2-Ene-1,4-diols by dimerization of terminal epoxides using hindered lithium amides

Reaction of hindered lithium amides with readily available (enantiopure) terminal epoxides gives 2-ene-1,4-diols via carbenoid dimerization of the corresponding ct-lithiated epoxides. D-Mannitol and D-iditol were synthesized using this method in three steps from (S)-tritylglycidyl ether.