Syntheses of 2,5-disubstituted dihydrofurans from γ-substituted chiral allenamides

ORGN 127

Matthew E Petersen, petersen@chem.umn.edu and Richard Hsung, hsung@chem.umn.edu. Department of Chemistry, Smith Hall, University of Minnesota, 207 Pleasant St SE, Minneapolis, MN 55455-0431
In recent years, allenamides have emerged as a useful functional group in organic synthesis. In our own work, we encountered the need for accessing γ-substituted chiral allenamides that could be used for new synthetic methodologies. Here, we report a new way to access 2,5-disubstituted dihydrofurans, which serve as a template for RNA ribose sugars.

Utilizing Seebach's protocol, the TMS protected N-propargyl imidazolidinone was converted to the corresponding allenyl alcohol in high diastereomeric ratios. Cyclization using PPTS or TBAF afforded the 2,5-disubstituted dihydrofurans, which can be functionalized further using hydrogenation, dihydroxylation, and lewis acid mediated removal of the auxillary.