Metal-Free, Aerobic Dioxygenation of Alkenes Using Hydroxamic Acids
作者:Valerie A. Schmidt、Erik J. Alexanian
DOI:10.1002/anie.201000843
日期:2010.6.14
One dioxygenation please, hold the metal: In the presence of either oxygen or air as the sole oxidant and external oxygen atom source, a variety of unsaturated hydroxamicacids afford cyclic hydroxamates that are readily converted into 1,2‐diols, with the potential for high levels of reaction stereocontrol.
A Radical Version of the Bromo- and the Iodocyclization of Bis(homoallylic) Alcohols— The Synthesis of Halogenated Tetrahydrofurans by Stereoselective Alkoxyl Radical Ring Closures
A new synthesis of bromo- and iodomethyl-substituted tetrahydrofurans has been devised. The sequence starts with the conversion of aryl-functionalized bis(homoallylic) alcohols 1 into N-alkenoxythiazole-2(3H)-thiones 6 or pyridine-2(1H)-thiones 7. When photolyzed in the presence of appropriate trapping reagents, thiones 6 and 7 efficiently liberated substituted 4-penten-1-oxyl radicals 2, which underwent
ABSTRACT A protocol for one-pot Claisenrearrangement with n-butyl vinyl ether is described. Upon heating allylic alcohols with excess n-butyl vinyl ether with catalytic amount of Hg(OAc)2 and NaOAc, Claisenrearrangement takes place through in situ formation of the requisite allyl vinyl ether.
Enantioselective Claisen Rearrangements with a Hydrogen-Bond Donor Catalyst
作者:Christopher Uyeda、Eric N. Jacobsen
DOI:10.1021/ja803370x
日期:2008.7.1
m ion associated with the noncoordinating BArF counterion is shown to be an effective catalyst for the [3,3]-sigmatropic rearrangement of a variety of substitutedallylvinylethers. Highly enantioselective catalytic Claisenrearrangements of ester-substituted allylvinylethers are then documented using a new C2-symmetric guanidinium ion derivative.
Vanadium(V) complexes 4 have been prepared from tridentate Schiff-base ligands 3 and VO(OEt)3. All vanadium(V) compounds were characterized (IR, UV/Vis, and 51V NMR spectroscopy, and in selected examples by X-ray diffraction analysis) and were applied as oxidation catalysts for the stereoselective synthesis of functionalized tetrahydrofurans 2 starting from substituted bis(homoallylic) alcohols 1 (mono-