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. 62, 1751 (1984).syn-and anti-7-lsopropyl-2-norbornanone (5 and 6) were prepared by catalytic hydrogenation of 7-isopropylidene-2-norbornanone; syri-and anti-7-benzhydryl-2-norbornane (9 and 10) were prepared in analogous fashion. Kctones 5 and 6 and syrl-and arlti-7-tert-butyl-2-norbornanone (7 and 8) were converted to the corresponding 3-diazo-2-norbornanones 1-4 via the monotosylhydrazones 44-47 of the corresponding a-diketones 40-43. The 'H and "C nmr spcctra of 1-10,40-47, and thcir precursors have been analyzed. The 'H nmr spectra of the diazo ketones 1-4 have their C-I and C-4 bridgehead proton signals shifted to higher and lower field, respectively, relative to the bridgehead signals of thc corresponding dikctones. Thc "C nmr spectra of all pairs of bicyclic epimers shown y-garrche shielding effects by the 7-substitucnt at (sp3) C-3 in thc syrl compounds and at C-5 and C-6 in the arlti compounds. A converse effect is found at (sp') C-2 (and C-3 in the diketoncs). Comparison of the magnitude of the shielding effects of C-7 methyl, isopropyl, benzhydryl, and tert-butyl substituents gives evidence of 6 deshielding effects at C-3 in the syrl compounds and at C-5 and C-6 in thc onti compounds by methyl substitucnts on C-8.PETER YATES et JOHN DAVID KRONIS. Can. J. Chem. 62, 1751 (1984.On a prCparC Ics isopropyl-7 norbornanones-2 syrl et anti (5 et 6) par hydrogenation catalytique de I'isopropylidene-7 norbornanone-2; on a prCparC les benzhydryl-7 norbornanones-2 syrl et nrlti (9 et 10) d'unc manikre semblablc. On a transform6 les cCtones 5 et 6 ainsi que les tert-butyl-7 norbornanones-2 sytl et anti (7 et 8) en leurs diazo-3 norbornanones-2 correspondantes (1-4) par le biais des monotosylhydrazones 44-47 des a-dicCtones correspondantes 40-43. On a analysC les spectrcs rmn du ' H et du "C des composCs 1-10 et 40-47 et de leurs prCcurseurs. Dans les spectres rmn du 'H des diazocCtones 1-4, les signaux des protons en tCte de pont (C-l et C-4) sont dCplacCs respectivcment vers des champs plus haut et plus bas, par rapport aux signaux des protons dans les positions Cquivalentes des dicttones correspondantes. Les spectrcs rmn du '.'c de chacune des paires d'Cpimkres bicycliques prtsentent tous des effets de blindage y-gauche, dus aux substituants en position 7 et affectant la position C-3 (sp3) des composCs syrl et les positions C-5 et C-6 dcs composts anti. On observe un effet inverse au niveau de C-2 (sp') (et de C-3 dans les dicttones). Une comparaison de I'amplitude dcs cffets de blindage provoquCs par les substituants mCthyle, isopropyle, benzhydrylc et tert-butyle en C-7 suggkre que les substituants mCthyles cn C-8 provoquent des effets de dtblindage 6 en C-3 dans les composCs syn et en C-5 et C-6 dans les composCs anti.[Traduit par le journal]In connection with our studies on the acid-catalyzed decomposition of a-diazo ketones (1, 2), we required pairs of 3-diazo-2-norbornanones with bulky syt7-and anti-7 substituents. We describe here the synthesis of the diazo ketones 1-4, prepared for this purpose, and di...

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Some analogs of chorismate (V) such as (I) are synthesized to study the structural requirements for mutase‐catalyzed Claisen rearrangement of type (I) → (II) by chorismate mutase‐prephenate dehydrogenase from Escherichia coli.