(R)-2-Methyl-CBS-oxazaborolidine → HCID 54202943, compound

Participants

Reaction Steps

A solution of 2.7 mL of 1.0 M (R)-2-methyl-CBS-oxazaborolidine solution in toluene in 4 mL of CH2Cl2 at −25 °C. was treated with 1.4 mL of 2.0 M borane methyl sulfide complex in THF and stirred cold for 10 min. A solution of 501 mg (2.66 mmol) of cyclopentylmethylene phenyl ketone (from Step B) in 2 mL of CH2Cl2 was added over 25 min and the resulting mixture was stirred cold for an additional 45 min. The reaction was quenched by pouring it into cold (−25° C.) MeOH. The quenched reaction was warmed to rt and stirred for 45 min until gas evolution ceased. The mixture was concentrated and the residue dissolved in 20 mL of MeOH and concentrated again. Flash chromatography on silica gel using 17:3 v/v hexanes/EtOAc afforded 413 mg (81%) of the title compound: RF: 0.53 (4:1 v/v hexanes/ EtOAc); 1H NMR (300 MHz): δ1.10-1.17 (m, 2H), 1.47-1.89 (m, 9H), 4.69 (m, 1H), 7.25-7.35 (m, 5H).

Provenance & Evidence