Low-Barrier Pathway for<i>endo</i>-Cleavage Induced Anomerization of Pyranosides with<i>N</i>-Benzyl-2,3-<i>trans</i>-oxazolidinone Groups
作者:Hiroko Satoh、Jürg Hutter、Hans Peter Lüthi、Shino Manabe、Kazuyuki Ishii、Yukishige Ito
DOI:10.1002/ejoc.200801140
日期:2009.3
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
即使在弱路易斯酸存在下,具有 N-苄基-2,3-反式-恶唑烷酮的吡喃糖苷也会发生从 β 型到 α 型的异构化。获得了在异构化反应中内裂,即吡喃-氧和异头碳原子之间的键断裂的实验证据。通过量子力学计算研究了这种意外现象,该计算发现异构化和非异构化底物之间的过渡态存在明显差异。计算表明,BF3 诱导内切,然后旋转 C1-C2 键,通过较低能量的过渡态产生 α 形式。(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)