Unusual Regioselectivity in the Aldehyde Addition Reactions of Allenyl/Propargyl Zirconium Complexes Derived from γ-(2-Pyridyl)propargyl Ethers: Synthesis of Multisubstituted α-Hydroxyallenes
作者:Guoqin Fan、Xin Xie、Yuanhong Liu、Yuxue Li
DOI:10.1021/om301007z
日期:2013.3.25
different to that of the reactions using propargylic ethers without a pyridyl group reported so far, in which homopropargyl alcohols were formed predominantly. The structure of allenylzirconium intermediate has been confirmed by X-ray crystal analysis which reveals an intramolecular Zr–N coordination. DFT calculations suggest that the smaller steric effect of the pyridine ring compared with the phenyl
Alkynylation of carbonyl compounds with trimethylsilylacetylenes in the presence of a catalytic amount of Lewis bases such as acetate or phenoxide anion is described. The alkynylation proceeded under mild conditions and afforded the corresponding propargyl alcohols in good to excellent yields.
Electronic Effects in the Pt-Catalyzed Cycloisomerization of Propargylic Esters: Synthesis of 2,3-Disubstituted Indolizines as a Mechanistic Probe
作者:Alison R. Hardin、Richmond Sarpong
DOI:10.1021/ol701973s
日期:2007.10.1
[GRAPHICS]The initial 5-exo versus 6-endo cyclization of the acyl group onto the activated alkyne of propargylic esters has been found to be dependent on electronic effects of the acyl, alkyne, and propargylic carbon substituents. These electronic effects control the ratio of 2,3-disubstituted versus 1,3-disubstituted indolizine products formed when substrates bearing pyridines at the alkyne terminus are used.
Low Temperature Organocopper-Mediated Two-Component Cross Coupling/Cycloisomerization Approach Toward N-Fused Heterocycles
Organocopper reagents smoothly react with heterocyclic propargyl mesylates at low temperature to produce Mused heterocycles. The copper reagent plays a "double duty" in this novel cascade transformation, which proceeds via an S(N)2' substitution followed by a subsequent cycloisomerization step.
Chernyak; Gevorgyan, Chemistry of Heterocyclic Compounds, 2012, vol. 47, # 12, p. 1516 - 1526