A variety of spirocyclopropane-annelated tetrahydropyridinones of types 14/15 and 18/19 have been prepared in good yields (68−80%) by means of 1,3-dipolar cycloadditions between nitrones 25, 31, and 34 and cyclopropylidenespiropentane (7) and 7-cyclopropylidenedispiro[2.0.2.1]heptane (8), with subsequent thermal rearrangement. While the overall reactions of nitrones 25 and 31 with 7-cyclopropylidenedispiro[ 2.0.2.1]heptane (8) occurred with the commonly observed regioselectivity (i.e., the initially formed cycloadducts of type A variety of spirocyclopropane-annelated tetrahydropyridinones of types 14/15 and 18/19 have been prepared in good yields (68−80%) by means of 1,3-dipolar cycloadditions between nitrones 25, 31, and 34 and cyclopropylidenespiropentane (7) and 7-cyclopropylidenedispiro[2.0.2.1]heptane (8), with subsequent thermal rearrangement. While the overall reactions of nitrones 25 and 31 with 7-cyclopropylidenedispiro[ 2.0.2.1]heptane (8) occurred with the commonly observed regioselectivity (i.e., the initially formed cycloadducts of type A variety of spirocyclopropane-annelated tetrahydropyridinones of types 14/15 and 18/19 have been prepared in good yields (68−80%) by means of 1,3-dipolar cycloadditions between nitrones 25, 31, and 34 and cyclopropylidenespiropentane (7) and 7-cyclopropylidenedispiro[2.0.2.1]heptane (8), with subsequent thermal rearrangement. While the overall reactions of nitrones 25 and 31 with 7-cyclopropylidenedispiro[ 2.0.2.1]heptane (8) occurred with the commonly observed regioselectivity (i.e., the initially formed cycloadducts of type 12/13 rearranged to give compounds 29, 30, and 33 as major products), the reactions of 31 and 34 with cyclopropylidenespiropentane (7) and of 34 with 7-cyclopropylidenedispiro[ 2.0.2.1]heptane (8) showed an opposite trend. Thermal rearrangement of compound 27 gave a mixture of pyridinone 29 and ring-opened product 30 (19 and 58% yields, respectively).
Di- and Trispirocyclopropanated Tetrahydropyridinones by a One-Pot Sequence of 1,3-Dipolar Cycloaddition of Nitrones to Spirocyclopropanated Bicyclopropylidenes and Subsequent Thermal Rearrangement / M. Gensini; S. I. Kozhushkov; D. Frank; D. Vidovic; A. Brandi; A. de Meijere. - In: EUROPEAN JOURNAL OF ORGANIC CHEMISTRY. - ISSN 1434-193X. - STAMPA. - 2003:(2003), pp. 2001-2006. [10.1002/ejoc.200200696]
Di- and Trispirocyclopropanated Tetrahydropyridinones by a One-Pot Sequence of 1,3-Dipolar Cycloaddition of Nitrones to Spirocyclopropanated Bicyclopropylidenes and Subsequent Thermal Rearrangement
BRANDI, ALBERTO;
2003
Abstract
A variety of spirocyclopropane-annelated tetrahydropyridinones of types 14/15 and 18/19 have been prepared in good yields (68−80%) by means of 1,3-dipolar cycloadditions between nitrones 25, 31, and 34 and cyclopropylidenespiropentane (7) and 7-cyclopropylidenedispiro[2.0.2.1]heptane (8), with subsequent thermal rearrangement. While the overall reactions of nitrones 25 and 31 with 7-cyclopropylidenedispiro[ 2.0.2.1]heptane (8) occurred with the commonly observed regioselectivity (i.e., the initially formed cycloadducts of type A variety of spirocyclopropane-annelated tetrahydropyridinones of types 14/15 and 18/19 have been prepared in good yields (68−80%) by means of 1,3-dipolar cycloadditions between nitrones 25, 31, and 34 and cyclopropylidenespiropentane (7) and 7-cyclopropylidenedispiro[2.0.2.1]heptane (8), with subsequent thermal rearrangement. While the overall reactions of nitrones 25 and 31 with 7-cyclopropylidenedispiro[ 2.0.2.1]heptane (8) occurred with the commonly observed regioselectivity (i.e., the initially formed cycloadducts of type A variety of spirocyclopropane-annelated tetrahydropyridinones of types 14/15 and 18/19 have been prepared in good yields (68−80%) by means of 1,3-dipolar cycloadditions between nitrones 25, 31, and 34 and cyclopropylidenespiropentane (7) and 7-cyclopropylidenedispiro[2.0.2.1]heptane (8), with subsequent thermal rearrangement. While the overall reactions of nitrones 25 and 31 with 7-cyclopropylidenedispiro[ 2.0.2.1]heptane (8) occurred with the commonly observed regioselectivity (i.e., the initially formed cycloadducts of type 12/13 rearranged to give compounds 29, 30, and 33 as major products), the reactions of 31 and 34 with cyclopropylidenespiropentane (7) and of 34 with 7-cyclopropylidenedispiro[ 2.0.2.1]heptane (8) showed an opposite trend. Thermal rearrangement of compound 27 gave a mixture of pyridinone 29 and ring-opened product 30 (19 and 58% yields, respectively).
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