new chiral β-hydroxy amide ligands were synthesized via the reaction of benzyl chloride and aminoalcohols derived from l-tyrosine. The titanium(IV) complex of chiral ligand 8b was found to be an effective catalyst for the asymmetric alkynylation of aliphatic, vinyl and aromatic aldehydes. The propargyl alcohols were obtained in highly enantiomeric excesses (up to 96% ee) under optimized conditions.
Highly Enantioselective Phenylacetylene Additions to Both Aliphatic and Aromatic Aldehydes
作者:Ge Gao、David Moore、Ru-Gang Xie、Lin Pu
DOI:10.1021/ol026921r
日期:2002.11.1
The readilyavailable and inexpensive BINOL in combination with Ti(O(i)Pr)(4) is found to catalyze the reaction of an alkynylzinc reagent with various types of aldehydes including aliphaticaldehydes, aromaticaldehydes, and other alpha,beta-unsaturated aldehydes to generate chiral propargyl alcohols with 91-99% ee at room temperature. No previous chiral catalysts have exhibited such a broad scope
Access to Highly Functionalized Cyclopentenones via Diastereoselective Pauson–Khand Reaction of Siloxy-Tethered 1,7-Enynes
作者:Austin G. Gallagher、Huan Tian、Osmar A. Torres-Herrera、Shuai Yin、Anxin Xie、Daniel M. Lange、Jerica K. Wilson、Louis G. Mueller、Michael R. Gau、Patrick J. Carroll、Dionicio Martinez-Solorio
DOI:10.1021/acs.orglett.9b03255
日期:2019.11.1
Pauson–Khand reaction (PKR) of siloxy-tethered 1,7-enynes for the synthesis of cyclopentaoxasilinones has been developed. This transformation can be performed on a multigram scale and is characterized by a broad substrate scope, functional group compatibility, and high chemo- and diastereoselectivity. Oxidation of the resulting cyclopentaoxasilinones delivers stereoenriched β-alkylated cyclopentenones, which
A copper-catalyzed formal [1 + 2 + 2]-annulation of alkyne-tethered diazo compounds with pyridines, which affords polycyclic fused indolizines in synthetically useful to good yields under mild reaction conditions, has been reported. This method features the use of an inexpensive copper catalyst and readily available starting materials, broad substrate generality, and operational simplicity. Notably
Neighboring Carbonyl Group Assisted Hydration of Unsymmetrical Aryl Alkynes Overriding Regular Selectivity
作者:Kishor L. Mendhekar、Tapas R. Pradhan、N. Arjunreddy Mallampudi、Debendra K. Mohapatra
DOI:10.1002/ejoc.201900941
日期:2019.9.8
A mild and highly regioselective gold‐catalyzed hydration of γ‐acetoxy aryl alkynes leading to anti‐Markovnikov products by the assistance of a neighboringcarbonylgroup is presented.