Cobalt(II)‐Catalyzed Isocyanide Insertion Reaction with Amines under Ultrasonic Conditions: A Divergent Synthesis of Ureas, Thioureas and Azaheterocycles

Zhu, Tong‐Hao; Xu, Xiaoping; Cao, Jianxin; Wei, Tian‐Qi; Wang, Shun‐Yi; Ji, Shun‐Jun

doi:10.1002/adsc.201300745

“…Asimilar Co II -catalyzed transformation using water or elemental sulfur to quench the intermediate alkylcyanamidium 96 leads to unsymmetrical (thio)ureas,again starting from anilines 89. [53] In 2014, Zhu et al devised an ovel approach to the construction of benzo-fused 2-aminoquinolines 98. [54] Under similar catalytic conditions as described in Scheme 23, acomplex of o-aminobiphenyls 97 and Co II X 2 undergoes deprotonation, isocyanide insertion, and one-electron oxidation to afford amidinoyl Co III species 99 (Scheme 25).…”

Section: Insertions Of Isocyanides Into Heteroatom-metal Bondsmentioning

confidence: 99%

Base Metal Catalyzed Isocyanide Insertions

Collet

¹

,

Roose

²

,

Ruijter

³

et al. 2019

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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.

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“…The reaction tolerates primary, secondary, and tertiary isocyanides, but most examples utilize t ‐BuNC ( 14 ). A similar Co II ‐catalyzed transformation using water or elemental sulfur to quench the intermediate alkylcyanamidium 96 leads to unsymmetrical (thio)ureas, again starting from anilines 89 …”

Section: Insertions Of Isocyanides Into Heteroatom–metal Bondsmentioning

confidence: 99%

Base Metal Catalyzed Isocyanide Insertions

Collet

¹

,

Roose

²

,

Ruijter

³

et al. 2019

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

“…Based on literature reports [8b, 10,23] and the chemistry of isocyanides [6], a plausible mechanism is proposed in Scheme 1.…”

Section: Resultsmentioning

confidence: 99%

“…To the best of our knowledge, there are only a few reports of isocyanide insertion-aminobenzothiazole and 2-aminobenzoxazole [8a]. Since Kharaschs pioneering works [9] on the homocoupling reactions of Grignard reagents, cobalt catalysts, which are widely available, not expensive, and have low toxicity, have received particular attention [10].…”

Section: Introductionmentioning

confidence: 99%