Novel and convenient routes to substituted pyrroles and imidazoles
作者:Alan R. Katritzky、Lie Zhu、Hengyuan Lang、Olga Denisko、Zuoquan Wang
DOI:10.1016/0040-4020(95)00851-x
日期:1995.11
pyrroles. Lithiaiion of 6 followed by reactions with imines gives cyclized 4,5-dihydroimidazoles 14 which upon further treatment with ZnBr2 or direct refluxing in toluene yield the 1,25-trisubstituted imidazoles 15 in good yields.
Regioselective Synthesis of Pyrroles from Alkyne-Isocyanide Click Reactions: An Angle Strain-Induced Bond Migration Approach
作者:Jimil George、Hun Young Kim、Kyungsoo Oh
DOI:10.1002/adsc.201601017
日期:2016.12.7
direct regioselective synthesis of highly functionalized pyrroles with two different electron‐withdrawing groups has been developed using an angle strain‐induced 1,2‐shift of an electron‐withdrawing group in 2H‐pyrroles. The preferential migration aptitude of an electron‐withdrawing group over alkyl and aryl groups is believed to be the result of the orbital overlap between the internal alkene and the
N-PROTONATED AZOMETHINE YLIDES WITH A LEAVING GROUP AS SYNTHETIC EQUIVALENTS FOR NONSTABILIZED NITRILE YLIDES
作者:Otohiko Tsuge、Shuji Kanemasa、Koyo Matsuda
DOI:10.1246/cl.1985.1411
日期:1985.9.5
steps, N-(silylmethyl)amidines generate N-protonated azomethine ylides which cycloadd to olefins, acetylenes, and aldehydes giving 1- or 2-pyrrolines, pyrroles, and 2-oxazolines, respectively, after the elimination of N-substituted anilines. With this sequence, the amidines are useful synthetic equivalents of nonstabilized nitrileylides.
dipolarophiles proceeded smoothly to give pyrrole or pyrroline derivatives in good to excellent yields. For example, α-silylimidate 1 was treated with 1.2 equiv of trifluorophenylsilane in the presence of 1 equiv of dimethyl acetylenedicarboxylate to give pyrrole 2 in 97% yield. Furthermore, when starting with a secondary α-silylamide, the one-pot synthesis of N-unsubstituted azomethine ylides could
Generation and cycloaddition of less- or non-stabilized azomethine ylides, or nitrileylideequivalents, via unprecedented 1,4-stannatropy of N-(tributylstannylmethyl)thioamides were achieved. The reactions with dipolarophiles, such as electron-deficient alkenes and alkynes, afforded corresponding pyrrolidine and pyrrole derivatives effectively.