2,3-Dichloro-5,6-dicyano-1,4-benzoquinone → 3-((3R,4S)-3-{[tert-butyl(dimethyl)silyl]oxy}tetrahydro-2H-pyran-4-yl)-6-{[6-(hydroxymethyl)pyridine-3-yl]methyl}benzo[h]quinazolin-4(3H)-one

Participants

Reaction Steps

To a solution of methyl 5-{[3-((3R,4S)-3-{[tert-butyl(dimethyl)silyl]oxy}tetrahydro-2H-pyran-4-yl)-4-oxo-3,4-dihydrobenzo[h]quinazolin-6-yl]methyl}pyridine-2-carboxylate (see Example 20, 0.250 g, 0.447 mmol) in 5 mL of ethanol was added sodium borohydride (0.034 g, 0.89 mmol). After 15 h, additional sodium borohydride (0.050 g, 1.32 mmol) was added. After 24 h, the mixture was treated with saturated aqueous ammonium chloride and extracted 2× with dichloromethane. The combined organic fractions were dried over sodium sulfate, filtered, and concentrated in vacuo. To a solution of the residue in 3 mL of chloroform was added 2,3-dichloro-5,6-dicyanobenzoquinone (0.101 g, 0.447 mmol). After 15 min, the mixture was concentrated in vacuo and the residue was purified via silica gel chromatography, eluting with 0-5% methanol in dichloromethane to provide 3-((3R,4S)-3-{[tert-butyl(dimethyl)silyl]oxy}tetrahydro-2H-pyran-4-yl)-6-{[6-(hydroxymethyl)pyridine-3-yl]methyl}benzo[h]quinazolin-4(3H)-one that gave proton NMR spectra consistent with theory and a mass ion (ES+) of 532.0 for [M+H]+.

Provenance & Evidence