Phosphoric Acid → HCID 86746933, compound

Participants

Reaction Steps

p-Toluenesulfonic acid (28.5 mg, 0.15 mmol) and 2,2-dimethoxypropane (3.075 ml, 25 mmol) were added to a solution of compound D from Example 1 (3.65 g, 10 mmol) in 30 ml benzene. The solution was refluxed for 30 minutes after which benzene was slowly distilled over a period of 1 hour by which time the volume in the reaction flask had reduced to 10 ml. Fresh portions of p-toluene solfonic acid (28.5 mg, 0.15 mmol), 2,2-dimethoxypropane (6.16 ml, 50 mmol) and benzene (25 ml) and the slow distillation was repeated. The addition and distillation sequence was repeated five more times after which the reaction was judged almost complete by TLC. The reaction mixture was concentrated and the residue (4.5 g) chromatographed (150 g silica gel, 1:1 hexane/ethyl acetate to 2:8:0.1 hexane/ethyl acetate/acetic acid) to yield 3.524 g (87%) pure title A compound and 0.314 g (8.6%) of unreacted starting material, [α]D =-5.8° (c=0.89 CH3OH) which was characterized by MS, 1H NMR, 13C NMR and 31P NMR [23.3 and 20.2 ppm 9:1) w.r.t. H3PO4 =0, external standard 36.5 MHz].

Provenance & Evidence