Patent ID: 8367827

Claim:
A process for carrying out a furan ring closure reaction to transform a compound of Formula (III) to a compound of Formula (IV): wherein: R 1 and R 2 are independently selected from the group consisting of hydrogen, halogen, hydroxy, alkoxy, cyano, hydrocarbyl, substituted hydrocarbyl and NR c R d , where each of R c and R d are independently selected from the group consisting of hydrogen, hydroxy and hydrocarbyl; R 3 and R 5 are independently selected from the group consisting of hydrogen, hydrocarbyl and substituted hydrocarbyl; R 4 is selected from the group consisting of hydrogen, acyl, trialkylsilyl, tertiary-alkyl, aryl-substituted methyl, and alkoxy-carbonyl; R 6 is a substituent at C5 or C7 and is selected from hydrogen, alkyl, and acyl; and, the dashed bond between carbon atoms C7 and C8 indicates the optional presence of a carbon-carbon double bond; the process comprising contacting the compound of formula (III) with a super acid under process conditions suitable for forming a bond between the oxygen atom of the —OR 4 substituent and the C5 carbon atom to form a furan ring.