反应详情

On monitoring this reaction by thin layer chromatography, it was determined that the condensation of diacetyl guanine with dioxolane-diacetate in the presence of acidic catalyst produced N7 -isomer first, which was partially converted to N9 -isomer to reach an equilibrium in the ratio of 3/2 in favor of N9 -isomer. Under these condensation conditions, pure N7 - or N9 -acyclovir diacetate could be converted to give the same equilibrated mixture. This observation resulted in one of the embodiments of the improved process for the production of acyclovir of the present invention. When diacetyl guanine (4) almost disappeared during the condensation reaction, the reaction mixture was concentrated to dryness in vacuo, during which time the ratio of N9 /N7 -isomer continuously changed from approximately 3/2 to nearly one spot (N9 -isomer) as indicated by thin layer chromatography. The pure acyclovir diacetate (5) was obtained by simply washing with chloroform in good yield. It was surprising to learn that the ratio of N9 /N7 -isomers could be significantly manipulated in this manner.

1. customOn monitoring this reaction by thin layer chromatography, it
2. customproduced N7 -isomer first, which
3. customUnder these condensation conditions, pure N7 -
4. customto give the same equilibrated mixture