A Facile Two-Step Synthesis of 2-Arylbenzofurans Based on the Selective Cross McMurry Couplings

Duan, Xin-Fang; Zeng, Jing; Zhang, Zhanbin; Zi, Guofu

doi:10.1021/jo7019652

Cited by 84 publications

(50 citation statements)

References 26 publications

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“…It is also relevant here to note that benzofurans so obtained are themselves synthetically and biologically important heterocycles. [5][6][7] We were also curious to see whether isomer maxim-C 6 H 4 ) that suggests the P-aryl to Pd-aryl bond exchange, is described. An interesting structural problem related to the formation/crystallization of benzofurans is also highlighted.…”

Section: Introductionmentioning

confidence: 99%

Pd‐Catalyzed Reactions of Allenylphosphonates and Related Allenes with Functionalized 2‐Iodophenols, 2‐Iodobenzoic Acid, and 2‐Iodobenzyl Alcohol Leading to Functionalized Benzofurans, Isocoumarins, and Benzopyrans

2009

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Regioselective, palladium-catalyzed coupling reactions of allenylphosphonates (OCH 2 CMe 2 CH 2 O)P(O)CH=C=CRRЈ [R, RЈ = H (1a), R = H, RЈ = Me (1b), R = RЈ = Me (1c)] and phenyl allenes PhCH=C=CR 2 [R = H (2a), Me (2b)] with functionalized iodophenols (in PEG-400), 2-iodobenzoic acid, and 2-iodobenzyl alcohol are investigated. Benzofurans with free aldehyde functionalities are formed in high yields ( 1 H/ 31 P NMR) in reactions by using functionalized iodophenols, essentially as single isomers. The synthetic potential of these products possessing an aldehyde functionality is demonstrated by isolating a compound with the skeleton of Obovaten and many other 2,3,5,7-tetrasubstituted benzofurans. From the reaction of 2-iodophenol and Pd II (OAc) 2 /PAr 3 , isolation and structural characterization of the (hydroxy)aryl phosphane oxides (Ar) 2 P(O)(C 6 H 4 -2-OH) (Ar = Ph, 4-MeO-

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Section: Introductionmentioning

confidence: 99%

Pd‐Catalyzed Reactions of Allenylphosphonates and Related Allenes with Functionalized 2‐Iodophenols, 2‐Iodobenzoic Acid, and 2‐Iodobenzyl Alcohol Leading to Functionalized Benzofurans, Isocoumarins, and Benzopyrans

2009

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“…27). 144,145 It is believed that the strong affinity of the heteroatom substituents for the low-valent titanium surface is important for good selectivity. Tandem Cyclizations (Annulations).…”

Section: Scheme 18mentioning

confidence: 99%

The McMurry Coupling and Related Reactions

Takeda

Tsubouchi

2013

Organic Reactions

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The McMurry coupling reaction has been recognized as one of the most efficient methods for the synthesis of alkenes from carbonyl compounds. This reaction can be applied to the preparation of various alkenes that are otherwise difficult to prepare. For example, sterically congested tetrasubstituted alkenes as well as medium to large membered rings involving natural products may be accessed via this process. This coupling utilizes various low‐valent titanium reagents generated by the reduction of titanium (III or IV) chloride with K, Zn, LiAlH 4 , C 8 K, amongst others. Furthermore, a variety of low‐valent metal species other than titanium, including aluminum, zirconium, niobium, molybdenum, indium, tungsten, and samarium, have also been found to promote the reductive coupling of carbonyl compounds. The scope and limitations of these reagent systems are reviewed in this chapter, together with the stereochemistry and reaction mechanism. This reaction is categorized into four coupling modes: i) homocoupling giving symmetrical alkenes, ii) mixed coupling giving unsymmetrical alkenes, iii) intramolecular coupling giving cycloalkenes, and iv) tandem coupling giving cyclic polyenes. Characteristics of these reaction modes are described briefly. A selection of synthetic applications are reviewed, including examples of the preparation of sterically congested and strained alkenes, medium to large‐ring compounds, biologically active targets, as well as substrates applicable in material science. Experimental conditions used for this versatile process are summarized to assist the choice of suitable conditions.

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“…[1][2][3][4][5][6][7][8] The key to this coupling is the formation in situ of Ti(0) from TiCl x using a reducing agent, typically zinc or LiAlH 4 . [9] Because of the expense and hazards associated with TiCl 4 , a route using a catalytic amount of the Ti source would be ideal.…”

Section: Introductionmentioning

confidence: 99%