Synthetically useful [1,2-a]-fused pyrroles, e.g. 2,3-dihydro-1H-pyrrolizidines substituted in the 1- and 7-positions, have been generated by acyl radical cyclisation onto pyrroles using N-(omega -acyl)-radicals generated front acyl-selenide precursors. The protocol does not require high pressures of CO. Mechanistic studies indicate the key role of azo radical initiators as oxidants of the intermediate pi -radicals. (C) 2001 Elsevier Science Ltd. All rights reserved.
Organic Reactions in Ionic Liquids: A Simple and Highly Regioselective N-Substitution of Pyrrole
作者:Zhen-Chu Chen、Zhang-Gao Le、Yi Hu、Qin-Guo Zheng
DOI:10.1055/s-2004-829182
日期:——
In ionic liquids [Bmim][PF6] or [Bmim][BF4], pyrrole replaced the halogen atom of an alkyl halide to give the corresponding N-substituted pyrrole in excellent yield. Benzenesulfonyl chloride, p-methylbenzenesulfonyl chloride and benzoylchloride reacted similarly with pyrroles to afford the N-substituted pyrroles in quantitative yield. Michael addition reaction of pyrrole with electrophilic olefins
A new and high yielding synthesis of unstable pyrroles via a modified Clauson-Kaas reaction
作者:Brendon S. Gourlay、Peter P. Molesworth、John H. Ryan、Jason A. Smith
DOI:10.1016/j.tetlet.2005.11.104
日期:2006.1
An investigation of the reaction requirements to effect the Clauson-Kaas pyrrolesynthesis led to the formulation of a new procedure that avoids the contact of pyrroles to heat or strongly acidic conditions that cause decomposition of the desired products. The procedure involves mild hydrolysis of 2,5-dimethoxytetrahydrofuran in water to the activated species 2,5-dihydroxytetrahydrofuran that reacts
Short, enantiogenic syntheses of (-)-indolizidine 167B and (+)-monomorine
作者:Charles W. Jefford、Qian Tang、Alexander Zaslona
DOI:10.1021/ja00009a043
日期:1991.4
The enantiogenic syntheses of (−)-indolizidine 167B (1) and (+)-monomorine (2) are described. D-Norvaline and L-alanine are converted into their 1-pyrrole derivatives by reaction with 2,5-dimethoxytetrahydrofuran. Thereafter, Arndt-Eistert homologation of the N-alkanoic acid substituent, followed by rhodium (II) acetate catalyzed decomposition of its α-diazo ketone derivative, provides the relevant
JEFFORD, CHARLES W.;TANG, QIAN;ZASLONA, ALEXANDER, J. AMER. CHEM. SOC., 113,(1991) N, C. 3513-3518
作者:JEFFORD, CHARLES W.、TANG, QIAN、ZASLONA, ALEXANDER
DOI:——
日期:——
Pentoses and Hexoses as Sources of New Melanoidin-like Maillard Polymers
作者:Roland Tressl、Georg T. Wondrak、Leif-A. Garbe、Ralph-Peter Krüger、Dieter Rewicki
DOI:10.1021/jf970973r
日期:1998.5.1
N-Substituted pyrroles (1), 2-furaldehyde (2), and N-substituted 2-formylpyrroles (3), formed in pentose (hexose) Maillard systems, were identified as components of extraordinary polycondensation activity. The polycondensation was studied in model experiments with N-methylpyrrole (1a)/N-methyl-2-formylpyrrole (3a), N-(2-methoxycarbonylethyl)pyrrole (1b)/N-(2-methoxycarbonylethyl)-2-formylpyrrole (3b), N-methyl-2-formylpyrrole (3a), N-methylpyrrole (1a)/2-furaldehyde (2), and N-(2-methoxycarbonylethyl)pyrrole (1b)/2-furaldehyde (2), respectively. MALDI-TOF-MS spectra indicated regular oligomers of up to 15-30 methine-bridged N-methyl(or N-2-methoxycarbonylethyl)-pyrroles. With participation of aldehyde 2, furan rings instead of pyrrole rings were incorporated. The oligomers 5-11 were isolated and identified by MS and NMR techniques. A complementary experiment with N-methyl-2-[C-13]formylpyrrole ([(CHO)-C-13]-3a)/N-methylpyrrole (1a) was performed. The relevance of the new (type II) melanoidin-like oligomers/polymers in Maillard reactions is discussed and, in conclusion, a corresponding structure for native melanoidins is proposed. The oligomers 5, 6, 8, and 9 were tested for antioxidative activity in an iron(III) thiocyanate assay.