Various solvents were tested (ACN, THF, DMF and Pyridine, entries 8-11), revealing that DCM provides the best yield (Entry 1). Additionally, the use of molecular sieves slightly increased the yield; however, azeotropic drying of the starting materials with THF three times achieved a similar effect. Ultimately, the use of 10 mol% DIPEA along with DBU (2.5 equiv) proved ideal.