AROMATIZATION OF 2,2,5-TRIALKYL-SUBSTITUTED 2,5-DIHYDROFURANS AND FACTORS AFFECTING THEIR STABILIZATION

Abstract

We demonstrate that the synthesis of 5-methoxy-2,2,5-trialkyl-substituted 2,5-dihydrofurans containing unprotected hydroxymethyl group at the C-2 position involves aromatization via fragmentation involving С–С bond cleavage, resulting in the formation of 2,5-disubstituted furans and carbonyl compounds. 2,5-Dihydrofurans bearing an ester group at the С-2 position were stable. It was found that 2,2,5-trialkyl-substituted 2,5-dihydrofurans containing a hydroxymethyl or carbonyl group in the side chain could aromatize through auto-oxidation, which was facilitated by adjacent functional groups (sulfo- or pivaloyl groups).