3-Buten-2-one,4-(4-bromophenyl)- → HCID 68433579, compound

Participants

Reaction Conditions

Reaction Steps

To 5.55 g (24.7 mmol) of the ketone from Step A dissolved in 100 mL of toluene was added 3.7 mL (3.7 mmol, 1M in toluene) of (R)-2-methyl-CBS-oxazaborolidine catalyst and the resultant mixture was stirred at ambient temperature for 15 min. The mixture was cooled to −78° C. and 4.0 mL (37.1 mmol) of catecholborane in 30 mL of toluene was added dropwise over 30 minutes. After the addition, the slurry was stirred at −78° C. for 60 min while slowly turning homogeneous. The solution was then stirred at −78° C. an additional 4 hours (reaction time varies from 4–24 hours) until TLC revealed complete disappearance of starting material. Next, the reaction mixture was diluted with 100 mL of water and the resultant mixture was extracted with three 100-mL portions of diethyl ether. The organic phases were then combined and washed with two 100-mL portions of 1 N NaOH aqueous solution, two 100 mL portions of 5% hydrochloric acid solution, 100-mL portions of saturated aqueous brine, dried over magnesium sulfate, filtered, and evaporated in vacuo to yield the crude waxy solid. The crude material was then purified by flash chromatography on a Biotage® system (silica gel, 0 to 20% ethyl acetate/hexanes gradient) to give the alcohol as a colorless crystalline solid. This compound was recrystallized in hexanes to yield the alcohol as colorless crystals (96% ee by Mosher ester analysis). LC/MS 209.0 (M−H2O+1), 211.0 (M−H2O+3).

Provenance & Evidence