N-Alkylation of 2,6-Dichloropurine Hydrochloride with a Variety of Alcohols over Alumina Catalyst

Abstract

2,6-Dichloropurine hydrochloride reacts with various types of alcohols using different alumina catalysts and converts into its N-9-alkyl-2-chloro-6-hydroxy-9H-purine products to an extent of 49–74%. The product selectivity depends on the stability of carbocation generated from the alcohol. More stable carbocation formulates both N-7 and N-9-alkyl-2,6-dichloropurine products, whereas the less stable carbocation results in exclusively N-9-alkyl-2-chloro-6-hydroxy-9H-purine. The catalytic activity of alumina prepared using the sol-gel method has larger Brunauer, Emmett, and Teller (BET) surface area and hence shows significantly greater catalytic activity than the commercially available alumina samples.

Keywords:

• Alcohol
• alkylation
• alumina
• 2,6-dichloropurine hydrochloride

Notes

^a Reaction conditions: 2,6-dichloropurine hydrochloride, 1.0 g; alcohol, 25.0 ml; and alumina catalyst, 450 mg.

^b Isolated yield, flash column chromatography using silica gel.

^c Isolated yield, flash column chromatography using alumina neutral.

^a Reaction conditions: 2,6-dichloropurine moiety, 1.0 m equiv; aryl amine, 2.0 m equiv; and THF solvent, 100 rel. vol.

^b Isolated yield.