反应详情

The starting material, 2-chloroadenosine of the formula (II) used in the above Process 1 can be obtained in high yield from 6-chloroguanosine or a 2',3',5'-triacyl-6-chloroguanosine as disclosed in Japanese Patent Application OPI No. 48,496/1973. That is, 6-chloroguanosine or a 2',3',5'-triacyl-6-chloroguanosine, e.g., 2',3',5'-triacetyl-6-chloroguanosine, is first reacted with sodium nitrite and hydrochloric acid in ice-water and thereafter the reaction mixture is neutralized with, for example, aqueous ammonia. The resulting reaction mixture is then extracted with a solvent such as methylene chloride and the extract containing 2,6-dichloropurine riboside is treated without isolation of the riboside, with a methanolic solution saturated with anhydrous ammonia gas and the mixture is allowed to react at a temperature of about 100°C for about 5 hours in a sealed tube to obtain the desired 2-chloroadenosine of the formula (II) in about 60% yield. The preparation of the starting material of the formula (II) will be hereinafter described in greater detail in Reference Example 1.

1. customThe resulting reaction mixture
2. extractionis then extracted with a solvent such as methylene chloride
3. additionthe extract containing 2,6-dichloropurine riboside
4. additionis treated without isolation of the riboside, with a methanolic solution saturated with anhydrous ammonia gas
5. customto react at a temperature of about 100°C for about 5 hours in a sealed tube