these diazo ketones and their precursors

“…The ir spectra of the 2,3-norbornanediones 40-43 (Table 3) show two bands in the carbonyl-stretching region at 5.60-5.63 and 5.68-5.70 pm resulting from vibrational coupling, as has been observed previously for compounds of this type (23). In the 'H nrnr spectra of 40 and 41 the methyl proton signals appear as simple doublets, since the methyl groups in each compound are no longer diastereotopic.…”

“…As in the case of the monoketones the tert-butyl methyl signal of the syn isomer 42 is shifted upfield relative to that of the anti isomer 43, while there is no significant difference in the chemical shifts of the isopropyl methyl signals of 40 and 41. Two-proton multiplets at 6 2.93-3.07 ppm in the spectra of 40-43 are assigned to the bridgehead protons (H-1,4) on the basis of earlier assignments for the bridgehead proton signals of 2,3-norbomanedione (51) (6 3.06 ppm (24)), and related compounds (23).…”

Bridged-ring steroids. III. The synthesis of bridged steroids with a bicyclo[2.2.1]heptane ring B system

“…Thus it is the signal of the C-18 methyl group that is shifted downfield in the second isomer relative to the first and the structural assignments are as given. This argument implies that the chemical shifts of the C-19 methyl signals are very similar in the two isomers, which is in accordance with the observation that the endo-methyl protons in 5,5-dimethyl-and 6,6-dimethylbicyclo[2.2. llheptan-2-ones have closely similar chemical shifts (7). Independent chemical corroboration of the individual structural assignments was obtained as shown in Scheme 3.…”