A Facile Synthesis of 6-Aryl-5-cyano-1-(β-d-pyranosyl or β-d-furanosyl)-2-thiocytosines
摘要:
The treatment of a piperidinium salt of 6-aryl-5-cyano-2-thiouracil with an O-peracetyl-alpha -D-pyranosyl bromide produces a mixture of N1-(beta -D-pyranosyl)-2-thiouracil and its N1,S-2-disubstituted analog. By contrast, the reaction of a silyl derivative of the 2-thiouracil with an O-pcracetyl-beta -D-pyranose furnishes the mononucleoside selectively. Both the mononucleoside/dinucleoside mixture and pure mononucleoside undergo ammonolysis under mild conditions to give the P-D-nucleoside of 6-aryl-5-cyano-2-thiocytosine. The silyl method also provides an easy access to beta -D-ribosyl nucleosides. (C) 2000 Elsevier Science Ltd. All rights reserved.
The first direct ammonolysis of 2-thiouracil nucleosides to 2-thiocytosine nucleosides
摘要:
Sugar-peracetylated 1-(beta-D-glucopyranosyl)-, 1-(beta-D-galactopyranosyl)-, and 1-(beta-D-xylopyranosyl)-6-aryl-5-cyano-2-thiouracils 2-4 and the corresponding 1-pyranosyl-2-(pyranosylthio)pyrimidines 5-7 undergo efficient ammonolysis (NH3/MeOH, 0-->23 degrees C, 16 h) to give the corresponding 1-(beta-D-pyranosyl)-6-aryl-5-cyano-2-thiocytosines. (C) 2000 Elsevier Science Ltd. All rights reserved.