Catalytic Asymmetric Nozaki-Hiyama Allenylation

Significance

A catalytic asymmetric Nozaki-Hiyama allenylation of alkyl or aryl aldehydes afforded various 2-silylated secondary allenyl alcohols from a terminally silylated propargyl halides. By using a catalytic amount of CrCl₂ and a chiral carbazole tridentate ligand in the presence of excess Mn, the product was obtained in good enantioselectivities and good to excellent yield. The silyl group in the product can be easily removed under standard conditions (TBAF, -78 °C) to afford the corresponding chiral allenyl alcohol in quantitative yield without diminishing the enantio­selectivity.