Preparation of oxazolines and oxazoles<i>via</i>a PhI(OAc)<sub>2</sub>-promoted cyclization of<i>N</i>-propargylamides
作者:Wei Yi、Qing-Yun Liu、Xing-Xiao Fang、Sheng-Chun Lou、Gong-Qing Liu
DOI:10.1039/c8ob01474d
日期:——
A metal-free cyclization of N-propargylamides for the synthesis of various oxazolines and oxazoles via a 5-exo-dig process is presented. Using (diacetoxyiodo)benzene (PIDA) as a reaction promoter and lithium iodide (LiI) as an iodine source, intramolecular iodooxygenation of N-propargylamides proceeded readily, leading to the corresponding (E)-5-iodomethylene-2-oxazolines in good to excellent isolated
Intramolecular Pd(II)-Catalyzed Cyclization of Propargylamides: Straightforward Synthesis of 5-Oxazolecarbaldehydes
作者:Egle M. Beccalli、Elena Borsini、Gianluigi Broggini、Giovanni Palmisano、Silvia Sottocornola
DOI:10.1021/jo800621n
日期:2008.6.1
Direct synthesis of 2-substituted 5-oxazolecarbaldehydes was performed by intramolecular reaction of propargylamides through treatment with a catalytic amount of Pd(II) salts in the presence of a stoichiometric amount of reoxidant agent. The heterocyclization process was well-tolerated by a wide range of aryl, heteroaryl, and alkyl propargylamides. This protocol constitutes a valuable synthetic pathway to 5-oxazolecarbaldehydes, alternative to the formylation on oxazole rings, often unsatisfactory in term of regioselectivity and yields.
BELENKIJ, L. I.;CHESKIS, M. A.;ZVOLINSKIJ, V. P.;OBUXOV, A. E., XIMIYA GETEROTSIKL. SOED., 1986, N 6, 826-836
作者:BELENKIJ, L. I.、CHESKIS, M. A.、ZVOLINSKIJ, V. P.、OBUXOV, A. E.