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 min. 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 h (reaction time varies from 4-24 h) 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+3), 211.0 (M-H2O+3).

Provenance & Evidence