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We have discovered a 3-bromo-7-phenoxypyrazolo[1,5-a]pyrimidine intermediate that allows for the direct sequential funtionalization of the 3-position and 7-position of a pyrazolo[1,5-a]pyrimidine scaffold. The intermediate and general method described herein offer an improvement over prior methods, particularly in cases where multiple unique 3-aryl substituents are to be incorporated in conjunction with multiple unique 7-amino substituents.

Recent efforts in our laboratories have resulted in efficient racemic syntheses of isopanepoxydone and panepoxydone, secondary metabolites isolated originally from the basidiomycete Panus conchatus . These synthetic efforts have led us to assign the structure of isopanepoxydone as that of 3 and re-assign the structure of panepoxydone as 2 .

Isothermal titration calorimetry (ITC) is employed to determine the energetics and stoichiometry of binding of HMPA to YbCl3 in THF. The calorimetrically obtained stoichiometry for the trivalent ytterbium/HMPA complex agrees with the previously reported crystal structure.