摘要:
Intramolecular acyl transfer of (R)-5-(alpha-methylbenzyl)amino-1,3-dioxan-2-one (2) by treatment with DBU in CD2Cl2, CDCl3, C6D6, CD3CN, CD3NO2, DMSO-d(6), DMF, THF-d(8), (PrOH)-Pr-i, and (BuOH)-Bu-t at room temperature afforded (4S,alpha R)-4-hydroxymethyl-3-alpha-methyl-benzyl-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, (PrCO2H)-Pr-i, (BuCO2H)-Bu-t, 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-d(8). (C) 2007 Elsevier Ltd. All rights reserved.