PdCl2-catalyzed efficient transformation of propargylic amines to (E)-alpha-chloroalkylidene-beta-lactams.
[reaction: see text] 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.
Ma
Shengming
S
State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin Lu, Shanghai 200032, PR China. masm@mail.sioc.ac.cn
Wu
Bin
B
Jiang
Xuefeng
X