Facile High-Yield Synthesis of Singly Isomeric 2', 3'–o–Alkoxymethylidene Adenosine

Abstract

Of all the protecting groups developed for the cis–2',3'–diol system of nucleosides, among the most useful are the 2;3'-O-alkoxymethylldene derivatives in terms of ease of preparation, stability on storage, inertness to many reaction conditions and ease of removal. These compounds, first reported by Zemlicka,¹ have been prepared by transesterification of trimethyl or triethyl orthoformate and nucleosides with anhydrous HCl in dimethylformamide,² with trichloroacetic acid in dioxane,³ and with toluene sulfonic acid in excess orthoformate as solvent.⁴ In the course of our synthetic studies on nucleotide derivatives it became desirable to improve the large scale preparation for this class of compounds. We here report the facile preparation of derivatives of adenosine, 1.