Gurram V.,GVK Biosciences Pvt. Ltd. 28A |
Gurram V.,Jawaharlal Nehru University |
Pottabathini N.,GVK Biosciences Pvt. Ltd. 28A |
Garlapati R.,GVK Biosciences Pvt. Ltd. 28A |
And 3 more authors.
Chemistry - An Asian Journal | Year: 2012
Reaction conditions for the C-C cross-coupling of O 6-alkyl-2- bromo- and 2-chloroinosine derivatives with aryl-, hetaryl-, and alkylboronic acids were studied. Optimization experiments with silyl-protected 2-bromo-O 6-methylinosine led to the identification of [PdCl 2(dcpf)]/K 3PO 4 in 1,4-dioxane as the best conditions for these reactions (dcpf=1,1'-bis(dicyclohexylphosphino)ferrocene). Attempted O 6-demethylation, as well as the replacement of the C-6 methoxy group by amines, was unsuccessful, which led to the consideration of Pd-cleavable groups such that C-C cross-coupling and O 6-deprotection could be accomplished in a single step. Thus, inosine 2-chloro-O 6-allylinosine was chosen as the substrate and, after re-evaluation of the cross-coupling conditions with 2-chloro-O 6-methylinosine as a model substrate, one-step C-C cross-coupling/deprotection reactions were performed with the O 6-allyl analogue. These reactions are the first such examples of a one-pot procedure for the modification and deprotection of purine nucleosides under C-C cross-coupling conditions. © 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.