Ketalised 3,4-dihydroxybutyllithiums: New intermediates to transfer four- carbon diol functionality to electrophilic reagents

Article abstract of DOI:10.1016/0040-4020(96)00392-4

The reaction of ketalised 1-chlorobutane-3,4-diol 1a,b with lithium powder and a catalytic amount of 4,4'-di-tert-butylbiphenyl (DTBB, 4 mol %) in the presence of an electrophile [Pr(i)CHO, Bu(t)CHO, PhCHO, Pr(n)COMe, (CH₂)₅CO] at -78°C in THF (Method A: Barbier-type conditions) leads, after hydrolysis, to the formation of the corresponding ketalised reaction products 2aa-bf. Alternatively, the reaction can be carried out in a two-step process (Method B), which implies first a DTBB-catalysed lithiation folowed by reaction with an electrophile [Me₃SiCl, Pr(i)CHO, Bu(t)CHO, PhCHO, Me₂CO, Et₂CO,Pr(n)COMe, (CH₂)₅CO, PhCOMe] both steps being performed at -78°C. When the starting materials are chiral, this methodology allows the preparation of chiral protected di or triols in a nondiastereoselective manner.