Diastereoselective intramolecular acyl transfer of 5-(α-methylbenzyl)amino-1,3-dioxan-2-one to 4-hydroxymethyl-2-oxazolidinones

Intramolecular acyl transfer of (R)-5-(α-methylbenzyl)amino-1,3-dioxan-2-one (2) by treatment with DBU in CD2Cl2, CDCl3, C6D6, CD3CN, CD3NO2, DMSO-d6, DMF, THF-d8, iPrOH, and tBuOH at room temperature afforded (4S,αR)-4-hydroxymethyl-3-α-methylbenzyl-2-oxazolidinone [(4S)-3] in moderate to quantitative yields with 58–94% de via an asymmetric desymmetrization process. Treatment of 2 with DBU and Cs2CO3 in MeOH and EtOH gave (4S)-3 and (4R)-3 without diastereoselectivities. Acidic treatment of 2 using HCO2H, AcOH, EtCO2H, iPrCO2H, tBuCO2H, and C6F5OH in CDCl3 gave (4S)-3 in moderate diastereoselectivities (26–52% de). First-order kinetics were observed in the reaction of 2 to (4S)-3 with DBU in CDCl3 and THF-d8.