PdCl2-Catalyzed Efficient Transformation of Propargylic Amines to (E)-α-Chloroalkylidene-β-lactams
摘要:
The PdCl2-catalyzed cyclocarbonylation reaction of propargylic amines with CuCl2 and benzoquinone afforded (E)-alpha-chloroalkylidene-beta-lactams in moderate to good yields. The formation of the corresponding Z-isomers or five-membered products was not observed. The reaction of the readily available optically active propargylic amines provides a convenient synthesis of the corresponding (E)-alpha-chloroalkylidene-beta-lactams with high ee values. The structure and the stereochemistry of the products were established by the X-ray single-crystal diffraction study of (E)-6d and (E)-6e, which indicates that the stereoselectivity in this reaction is different from what was observed with propargylic alcohols. A rationale for this reaction was proposed.
PdCl2-Catalyzed Efficient Transformation of Propargylic Amines to (E)-α-Chloroalkylidene-β-lactams
摘要:
The PdCl2-catalyzed cyclocarbonylation reaction of propargylic amines with CuCl2 and benzoquinone afforded (E)-alpha-chloroalkylidene-beta-lactams in moderate to good yields. The formation of the corresponding Z-isomers or five-membered products was not observed. The reaction of the readily available optically active propargylic amines provides a convenient synthesis of the corresponding (E)-alpha-chloroalkylidene-beta-lactams with high ee values. The structure and the stereochemistry of the products were established by the X-ray single-crystal diffraction study of (E)-6d and (E)-6e, which indicates that the stereoselectivity in this reaction is different from what was observed with propargylic alcohols. A rationale for this reaction was proposed.
Regio- and Stereoselective Synthesis of Fluoroalkenes by Directed Au(I) Catalysis
作者:Benjamin C. Gorske、Curren T. Mbofana、Scott J. Miller
DOI:10.1021/ol9016782
日期:2009.10.1
Au-catalyzed hydrofluorination reactions of a range of functionalized alkynes are reported. In the presence of an appropriate directing group, localized with particular spacing from the pendant alkyne, regioselective and predictable conversion of the alkyne to the Z-vinyl fluoride may be achieved, In selected cases, yields and selectivities are excellent. Additional experiments with two directing groups installed have established some initial principles with respect to a hierarchy of directing groups and their capacity for influencing hydrofluorination regioselectivity.