Pyridine → HCID 22117060, compound

Participants

Reaction Steps

A suspended mixture of 2-tert-butyldimethylsiloxy-9-trimethylsilyl-9-xanthene-carboxylic acid phenyl ester, 6 (570 mg, 1.13 mmole), in CH3CN (10 ml) and pyridine (2 ml) became a clear yellow solution after a brief stirring at room temperature. The mixture was treated with 20 drops of 48% HF from a pipette and stirred for 3 hrs at room temperature. The reaction mixture was quenched with dilute HCL solution, followed by two extractions with 30% EtOAc-hexanes. The combined organic layers were washed with water, dried over anhydrous Na2SO4 and concentrated. The residue was dissolved in a minimum amount of 2% MeOH-CH2Cl2 and chromatographed on a silica gel column, eluting with CH2Cl2 to 2% MeOH-CH2Cl2. The relatively clean fractions were pooled and concentrated. The impure yellow product was further purified by trituration first with 5% EtOAc-hexanes followed by hexanes, yielding pure phenyl 2-hydroxy-9H-9-xanthene-carboxylate 7 ((173.5 mg, 48.3%) as a slightly yellow solid: mp 182-184° C.; 1H NMR (DMSO-d6): delta 7.33-7.40 (3H, m), 7.24 (1H, m), 7.13-7.17 (2H, m), 7.04 (1H, d, J=8.8 Hz), 6.95-6.98 (2H, m), 6.90 (1H, d, J=2.6 Hz), 6.78 (1H, dd, J=8.8, 2.6 Hz) and 5.40 (1H, s).

Provenance & Evidence