Smith Glenn, Pedersen Steven F., Leary Julie A.
Department of Chemistry, University of California, Berkeley, California 94720.
J Org Chem. 1997 Apr 4;62(7):2152-2154. doi: 10.1021/jo9622789.
Octahedral nickel(II)-N-glycoside complexes of glucose, galactose, mannose, and talose were synthesized and analyzed by electrospray ionization (ESI). A resulting tricoordinate species generated from the octahedral complex was subjected to collision-induced dissociation. A highly stereoselective dissociation pathway involving beta-hydrogen elimination and cross-ring cleavages was observed in complexes possessing equatorial C-2 substituents. (2)H- and (13)C-labeling experiments indicate that the hydrogen on C-2 and a labile proton are involved in the beta-hydrogen elimination. Additionally, C-4, C-5, and C-6 are shown to be lost from the monosaccharide as a result of the cross-ring cleavages. A mechanism is postulated to explain the stereoselectivity of this dissociation.
合成了葡萄糖、半乳糖、甘露糖和塔罗糖的八面体镍（II）-N-糖苷配合物，并通过电喷雾电离（ESI）进行分析。由八面体配合物产生的三配位物种进行了碰撞诱导解离。在具有赤道C-2取代基的配合物中观察到了一条涉及β-氢消除和跨环裂解的高度立体选择性解离途径。（2）H和（13）C标记实验表明，C-2上的氢和一个不稳定质子参与了β-氢消除。此外，由于跨环裂解，单糖中的C-4、C-5和C-6会丢失。提出了一种机制来解释这种解离的立体选择性。
