Triphenylphosphine → HCID 25159011, compound

Participants

Reaction Steps

(7R)-2-Amino-8-[(4-methoxy-3,5-dimethylpyridin-2-yl)methyl]-7-methyl-7,8-dihydropteridin-6(5H)-one (Example 2[2])(60 mg, 0.18 mmol) was suspended in THF (10 mL) and the 3-methoxy-1-propanol (70 μL, 0.73 mmol) was added, followed by triphenylphosphine (192 mg, 0.73 mmol) and DIAD (144 μL, 0.73 mmol). The mixture was stirred at room temperature for 2 hours. A further quantity of triphenylphosphine (192 mg, 0.73 mmol) and DIAD (144 μL, 0.73 mmol) were added and stirring continued for 2 hours. A further quantity of triphenylphosphine (192 mg, 0.73 mmol) and DIAD (144 μL, 0.73 mmol) were added and stirring continued overnight. TLC and LCMS analysis showed complete reaction; the mixture was diluted with methanol (5 mL) and loaded onto an SCX-2 column which had been equilibrated with 30% methanol in DCM. The column was eluted with 30% methanol in DCM to remove impurities, then with 30% (3M NH3 in methanol) in DCM to elute the product. The appropriate fractions were concentrated in vacuo; the residue (about 40 mg) was found to be a mixture of N- and O-alkylated products. The sample was dissolved in methanol (5 mL) and 6N HCl (2 mL) was added. The mixture was stirred at room temperature for 2 hours. LCMS showed complete hydrolysis of the O-alkylated material; the desired N-alkylated material was unchanged. The mixture was concentrated in vacuo and the residue was purified by chromatography, eluting with 0 to 5% (10:1 methanol/concentrated NH3 (aqueous)) in DCM. The appropriate fractions were concentrated under reduced pressure to give the title compound as a pale yellow gum (20 mg, 27%); 1H NMR spectrum (400 MHz, CDCl3) δ 1.36 (3H, d), 1.89 (2H, ddt), 2.17 (3H, s), 2.25 (3H, s), 3.39 (2H, td), 3.75 (3H, s), 3.81 (1H, dd), 3.97 (1H, dd), 4.03 (1H, q), 4.09 (1H, d), 4.67 (2H, s), 5.70 (1H, d), 7.70 (1H, s), 8.18 (1H, s); Mass spectrum: (M+H) 401.

Provenance & Evidence