Asymmetric Synthesis of (1,3-Butadien-2-yl)methanols from Aldehydes via [1-(Silylmethyl)allenyl]methanols

[1-(Silylmethyl)allenyl]methanols 2 were efficiently synthesized from aldehydes and (4-bromobut-2-ynyl)trimethylsilane in the presence of a catalytic amount of CrCl2 and tridentate carbazole ligands The desired compounds were obtained with good yields (43-88%) and enantioselectivities (55-78% ee) Alcohols 2 may be treated with TBAF or 2 M HCI in the case of aliphatic substrates, to provide (1,3-butadien-2-yl)methanols 3 in 43-81% yields This method allows the synthesis of dienes 3 with no regioselectivity problems, and it tolerates a large number of functionalities