Lithium borohydride → HCID 66952775, compound

Participants

Reaction Steps

To a solution of 261B (270 mg, 0.75 mmol) was added LiBH4 (15.5 mg, 0.71 mmol). The mixture was heated to reflux for 1.0 hr. HPLC showed still some starting material remaining. More LiBH4 (15.5 mg, 0.71 mmol) was added, and the mixture was heated for another 2.0 hrs. After cooling to room temperature, ice water was added, and the mixture was concentrated in vacuo to remove the THF. The aqueous residue was extracted with EtOAc (×3) and the combined extracts were dried (Na2SO4), and concentrated in vacuo. The residue was taken into 2 mL of CH2Cl2 and 2 mL of TFA was added. The mixture was stirred at room temperature for 30 min. The mixture was concentrated in vacuo, followed by drying under high vacuum overnight to afford 261C as an oil. It had an analytical HPLC retention time=0.590 min. (Chromolith SpeedROD column 4.5×50 mm, 10–90% aqueous methanol containing 0.1% TFA over 4 min, 4 mL/min, monitoring at 220 nm) and a LC/MS M++1=235. This material was used directly in the next reaction step without further purification.

Provenance & Evidence