O, S or NRPR or where 1, 2 or 3 hydrogen atoms of the heterocycle or where 1, 2 or 3 hydrogen atoms of the 4 5 6 or 7 membered ring are substituted with ORPR, SRPR, N RPR, O Si R, CHO, CHS, CN, NO, OSO H, OPO H, O, S, N OH, CH or a spiro ring an ester, a thioester, a thionoester, a phosphoester, a phosphothioester, a phosphonoester, a phosphiniester, a sulfite ester, a sulfate ester, a sulfoxide, a sulfamate, a sulfonate, a sulfamide, a sulfinamide, a sulfurous diamide, an amide, an amino acid, a peptide, an ether, a thioether, an acyl group, a thioacyl group, a carbonate, a carbamate, an acetal, a thioacetal, a halogen, an optionally substituted alkyl group, an optionally substituted alkenyl group, an optionally substituted alkynyl group, an optionally substituted aryl moiety, an optionally substituted heteroaryl moiety, an optionally substituted monosaccharide, an optionally substituted oligosaccharide, a nucleoside, a nucleotide, an oligonucleotide or a polymer cialis online pharmacy