Toluene → 5-((1R)-2-bromo-1-hydroxyethyl)-8-phenylmethoxy-1H-quinolin-2-one

Participants

Reaction Conditions

Reaction Steps

A dry 5 liter flask equipped with a mechanical stirrer, thermometer, addition funnel and refluxing condenser was charged with 5-Bromoacetyl-8-benzyloxycarbostyril (100 gms/0.268 moles) and dry THF (1.2 liter) under argon. A solution of (R)-tetrahydro-1-methyl-3,3-diphenyl-(1H,3H)-pyrrolo[1,2-c][1,3,2]-oxazaborolidine catalyst in toluene (43 ml/0.388 moles) was added and reaction mass was chilled to 0-2° C. Then, 1M solution of borane-methyl sulfide (32.42 ml/0.3417 moles) in THF (342 ml) was added in 3 hours while maintaining temperature at 0-2° C. The reaction was stirred for another 15-20 minutes at same temperature. The reaction mass was quenched by addition of methanol (171 ml) in 15-20 minutes. The temperature of resulting solution was raised to 25-30° C. and concentrated to a volume of 500 ml under vacuum at 50° C. To this concentrate was added a mixture of water (1.45 liters) and concentrated HCl (74 ml) in 10-15 minutes. The resulting suspension was stirred for 30 minutes at 25° C. The solid 8-benzyloxy-5-[(R)-(2-bromo-1-hydroxyethyl)]-carbostyril obtained was isolated by filtration and washed with water till neutral pH, dried under vacuum at 60-65° C. for 12-14 hours. Yield-70-73 gms.

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