Synthesis 2011(15): 2483-2489  
DOI: 10.1055/s-0030-1260090
PAPER
© Georg Thieme Verlag Stuttgart ˙ New York

N 6-Acetyl-2′,3′,5′-tri-O-acetyladenosine; A Convenient, ‘Missed Out’ Substrate for Regioselective N6-Alkylations

Vitali I. Tararov, Svetlana V. Kolyachkina, Cyril S. Alexeev, Sergey N. Mikhailov*
Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Vavilov str. 32, Moscow 119991, Russian Federation
Fax: +7(499)1351405; e-Mail: smikh@eimb.ru;
Further Information

Publication History

Received 15 April 2011
Publication Date:
28 June 2011 (online)

Abstract

A simple and efficient route to N 6-acetyl-2′,3′,5′-tri-O-acetyladenosine (1) was developed based on selective N-deacetylation of pentaacetylated adenosine 2 with methanol at room temperature in the presence of imidazole. Preparative synthesis of 1 was elaborated utilizing a crude mixture of 2 and 1 which is produced by reaction of adenosine with acetic anhydride in pyridine at elevated temperatures. The total yield of 1 was 80-85% starting with adenosine. It was shown that 1 is a convenient substrate for selective N6-alkylations. The study revealed the same regioselectivity in base-promoted reactions of 1 with activated alkyl halides and Mitsunobu reactions of 1 with alcohols. A series of N 6-alkyladenosines 5a-f were prepared. Cytokinins 6b,d,e were prepared by enzymatic transformation of parent nucleoside derivatives 5b,d,e using a combination of nucleoside phosphorylase and alkaline phosphatase.