C-Functionalization of 9-deazapurines by cross-coupling reactions

C-Functionalization of pyrrolo3,2-d]pyrimidine scaffold in positions 2, 4, and 7 using cross-coupling reactions was performed. Thus, 2-(5-(benzyloxymethyl)-2,4-dichloro-5H-pyrrolo3,2-d]pyrimidin-7-yl)ethanol, a versatile synthetic precursor for 9-deazapurines and 4,6-diazaindoles, was prepared by vinylation of the corresponding iodide followed by hydroboration of the double bond. A synthesis of 9-(1,2-dihydroxyethyl)-9-deazaadenine, a 9-deaza-1′-nor congener to antiviral DHPA, was developed. In addition, an abnormal regioselectivity in methylalumination of the terminal triple bond in position 7 of the pyrrolo3,2-d]pyrimidine scaffold leading to a transformation into (Z)-prop-1-enyl was observed.