Knoevenagel kondensationen mit TiCl 4/base-IV : Umsetzungen von aldehyden und ketonen mit phosphonoessigester und methylendiphosphonsäureestern

Abstract

In the presence of titanium tetrachloride and an organic base in tetrahydrofurane, triethyl phosphonoacetic acid undergoes condensation with aliphatic and aromatic aldehydes and aromatic ketones to yield the corresponding triethyl alkylidene and arylidene phosphonoacetic acids respectively. Tetraalkyl methylenediphosphonates and aromatic or aliphatic α-branched aldehydes react under identical conditions in the same way. The largely unknown triethyl alkylidene and arylidene phosphonoacetic acids and the new tetraalkyl alkylidene and arylidene methanediphosphonic acids are easily hydrogenated either catalytically or by sodium borohydride in ethanol to give the corresponding saturated compounds in nearly quantitative yields.