| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1385481 | Carbohydrate Research | 2007 | 9 Pages |
Kochetkov’s extensive investigations of glycosyl orthoester and their analogs as glycosyl donors revealed that the alkyl derivatives were plagued by competition between the departing alcohol and the incoming acceptor. n-Pentenyl orthoesters (NPOEs) obviate competition by sequestering the departing pentenyl alcohol as a 2-halomethyl tetrahydrofuran. Exquisitely regioselective glycosidations of diol acceptors can be carried out with NPOEs triggered specifically with Yb(OTf)3/NIS. However with Sc(OTf)3, double glycosidation is the major reaction. manno, gluco and galacto NPOEs have been investigated. The latter two, which require a different experimental procedure for the manno counterpart, also give an excellent regioselectivity with Yb(OTf)3, but the yields are much lower than with manno.
Graphical abstractMannosidyl diols can be regio and chemoselectively glycosidated in high yields with manno, gluco and galacto n-pentenyl orthoesters under the agency of ytterbium triflate and N-iodosuccinimide.Figure optionsDownload full-size imageDownload as PowerPoint slide
