反应详情

The compound prepared in Example 91 (6.0 g, 0.012 mol), toluene (15 g, 0.16 mol), methanol (100 g, 3.1 mol) and concentrated sulfuric acid (0.4 g, 0.004 mol) are added to a reaction flask and heated to reflux. After eight hours at reflux, the solvents are removed by distillation and the residue is dissolved in 200 g of toluene. The solution is then passed through an absorbent (silica gel) to remove residual acid. The toluene is distilled off and the residue is twice recrystallized from methanol. The title compound is obtained in a yield of 4.9 g as a light yellow powder melting at 93-104° C. whose structure is consistent with 1Hnmr and mass spectrometric analyses.

1. temperatureheated to reflux
2. temperatureAfter eight hours at reflux
3. customthe solvents are removed by distillation
4. dissolutionthe residue is dissolved in 200 g of toluene
5. customto remove residual acid
6. distillationThe toluene is distilled off
7. customthe residue is twice recrystallized from methanol