Reaction of aldose derivatives with dimethyl(diazomethyl)phosphonate, generated in situ by methanolysis of dimethyl(1-diazo-2-oxopropyl)phosphonate leads to glyco-1-ynitols derivatives. This synthesis presents two main advantages: it is a one-step synthesis, and tolerates free hydroxyl groups. (C) 2000 Elsevier Science Ltd. All rights reserved.
Fischer Carbene Catalysis of Alkynol Cycloisomerization: Application to the Synthesis of the Altromycin B Disaccharide
作者:BonSuk Koo、Frank E. McDonald
DOI:10.1021/ol070435s
日期:2007.4.1
[reaction: see text] The tungsten-catalyzed cycloisomerization of alkynyl alcohols can be conducted without using photochemistry, using a stable tungsten Fischer carbene as the precatalyst for this transformation. A variety of alkynyl alcohols undergo cycloisomerization under these conditions to provide endocyclic enol ethers of five-, six-, and seven-membered ring sizes. The utility of this method is further
Synthesis of Seven-Membered Ring Glycals via <i>endo</i>-Selective Alkynol Cycloisomerization
作者:Eva Alcázar、Joseph M. Pletcher、Frank E. McDonald
DOI:10.1021/ol0483495
日期:2004.10.1
[reaction: see text] Alkynyldiols 1 undergo cycloisomerization to the corresponding seven-membered cyclic enol ethers 2 under tungsten carbonyl catalysis. This novel transformation proceeds with good yields and virtually complete regioselectivity for all diastereomers of 1, favoring the product 2 resulting from endo-mode cyclization. The unexpected regioselectivity may be dependent on the presence