Disclosed are methods and intermediates for the preparation of 7-(2'-R.sup.1-substituted-.beta.-D-ribofuranosyl)-4-amino-5-(optionally substituted ethyn-1-yl)-pyrrolo[2,3-d]pyrimidine compounds. These compounds are useful in treating viral infections caused by a flaviviridae family virus, such as hepatitis C virus. Such 7-(2'-substituted-.beta.-D-ribofuranosyl)-4-amino-5-(optionally substituted ethyn-1-yl)-pyrrolo[2,3-d]pyrimidine compounds are represented by Formula I as follows: ##STR00001## wherein, each of R.sup.1, R.sup.2, and R.sup.3 are as defined herein.