Methanesulfonic Acid → HCID 20770862, compound

Participants

Reaction Steps

A solution of compound 78A from the preceding step (8.6 g, 32 mmol) in 30 mL of dichloromethane was added dropwise to 30 mL of methanesulfonic acid stirred under N2 at icebath temperature. The mixture was allowed to warn gradually to room temperature. After an hour 200 mL of icewater was cautiously added (vigorous reaction!), then the mixture was partitioned between a total of 300 mL of water and 350–400 mL of dichloro-methane. The organic layer was drawn off and washed with water, then 0.5M aq NaHCO3, and dried over MgSO4. The solvent was removed in vacuo, and the residue dissolved in a minimum of CHCl3/EtOAc (24:1) and passed slowly through a column of silica gel, eluting with several column volumes of the same solvent. The effluent was stripped of solvent in vacuo to leave the title compound as a clear amber syrup, contaminated with the other possible regio-isomer, but of sufficient purity for the next step.

Provenance & Evidence