Synthesis of Spiro[furan-2,1′-isoindolin]-3′-ones from 2-(4-Hydroxybut-1-yn-1-yl)benzonitriles and Aryl Aldehydes under the Action of Triflic Acid

The synthesis of spiro[furan-2,1'-isoindolin]-3'-ones from 2-(4-hydroxybut-1-yn-1-yl)benzonitriles and aryl aldehydes is demonstrated. It involves the initial formation of dihydrofuranylideneisoindolinone via intramolecular sequential Prins and Ritter reactions, followed by the ring opening of the furanyl moiety to generate N-acyliminium ions and alcohols for the final cyclization reaction, and the spiro-cyclic compounds are produced in moderate to good yields. It is a one-pot, three component reaction in which one new quaternary carbon, two five membered rings, one C-N bond, two C-O bonds, and one C-C bond are formed. The reaction is carried out with a Bronsted acid from 0 degrees C to room temperature within a short period of time.

Automated summary

This study demonstrates the synthesis of spiro[furan-2,1'-isoindolin]-3'-ones from 2-(4-hydroxybut-1-yn-1-yl)benzonitriles and aryl aldehydes. The reaction involves the formation of dihydrofuranylideneisoindolinone through intramolecular Prins and Ritter reactions, followed by ring opening and cyclization to produce the spiro-cyclic compounds.