A New Method to N-Arylmethylenepyrroles from N-Acylpyrroles

D’Silva, Claudius; Iqbal, R.

doi:10.1055/s-1996-4247

Cited by 20 publications

(13 citation statements)

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“…The N -acylpyrrole 4 was successfully reduced to 4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl) benzyl)- 1H -pyrrole ( 5) using BF 3 /OEt 2 /NaBH 4 . 31 Cleavage of the cyclic boronate ester 5 was attempted using 4M HCl, RT, 18 h, 35 BBr 3 /CH 2 Cl 2 41 and MeOH/TsOH/reflux, but all methods failed to yield the desired product 10 , due to decomposition of the pyrrole group. Milder methods SiO 2 /CH 2 Cl 2 /(COOH) 2 , 42 basic hydrolysis (dioxane/NaOH(aq)) and oxidative cleavage (NaIO 4 /Me 2 CO/aq.…”

Section: Resultsmentioning

confidence: 99%

“…The above reactions, due to the use of basic conditions, the reactivity of pyrrole and activation effects have synthetic limitations, low yields due to the formation of undesirable side products (2-substituted and disubstituted pyrroles) 26–28 and are unsuitable in the preparation of pyrroles containing base labile groups. Recently, we described a procedure to arylmethylene pyrroles based on the reduction of acylpyrroles with (BF 3 .OEt 2 )/NaBH 4 (Scheme 1(b)) 31 and in a further paper 32 a high yield route to N -alkyl pyrroles using the Paal–Knorr method, involving the condensation of primary amines with 2,5-dimethoxytetrahydrofuran (DMT) 20,33,34 using acid-base organic solvent mixtures (Scheme 1(c)).…”

Section: Introductionmentioning

confidence: 99%

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A synthetic route to 1-(4-boronobenzyl)-1H-pyrrole

D’Silva

2021

Journal of Chemical Research

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

A synthetic route to 1-(4-boronobenzyl)-1H-pyrrole

D’Silva

2021

Journal of Chemical Research

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“…Aryl and alkyl N ‐acylpyrroles were synthesized by the acylation of pyrrole with acid chlorides (Scheme , Eqs. (3)and (4)) 11. 12 N ‐Cinnamoylpyrrole ( 4 c ) was prepared by the condensation of cinnamamide with 2,5‐dimethoxytetrahydrofuran in acetic acid [Eq.…”

Section: Methodsmentioning

confidence: 99%

Remarkably Stable Tetrahedral Intermediates: Carbinols from Nucleophilic Additions toN��Acylpyrroles

Evans¹,

Borg²,

Scheidt³

2002

Angew. Chem.

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Tetrahedral intermediates resulting from the addition of nucleophiles to carboxylic acid derivatives are important, short-lived species in acyl-transfer reactions. [1] As a result of their transient nature, the utility of these compounds in organic chemistry remains limited. The isolation of tetrahedral intermediates could provide insight into the acyl-transfer process as well as useful compounds for organic synthesis. While the adducts formed by the addition of organometallic reagents to N-methoxy-N-methylamides [2] and tertiary amides [3] are relatively stable as their corresponding metal alkoxides (2), [4] their protonated counterparts rapidly decompose to the derived carbonyl derivative 3 [Eq.(1)]. [5] Herein, we report a study of the stability and synthetic utility of the exceptionally stable tetrahedral intermediates 5 and 6 resulting from the addition of nucleophiles to N-acylpyrroles 4 [Eq. (2)].

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“…4.5.1.6 Acylation Several useful procedures for N-acylation of pyrroles are available, for example by acyl transfer from 1-acetylimidazole, which offers an efficient route to 1-acetylpyrrole [282]. Alternative attractive methods for N-acylation rely on the use of acetic anhydride [283], or acyl chlorides in the presence of and triethylamine and DMAP as the catalyst [284]. Exposure of pyrroles to di(tert-butyl)dicarbonate in the presence of DMAP in acetonitrile solution gives access to many useful 1-(tert-butoxycarbonyl) pyrroles in high yields [285].…”

Section: Nitrationmentioning

confidence: 99%