Phosphonomethylated Acetoxymethyl Derivatives of Acetylfurans and Alkyl Furoates with Neighboring Location of Substituents: Synthesis and Following Transformations

Abstract— Methods of synthesis of phosphonmethylated acetoxymethyl derivatives of acetylfurans and alkyl furoates have been developed and their methanolysis was studied. It has been found that due to the high acidity of hydroxymethylfuran derivatives, the reaction proceeds to completion only with an equivalent amount of methylate. If the acetoxymethyl and diethoxyphosphoryl groups occupy adjacent positions in the furan ring, transesterification of the phosphonate group occurs, accompanied by the destruction of P–C bond. The ester group is transesterified in any case. The resulting alcohols are oxidized by the dimethyl sulfoxide–acetic anhydride system or by the complex of chromium trioxide with pyridine to the corresponding aldehydes. The P–C bond is not affected in this case. The resulting aldoketones react with hydrazine hydrate to form furo[2,3-d]- or furo[3,4-d]pyridazines, depending on the location of substituents in the furan ring. In the case of aldoesters having similar structure, the reaction stops at the stage of formation of hydrazones.