Pyranosides with N-benzyl-2,3-trans-oxazolidinone undergo anomerization from the β form to the α form even in the presence of a weak Lewis acid. Experimental evidence for endo-cleavage, the breaking of the bond between the pyran-oxygen and anomeric carbon atoms, in the anomerization reactions was obtained. This unexpected phenomenon was investigated by quantum mechanical calculations, which found clear differences in the transition states between anomerized and non-anomerized substrates. The computations suggest that BF 3 induces endo-cleavage followed by rotation of the C1-C2 bond to give the α form via lower-energy transition states.
- Density functional calculations
- Protecting groups
- Transition states
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Organic Chemistry