Stereoselective Synthesis of 2-Methyl-3-butene-1,2-diols

Significance

A new stereoselective synthesis of both syn and anti isomers of 2-methyl-3-butene-1,2-diols was developed. 1-Methylallenylborate hydroboration at room temperature generates kinetic intermediate (Z)-allylborane. It isomerizes to the thermodynamically more stable (E)-isomer at 85 ˚C. The following aldehyde allylboration generates target diols in good yields and stereoselectivities.