(S)-(−)-2-tert-butyl-3-methylene-oxirane: Synthesis and hydroboration of a chiral allene oxide

The chiral allene oxide, (S)-(-)-2-tert-butyl-3-methylene-oxirane 12 ((S)-(-)-1-tert-butylallene oxide) was prepared in a moderate yield and in high enantiomeric excess by a three-step conversion starting from 4,4-dimethyl-2-pentyn-1-ol 6. The procedure was comprised of hydrostannylation, Sharpless epoxidation and deoxystannylation. The chiral allene oxide 12 has moderate stability for identification and characterization and undergoes hydroboration to afford a chiral diol, (R)4,4-dimethylpentane-1,3-diol 15.