Three-Component Synthesis of Substituted Perhydropyrans from β-Styrylmalonates, Aldehydes, and Alkoxyaluminum
Denis D Borisov1, Roman A Novikov1,2, Yury V Tomilov1
1Russian Academy of Sciences, N. D. Zelinsky Institute of Organic Chemistry, 47 Leninsky prosp., 119991 Moscow, Russian Federation.
Abstract:
A three-component synthesis of substituted dimethyl dihydro-2H-pyran-3,3(4H)-dicarboxylates in up to 80% yields by the reaction of β-styrylmalonates with aromatic or aliphatic aldehydes in the presence of ROAlCl2 prepared in advance either by exposure of EtAlCl2 with air access or by mixing equimolar amounts of AlCl3 with a primary or secondary alcohol has been developed. If EtAlCl2, itself, is used, dihydro-2H-pyran-3,3(4H)-diesters are not formed at all, while dimerization of styrylmalonates by (4 + 2)-annulation-type to give substituted tetrahydronaphthalenes is the main process. The possibility of using the CH-O-Al fragment of alkoxyaluminum dichlorides in cycloaddition reactions with α-CH-functionalization has been shown for the first time.
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