Triphenylphosphine → (2S)-1-bromo-3-(tert-butoxy)-2-methylpropane

Participants

Reaction Steps

A solution of 25.8 g. (0.176 mole) of (R)-(+)-3-tert. butoxy-2-methyl-1-propanol and 50.5 g. (0.193 mole) of triphenylphosphine in 105 ml. of CH2Cl2 was stirred while 32.8 g. (0.184 mole) of N-bromosuccinimide was added in portions, keeping the temperature below 30° C. with occasional ice bath cooling. The resulting solution was stirred at room temperature for one hour then most of the solvent was distilled under a water aspirator pressure using a Vigreaux column. The product was distilled from the residue using a short distilling head giving 0.7 g. of forerun b.p. 58°-62° C. (23 mm Hg) and then the main fraction (31.1 g.) b.p. 62°-69° C. (14-18 mm Hg). The total distillate (31.8 g.) was chromatographed on 450 g. of silica gel. Elution with 19:1 parts by volume and 9:1 parts by volume hexane-ether yielded the pure (S)-(+)-3-tert. butoxy-2-methyl- 1-bromopropane which was distilled giving 26 g. (70.6%) of colorless liquid, b.p. 71° C. (16 mm Hg); [α]25D+23.32° (c 4.23, C6H6).

Provenance & Evidence