Novel approach for the synthesis of 2-arylfuro[3,2-b]pyran-3-carbaldehydes based on acid-catalyzed cyclization of allomaltol containing enaminones

Abstract

The novel and efficient approach for the synthesis of various 2-arylsubstituted furo[3,2-b]pyran-3-carbaldehydes was developed. The studied method is based on acid-catalyzed cyclization of enaminones bearing allomaltol fragment. The distinctive feature of the suggested protocol is the other direction of heterocyclization of starting enaminoketones in contrast to the previously described approach leading to 3-aroylfuro[3,2-b]pyranes. The advantages of this synthesis are easily accessible starting compounds, mild reaction conditions, and simple workup procedure avoiding chromatographic purification. The synthetic utility of obtained aldehydes was demonstrated by the preparation of various derivatives. The structure of one furo[3,2-b]pyran-3-carbaldehyde was proved by X-ray diffraction.