Eisink Niek N H M, Witte Martin D, Minnaard Adriaan J
Stratingh Institute for Chemistry, University of Groningen , Nijenborgh 7, 9747 AG, Groningen, The Netherlands.
ACS Catal. 2017 Feb 3;7(2):1438-1445. doi: 10.1021/acscatal.6b03459. Epub 2017 Jan 18.
Palladium/neocuproine catalyzed oxidation of glucosides shows an excellent selectivity for the C3-OH, but in mannosides and galactosides, unselective oxidation was initially observed. For further application in more-complex (oligo)saccharides, a better understanding of the reaction, in terms of selectivity and reactivity, is required. Therefore, a panel of different glycosides was synthesized, subjected to palladium/neocuproine catalyzed oxidation and subsequently analyzed by qNMR. Surprisingly, all studied glucosides, mannosides, galactosides, and xylosides show selective oxidation of the C3-OH. However, subsequent reaction of the resulting ketone moiety is the main culprit for side product formation. Measures are reported to suppress these side reactions. The observed differences in reaction rate, glucosides being the most rapidly oxidized, may be exploited for the selective oxidation of complex oligosaccharides.
钯/新亚铜试剂催化的糖苷氧化反应对C3-OH具有优异的选择性，但在甘露糖苷和半乳糖苷中，最初观察到的是无选择性氧化。为了在更复杂的（寡）糖中进一步应用，需要从选择性和反应性方面更好地理解该反应。因此，合成了一组不同的糖苷，使其进行钯/新亚铜试剂催化的氧化反应，随后通过定量核磁共振（qNMR）进行分析。令人惊讶的是，所有研究的葡萄糖苷、甘露糖苷、半乳糖苷和木糖苷均显示出C3-OH的选择性氧化。然而，所得酮部分的后续反应是形成副产物的主要原因。本文报道了抑制这些副反应的措施。观察到的反应速率差异（葡萄糖苷氧化最快）可用于复杂寡糖的选择性氧化。
