Chemoselective Cross Metathesis of Bishomoallylic Alcohols: Rapid Access to Fragment A of the Cryptophycins
摘要:
The racemic or enantioselective allylation of in situ formed beta,gamma-unsaturated aldehydes provides efficient access to bishomoallylic alcohols from readily available 2-vinyloxiranes. These products, when subjected to modified Grubbs cross metathesis conditions, afforded terminally homologated products in moderate to good yields with high E selectivity and without degradation of the enantiomeric excess. The compounds obtained through this two-step sequence yield fragments of an important and pharmacologically active family of cryptophycins.
A direct approach to amines with remote stereocentres by enantioselective CuH-catalysed reductive relay hydroamination
作者:Shaolin Zhu、Nootaree Niljianskul、Stephen L. Buchwald
DOI:10.1038/nchem.2418
日期:2016.2
elements in many pharmaceutical agents and natural products. However, previously reported methods to prepare these compounds in an enantioselective manner are indirect and require multistep synthesis. Here, we report a copper-hydride-catalysed, enantioselectivesynthesis of γ- or δ-chiral amines from readily available allylic alcohols, esters and ethers using a reductive relay hydroamination strategy (a
Rhodium-Catalyzed Ring Opening of Vinyl Epoxides with Alcohols and Aromatic Amines
作者:Keith Fagnou、Mark Lautens
DOI:10.1021/ol0060782
日期:2000.7.1
[Rh(CO)(2)Cl](2) is an effective catalyst for the ringopening of vinyl epoxides with alcohols and aromatic amines under neutral conditions at room temperature. The reaction occurs with excellent diastereo- and regioselectivity (>20:1) giving the trans-1,2-amino alcohols or alkoxy alcohols for a wide range of substrates. The regio- and stereochemistry of these reactions is complementary to that typically