Synthesis of Diverse Azolo[<i>c</i>]quinazolines by Palladium(II)‐ Catalyzed Aerobic Oxidative Insertion of Isocyanides

Vlaar, TjÃ ̧stil; Bensch, Lisa; Kraakman, Jasper; Velde, Christophe M. L. Vande; Maes, Bert U. W.; Orru, Romano V. A.; Ruijter, Eelco

doi:10.1002/adsc.201301129

“…In as imilar process,2 -(2aminophenyl)tetrazoles 129 and N-(benzimidazol-2-yl)guanidine 132 [62] proved to be suitable substrates (Scheme 32 b, c). Compared to the Pd-catalyzed process, [63] cobalt catalysis has ah igher tolerance for aliphatic and aromatic isocyanides. Unfortunately,O 2 seems not to be asuitable oxidant.…”

Section: Angewandte Chemiementioning

confidence: 99%

Base Metal Catalyzed Isocyanide Insertions

Collet

¹

,

Roose

²

,

Ruijter

³

et al. 2019

Self Cite

View full text Add to dashboard Cite

Isocyanides are diverse C1 building blocks considering their potential to react with nucleophiles, electrophiles, and radicals. Therefore, perhaps not surprisingly, isocyanides are highly valuable as inputs for multicomponent reactions (MCRs) and other one‐pot cascade processes. In the field of organometallic chemistry, isocyanides typically serve as ligands for transition metals. The coordination of isocyanides to metal centers alters the electronic distribution of the isocyano moiety, and reaction pathways can therefore be accessed that are not possible in the absence of the metal. The tunable reactivity of the isocyanide functional group by transition metals has evolved into numerous useful applications. Especially palladium‐catalyzed isocyanide insertion processes have emerged as powerful reactions in the past decade. However, reports on the use of earth‐abundant and cheap base metals in these types of transformations are scarce and have received far less attention. In this Minireview, we focus on these emerging base metal catalyzed reactions and highlight their potential in synthetic organic chemistry. Although mechanistic studies are still scarce, we discuss distinct proposed catalytic cycles and categorize the literature according to 1) the (hetero)atom bound to and 2) the type of bonding with the transition metal in which the (formal) insertion occurs.

show abstract

“…In a similar process, 2‐(2‐aminophenyl)tetrazoles 129 and N ‐(benzimidazol‐2‐yl)guanidine 132 proved to be suitable substrates (Scheme b, c). Compared to the Pd‐catalyzed process, cobalt catalysis has a higher tolerance for aliphatic and aromatic isocyanides. Unfortunately, O 2 seems not to be a suitable oxidant.…”

Section: Insertions Of Isocyanides Into Heteroatom–metal Bondsmentioning

confidence: 99%

Base Metal Catalyzed Isocyanide Insertions

Collet

¹

,

Roose

²

,

Ruijter

³

et al. 2019

Self Cite

View full text Add to dashboard Cite

Isocyanides are diverse C1 building blocks considering their potential to react with nucleophiles, electrophiles, and radicals. Therefore, perhaps not surprisingly, isocyanides are highly valuable as inputs for multicomponent reactions (MCRs) and other one‐pot cascade processes. In the field of organometallic chemistry, isocyanides typically serve as ligands for transition metals. The coordination of isocyanides to metal centers alters the electronic distribution of the isocyano moiety, and reaction pathways can therefore be accessed that are not possible in the absence of the metal. The tunable reactivity of the isocyanide functional group by transition metals has evolved into numerous useful applications. Especially palladium‐catalyzed isocyanide insertion processes have emerged as powerful reactions in the past decade. However, reports on the use of earth‐abundant and cheap base metals in these types of transformations are scarce and have received far less attention. In this Minireview, we focus on these emerging base metal catalyzed reactions and highlight their potential in synthetic organic chemistry. Although mechanistic studies are still scarce, we discuss distinct proposed catalytic cycles and categorize the literature according to 1) the (hetero)atom bound to and 2) the type of bonding with the transition metal in which the (formal) insertion occurs.

show abstract

“…In the cited paper the role of catalyst and mechanism of the reaction was discussed in detail. 17 Li 18 discussed tandem synthesis of 2-(4,5-dihydrothiazol-2-yl)aniline (42) and 2-(4,5-dihydrooxazol-2-yl)aniline (41). It was shown that 2-aminobenzonitrile (34) with 2-mercaptoethylammonia chloride or 2-aminoethanol with various copper catalysts and bases formed compounds 42 and 41, respectively (Scheme 14).…”

Section: Methodsmentioning

confidence: 98%

“…41 It was shown that compounds 62 in reaction with isocyanides in different solvents formed a mixture of two isomeric heterocycles, namely, 2-substituted 5-amino [1,2,4] The structure of key compounds was proven by X-ray diffraction analysis. 41 An effective copper-catalyzed synthesis of N-substituted heterocycles using ligands for the formation of the C-N bond was discussed in the work of Subramanian and Kaliappan 42 (Scheme 38).…”

Section: The Reactivity 2-(azolyl)anilines In Cyclocondensationsmentioning

confidence: 99%

“…41 It was shown that compounds 62 in reaction with isocyanides in different solvents formed a mixture of two isomeric heterocycles, namely, 2-substituted 5-amino [1,2,4] The structure of key compounds was proven by X-ray diffraction analysis. 41 An effective copper-catalyzed synthesis of N-substituted heterocycles using ligands for the formation of the C-N bond was discussed in the work of Subramanian and Kaliappan 42 (Scheme 38). It was shown, that 2-(1H-imidazol-1-yl)-aniline (112a), 2-(1H-benzimidazol-1-yl)aniline (112b), or 2-(1H-1,2,4-triazol-1-yl)aniline (112c) reacted with 2-bromopyridines 113 in DMF in the presence of copper(II) acetate, potassium phosphate, and ligands (phenanthroline monohydrate or tetrabutylammonium iodide) affording 9-phenyl-9H-imidazo[1,2-a]benzimidazole (114a), 5-phenyl-5H-benzimidazo[1,2-a]benzimidazole (114b), or 4-phenyl-4H- [1,2,4]triazolo[1,5-a]benzimidazole (114c), respectively.…”

Section: The Reactivity 2-(azolyl)anilines In Cyclocondensationsmentioning

confidence: 99%

See 1 more Smart Citation