Synthesis of 2-Aminoindolizines by 1,3-Dipolar Cycloaddition of Pyridinium Ylides with Electron-Deficient Ynamides
作者:Julien Brioche、Christophe Meyer、Janine Cossy
DOI:10.1021/acs.orglett.5b01205
日期:2015.6.5
possessing an ynoate or an ynone moiety, have been successfully involved for the first time in a 1,3-dipolarcycloaddition with stabilized pyridiniumylides. These reactions afford an efficient and general access toward a variety of substituted 2-aminoindolizines which can serve as useful precursors for the synthesis of other more complex nitrogen heterocycles.
cycloaddition of pyridinium ylides with alkynes was investigated under mild conditions. A series of 13 pyridinium salts was prepared by alkylation of 4-substituted pyridines. Their reactivity with propiolic ester or amide in various reaction conditions (different temperatures, solvents, added bases) was studied, and 11 indolizines, with three points of structural variation, were, thus, isolated and
Preparation of 1-trifluoroacetyl indolizines and their derivatives via the cycloaddition of pyridinium N-ylides with 4-4-ethoxy1-1,1,1-trifluorobut-3-en-one
Under basic reaction conditions pyridinium or isoquinolinium N-ylides (C5H5N+ CH2YBr− or C9H7N+CH2YBr−, Y : CO2R, CN, PhCO) reacted readily with 4-ethoxyl-1,1,1-trifluorobut-3-en-2-one to give the corresponding 1-trifluoroacetyl substituted indolizines or pyrrolo-[1,2-a]isoquinolines. The molecular structure of 1-trifluoromethyl-3-methoxyl-pyrrolo-[1,2-a]isoquinoline is presented.
Pd-Catalyzed C-3 functionalization of indolizines via C–H bond cleavage
作者:Baoli Zhao
DOI:10.1039/c2ob25643f
日期:——
New transition metal-catalyzed methods for the arylation of indolizines by the direct cleavage of CâH bonds have been developed. A wide range of aryltrifluoroborate salts react with indolizines in the presence of Pd(OAc)2 catalyst and AgOAc oxidant to give the arylated indolizines in high yields. Both electron-donating and electron-withdrawing groups perform smoothly while bromide and chlorine substituents are tolerated. In addition, the indolizines display similar reactivities in the Pd-catalyzed reaction with 3-phenylpropiolic acid to afford the corresponding C-3 alkynylated indolizines. These methods allow the direct functionalization of indolizines in one step.
Stereochemical Study on 1,3-Dipolar Cycloaddition Reactions of Heteroaromatic<i>N</i>-Ylides with Symmetrically Substituted cis and trans Olefins
作者:Otohiko Tsuge、Shuji Kanemasa、Shigeori Takenaka
DOI:10.1246/bcsj.58.3137
日期:1985.11
Stereochemistry of the cycloadditions of twenty-four heteroaromatic N-ylides with several symmetrically substituted cis and trans olefins has been investigated. Cyclic and acyclic cis olefins cycloadd to the and form of the ylides in a highly endo-selective manner giving almost quantitative yields of stereospecific endo 3+2 cycloadducts. N-Ylides stabilized with a substituent of carbonyl type react