| 摘要 |
<p>An improved process for the preparation of 2'-modified nucleosides and 2'- deoxy-nucleosides, such as, .beta.-L-2'-deoxy-thymidine (LdT), is provided. In particular, the improved process is directed to the synthesis of a 2'- deoxynucleoside that may utilize different starting materials but that proceeds via a chloro-sugar intermediate or via a 2,2'~ anhydro-1-furanosyl- nucleobase intermediate. Where an 2,2'-anhydro-1-furanosyl base intermediate is utilized, a reducing agent, such as Red-Al, and a sequestering agent, suc h as 15-crown-5 ether, that cause an intramolecular displacement reaction and formation of the desired nucleoside product in good yields are employed. An alternative process of the present invention utilizes a 2,2'-anhydro-1- furanosyl base intermediate without a sequestering agent to afford 2'- deoxynucleosides in good yields. The compounds made according to the present invention may be used as intermediates in the preparation of other nucleosid e analogues, or may be used directly as antiviral and/or antineoplastic agents .</p> |
