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Steric factors in the cyclization of 4-azaheptane-2,6-diones to dehydropiperid-3-ones and the stereochemistry of reduction of 2,2-dimethyl- and 5-neopentylpiperid-3-ones

Journal Article · · Bull. Acad. Sci. USSR, Div. Chem. Sci. (Engl. Transl.); (United States)
OSTI ID:6226045
The neopentyl substituent in the azadiketones of the type (Ib) completely blocks the cyclization to the dehydropiperidine systems with the participation of the acetonyl carbonyl as the electrophile. In such azadiketones, the geminal substitution at the carbon atom adjoining the nitrogen is less effective in its influence on the regioselectivity of the cyclization by comparison with the influence of substitution at the nitrogen. In the saturated 3-ketopiperidines, the axial substituent at C/sup 2/ largely blocks the e-coordinate of the approach of the hydride nucleophiles to the carbonyl or the e-adsorption in catalytic hydrogenation. The steric influence of the neopentyl substituent at C/sup 2/ on the carbonyl depends on the specificity of the particular reagent and can surpass the influence of the tert-butyl group.
Research Organization:
N.D Zelinskii Institute of Organic Chemistry, Moscow, USSR
OSTI ID:
6226045
Journal Information:
Bull. Acad. Sci. USSR, Div. Chem. Sci. (Engl. Transl.); (United States), Journal Name: Bull. Acad. Sci. USSR, Div. Chem. Sci. (Engl. Transl.); (United States) Vol. 34:10; ISSN BACCA
Country of Publication:
United States
Language:
English