The reaction of cyano-carbalkoxy-pyridinium-methylids with dimethyl acetylenedicarboxylate

Leonte, C.; Zugrăvescu, I.

doi:10.1016/s0040-4039(01)85032-2

Cited by 12 publications

(1 citation statement)

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“…The chemistry of cycloimmonium ylide has engaged the attention of chemists because of their importance as useful intermediates in the synthesis of novel heterocyclics. Despite the wide applicability of cycloimmonium ylide (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11) in synthetic studies, no information is available concerning the 1,3-dipolar cycloaddition reactions of methyl-substituted pyridinium ylide.…”

Section: Introductionmentioning

confidence: 99%

A synthetic approach toward the synthesis of indolizines via 1,3-dipolar cycloaddition reactions of cycloammonium ylide

Tewari¹,

Bajpai²

1985

J. Chem. Eng. Data

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Dehydrohalogenatlon of N-(2-aroylmethyl)9-plcollnlum and -4-picollnlum bromlde, prepared by the quanternlzation of corresponding bromlde salt with triethylamine, afforded a hlghly reactive cyclolmmonlum yllde. Its 1,3-dipolar cycloaddition reactions with varlous dipolarophlles have been lnvestlgated. These reactions ultlmately result in the formation of novel heterocycllc compounds. The structural assignment of the products were made on the basis of elemental analyses and spectroscopic data. I ntroductlonThe chemistry of cycloimmonium ylide has engaged the attention of chemists because of their importance as useful intermediates in the synthesis of novel heterocyclics. Despite the wide applicability of cycloimmonium ylide ( 7 -7 7 ) in synthetic studies, no information is available concerning the 1,3-dipolar cycloaddition reactions of methyl-substituted pyridinium ylide.I n the course of our investigations on the preparative utility of cycloimmonium ylide, we wish to report the syntheses and physical and spectral properties of indolizines having biological activities. Results and DiscussionTreatment of w-bromo ketones with picolines in anhydrous benzene at reflux temperature lead to the quarternization of picolines giving N-(2-aroylmethyl)picolinium bromides (Scheme I), in excellent yield. The bromide salts when treated with triethylamine in dry benzene immediately generated a dark red coloration due to the formation of corresponding ylide, which on subsequent reaction with various dipolarophiles (acetylenic esters) gave five-membered heterocyclic derivatives (5a-d, 7a-d).( 4 a 4 , 6a-d 1The reaction of picolinium ylides with the acetylenic triple bond of acetylenic ester such as dimethyl acetylenedicarboxylate and diethyl acetylenedicarboxylate appears to proceed by the nucleophilic attack of the carbanion similar to the first step of Michael type of addition. The stabilization of this zwitterion presumably takes place by internal nucleophilic attack of the carbanion on the a-position of the picoline ring

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