Alternatively, a compound of formula (I) can react with an alkynyl (e.g., a compound of the formula L′-X1a where L′ is a precursor of L and X1a has been defined above) to form an intermediate, which can further react with a compound of the formula R1—X3—Y—X2-L″ to form a compound of formula (I). As an example, 6-bromo-2-furan-2-yl-[1,2,4]triazolo[1,5-a]pyrazin-8-ylamine can react with prop-2-yn-1-ol to form 3-(8-amino-2-furan-2-yl-[1,2,4]triazolo[1,5-a]pyrazin-6-yl)-prop-2-1-ol, which can then react with phenol in the presence of triphenyl phosphine and diisopropyl azodicarboxylate to form 2-furan-2-yl-6-(3-phenoxy-prop-1-ynyl)-[1,2,4]triazolo[1,5-a]pyrazin-8-ylamine, a compound of formula (I). See, e.g., Example 22 below.
