An Improved Liquid-Phase Synthesis of Simple Alkylpyridines
作者:J. Ian Grayson、Rolf Dinkel
DOI:10.1002/hlca.19840670811
日期:1984.12.19
The synthesis of pyridines from mixtures of aldehydes or ketones NH3 in the liquid phase has been reinvestigated, using continuous dosage of the carbonyl components to the reaction mixture. The main product from the reaction of acetaldehyde and formaldehyde is 3-methylpyridine (6), which is also the main product from the reaction of acrolein or a mixture of crotonaldehyde and formaldehyde under the
alpha-Mono- or alpha-dialkylated aldehydes undergo cyclotrimerization in the presence of dibromotriphenylphosphorane (PPh(3)Br(2)) to afford cyclopentenones or tetrasubstituted tetrahydrofurans in good yields. These transformations proceed by a tandem aldol dimerization/Nazarov reaction or a tandem aldol dimerization/Prins cyclization.