Similarly, the addition of d4-methanol or d3-MeCN resulted in a significant incorporation of deuterium into product 2a, in line with the reported proton donating abilities of these solvents. Finally, the use of NaBD4 resulted in deuterium incorporation into product 2a to a minor extent, indicating that the borohydride may also serve as a hydrogen source. This route is likely to occur via H/D scrambling or via reduction of in situ formed 3a.