The fascinating construction of pyridine ring systems by transition metal-catalysed [2 + 2 + 2] cycloaddition reactions

Heller, Bárbara; Hapke, Marko

doi:10.1039/b607877j

Cited by 500 publications

(95 citation statements)

References 41 publications

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“…Transition metal-catalyzed [2+ 2+2] cycloaddition of unsaturated compounds, such as alkynes, nitriles, alkenes, imines and isocyanates, is the most atom-economical protocol for the synthesis of six-membered ring compounds [61][62][63][64][65][66][67][68][69][70][71][72][73][74]. Although various types of catalysts and substrates have been subjected to the inter-and intramolecular reactions, the development of iron-catalyzed [2+2+2] cycloadditions was very slow and the substrates were mainly focused on the alkynes and nitriles.…”

Section: Construction Of Six-membered Ringsmentioning

confidence: 99%

Recent advances in the iron-catalyzed cycloaddition reactions

Wang

Wan

2012

Chin. Sci. Bull.

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The rapid generation of molecular in a relatively easy manner has made the cycloaddition reaction a powerful tool in the synthesis of different membered ring compounds. Clearly, iron catalysts are becoming a much more interesting and viable choice for this purpose. In this review, a number of promising results in the iron catalyzed cycloaddition reactions in the last decades were summarized. Special attention has been paid to the asymmetric cycloaddition reactions. cycloaddition, iron catalyst, asymmetric Citation:Wang C X, Wan B S. Recent advances in the iron-catalyzed cycloaddition reactions. Chin Sci Bull, 2012, 57: 23382351, doi: 10.1007/s11434-012-5141-z Cycloaddition reaction, which can construct several bonds simultaneously in a single step, is one of the most powerful strategies for the synthesis of cyclic compounds from various unsaturated substrates such as alkynes, alkenes, allenes, nitriles, aldehydes, ketones, imines, etc. Three-, four-, five-, six-or seven-membered rings are obtained through these transformations. The high atom-efficiency, as well as the good tolerance of different functional groups, continues to draw many chemists' attention to this field. In particular, great efforts have been devoted to the development of novel and efficient catalytic systems. However, harsh reaction conditions are often required including heat, light, high pressure or sonication, and the lack of chemo-and/or regioselectivity is also an important problem. Over the past decades, the use of transition metal catalysts has contributed significantly to the development of the cycloaddition reactions and good selectivities were obtained [1]. Among all the available transition metals, iron is generally regarded as one of the most inexpensive, abundant, benign and relatively non-toxic metals [2]. Many transformations have been effectively promoted by iron catalysts, and excellent reviews on the iron-catalyzed reactions are available [3][4][5][6][7][8][9][10][11][12][13][14][15]. Bolm and co-workers [3] summarized the most important transformations with the aid of iron catalysts in 2004, including addition, substitution, cycloaddition, reduction and other reactions. At a later time, they also reviewed the oxidative C-C coupling reactions [4] and the development of carbon-heteroatom and heteroatom-heteroatom bond formation under iron catalysts [5]. The uses of FeCl 3 as catalyst in organic synthesis were covered by Padrón [6] and Bolm [4], and the cross coupling reactions were discussed in detail by Fürstner [7,8]. Recently, direct C-H transformation via iron catalysis was summarized by Shi and co-workers [9]. Applications of iron catalysts on other reactions were also summarized by Bauer [10] However, despite the aforementioned contributions, reviews mainly focus on the iron-catalyzed cycloaddition reactions are rather rare [15]. In this review, we will point out recent advances in this field, most contributions going from 2004 to Nov. 2011. Although every effort has been made to avoid repetition, some overlap with the ...

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Section: Construction Of Six-membered Ringsmentioning

confidence: 99%

Recent advances in the iron-catalyzed cycloaddition reactions

Wang

Wan

2012

Chin. Sci. Bull.

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“…[52] Many synthetic methods have been exploited [53] and the C1-Z cyclization model will be discussed in this section.…”

Section: Pyridine and Pyrimidinementioning

confidence: 99%

The Synthesis of Aromatic Heterocycles from Propargylic Compounds

Jia-Jie¹,

Zhu²,

Zhan³

2012

Asian J Org Chem

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It is well known that the aromatic heterocyclic compounds are the most ubiquitous motifs and are found in many natural products and pharmaceuticals that exhibit remarkable biological activities. Significant effort continues to be given to the development of new methods for their construction. Although a number of methods have been established to construct these compounds, the development of novel methods that allow the facile assembly of substituted heterocycles from readily available starting materials remains an important objective. In recent years, propargylic compounds that contain many reactive centers have attracted a lot of attention for their various transformations. Chemists have conducted a detailed investigation of their cyclization with nucleophiles. The cyclization of propargylic compounds with a variety of nucleophiles is a very efficient method for producing furans, pyrroles, thiazoles, indoles, imidazoles, indolizines, oxazoles, pyridines, quinolines, thiophenes, and so on. In this review, we highlight the substantial progress that has been made in this area between 2000 and mid-2012, and give examples of the reactions of propargylic compounds with a variety of substrates to produce heterocycles.

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“…Over many years, fundamental organic synthesis has revealed a diversity of reactions of alkynes, which provide new C-C, C-N, and C-O bond formation, e.g. in important biomolecules as pyrroles, 6,7 pyridines, 2,[8][9][10] vitamins A and E, 1,11 β-carotene, 11 linalool, 11 citral, 12 steroids, 13,14 etc. In this area of organic synthesis, the application of superbasic media such as alkaline metal hydroxide or alkoxide/DMSO 15 to promote the reactions of alkynes with nucleophiles is a comparatively underestimated approach.…”

Section: Introductionmentioning

confidence: 99%