Selective Transformation of 2,3-Epoxy Alcohols and Related Derivatives. Strategies for Nucleophilic Attack at Carbon-1

In connection with the continuing recent interest in the stereoselective synthesis of epoxy alcohols, a systematic investigation of the bimolecular nucleophilic ring-opening reactions of acyclic 2,3-epoxy alcohols was undertaken. Strategies for nucleophilic attack at C-1 of a 2,3-epoxy alcohol, each of which depends upon the regioselective ring-opening of a 1,2-epoxy 3-ol, were explored. Under Payne rearrangement conditions, t-BuSNa was found to react with 2,3-epoxy alcohols to afford 1-tert-butylthio 2,3-diols. These diols can be readily converted to 1,2-epoxy 3-ols via S-alkylation followed by treatment with base. Alternatively, 1,2-epoxy 3-ols can be prepared from 2,3-epoxy alcohols by sulfonylation and acidic hydrolysis followed by ring-closure of the diol sulfonate intermediate. Dialkylamines were also found to react selectively with 2,3-epoxy alcohols under Payne rearrangement conditions to afford 1-amino 2,3-diols.