Construction of carbazole-based unnatural amino acid scaffolds <i>via</i> Pd(<scp>ii</scp>)-catalyzed C(sp<sup>3</sup>)–H functionalization

Kaur, Ramandeep; Banga, Shefali; Babu, Srinivasarao Arulananda

doi:10.1039/d2ob00658h

Cited by 13 publications

(7 citation statements)

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“…The unique properties of the nitrogen-containing tricyclic 9 H -carbazole prompted its rapid development in various disciplines such as photo-, − electro-, , and medicinal chemistry. ,, The synthesis of the carbazole backbone itself has been extensively documented, and the low cost of the precursor carbazole renders elaborate backbone modification economically viable. ,− …”

Section: Introductionmentioning

confidence: 99%

LNL-Carbazole Pincer Ligand: More than the Sum of Its Parts

Kleinhans,

Karhu,

Boddaert

et al. 2023

Chem. Rev.

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The utility of carbazole in photo-, electro-, and medicinal applications has ensured its widespread use also as the backbone in tridentate pincer ligands. In this review, the aim is to identify and illustrate the key features of the LNL-carbazolide binding to transition metal centers (with L = flanking donor moieties, e.g., C, N, P, and O-groups) in a systematic bottom-up progression to illustrate the marked benefits attainable from (i) the rigid aromatic carbazole scaffold (modulable in both the 1,8-and 3,6-positions), (ii) the significant electronic effect of central carbazole-amido binding to a metal, and the tunable sterics and electronics of both the (iii) flanking donor L-moieties and (iv) the wingtip R-groups on the L-donors, with their corresponding influence on metal coordination geometry, d-electron configuration, and resultant reactivity. Systematic implementation of the ligand design strategies not in isolation, but in a combinatorial approach, is showcased to demonstrate the potential for functional molecules that are not only modulable but also adaptable for wide-ranging applications (e.g., stereoselective (photo)catalysis, challenging small molecule activation, SET and redox applications, and even applications in chemotherapeutics) as an indication of future research efforts anticipated to stem from this versatile pincer assembly, not only for the transition metals but also for s-, p-, and f-block elements.

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Section: Introductionmentioning

confidence: 99%

LNL-Carbazole Pincer Ligand: More than the Sum of Its Parts

Kleinhans,

Karhu,

Boddaert

et al. 2023

Chem. Rev.

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“…Transition metal-catalyzed sp 3 C–H bond functionalization reactions have received paramount attention in recent years. 1–3 Particularly, Pd( ii )-catalyzed, directing group-aided site-selective C–H functionalization has emerged as a valuable method. 2,3 This method has also enabled the diastereoselective functionalization of prochiral C(sp 3 )–H bonds of aliphatic compounds.…”

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confidence: 99%

“…2,3 This method has also enabled the diastereoselective functionalization of prochiral C(sp 3 )–H bonds of aliphatic compounds. 2,3…”

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confidence: 99%

“…We envisioned utilizing the Pd( ii )-catalyzed, directing group (DG)-assisted diastereoselective C–H arylation strategy 2,3 for constructing azobenzene-based unnatural amino acid derivatives. Our strategy involves the initial installation of acetanilide units in amino acids via the Pd( ii )-catalyzed β-C(sp 3 )–H arylation tactic 2,3 by using an iodoacetanilide as the arylating agent. Then, the transformation of the acetanilide unit into an azobenzene motif in the amino acid backbone would afford an azobenzene-based unnatural amino acid scaffold (Scheme 1).…”

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confidence: 99%

“…Towards this, we prepared the DG 8-aminoquinoline (8-AQ) or 2-(methylthio)aniline (MTA) containing racemic and enantiopure N -phthaloyl carboxamides 4 -( dl ), 4 -( l ) and 4 -( d ) from their corresponding α-amino acids. We then subjected amino acid carboxamide 4 -( dl ) to Pd( ii )-catalyzed DG-assisted diastereoselective β-C–H arylation reaction conditions 2,3 using 4-iodoacetanilide ( 5a ) or 3-iodoacetanilide ( 5b ) (Scheme 2). For example, a mixture of leucine derivative 4a -( dl ) containing 8-AQ DG, 4-iodoacetanilide ( 5a , 5 equiv.…”

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confidence: 99%

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Azobenzene-based unnatural amino acid scaffolds via a Pd(ii)-catalyzed C(sp³)–H arylation strategy

et al. 2022

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Pd(II)‐Catalyzed, γ‐C(sp²)−H Alkoxylation in α‐Methylbenzylamine, Phenylglycinol, 3‐Amino‐3‐Phenylpropanol Toward Enantiopure Aryl Alkyl Ethers

et al. 2022

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This paper reports the synthesis of enantiopure aryl alkyl ethers via the Pd(II)-catalyzed picolinamide-aided γ-C(sp 2 )À H alkoxylation of various enantiopure α-alkylbenzylamine derivatives using alcohols. Enantiopure α-methylbenzylamines and amino alcohol substrates such as 2amino-2-phenylethanol (phenylglycinol) and 3-amino-3-phenylpropanol were subjected to the γ-C(sp 2 )À H alkoxylation (etherification) with alcohols using PIDA. α-Alkylbenzylamines and phenylglycinols are valuable building blocks in organic synthesis and medicinal chemistry research areas. Accordingly, this work has enabled the assembling of various enantiopure ortho-alkoxylated α-methylbenzylamine and 2-amino-2-phenylethanol (phenylglycinol) and 3-amino-3-phenylpropanol derivatives containing aryl alkyl ether functionality. We have shown the utility of ortho-alkoxylated αmethylbenzylamine derivatives for assembling enantiopure α-methylbenzylamine-based sulfamoylcarbamates and carboxamides which are structurally related to the bio-active compounds known in the literature. This work demonstrates the substrate scope elaboration in CÀ H functionalization and etherification through the CÀ O bond-forming process and synthesis of aryl alkyl ether functionality containing enantiopure α-alkylbenzylamines.

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Construction of carbazole-based unnatural amino acid scaffolds via Pd(ii)-catalyzed C(sp³)–H functionalization

Abstract: We report the synthesis of carbazole-based unnatural α-amino acid and non-α-amino acid derivatives via the Pd(II)-catalyzed bidentate directing group 8-aminoquinoline-aided β-C(sp3)-H activation/functionalization tactic. Various N-phthaloyl, DL-, L- and D-carboxamides derived...

Cited by 13 publications

References 135 publications

LNL-Carbazole Pincer Ligand: More than the Sum of Its Parts

LNL-Carbazole Pincer Ligand: More than the Sum of Its Parts

Azobenzene-based unnatural amino acid scaffolds via a Pd(ii)-catalyzed C(sp³)–H arylation strategy

Pd(II)‐Catalyzed, γ‐C(sp²)−H Alkoxylation in α‐Methylbenzylamine, Phenylglycinol, 3‐Amino‐3‐Phenylpropanol Toward Enantiopure Aryl Alkyl Ethers

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Construction of carbazole-based unnatural amino acid scaffolds via Pd(ii)-catalyzed C(sp3)–H functionalization

Abstract: We report the synthesis of carbazole-based unnatural α-amino acid and non-α-amino acid derivatives via the Pd(II)-catalyzed bidentate directing group 8-aminoquinoline-aided β-C(sp3)-H activation/functionalization tactic. Various N-phthaloyl, DL-, L- and D-carboxamides derived...

Cited by 13 publications

References 135 publications

LNL-Carbazole Pincer Ligand: More than the Sum of Its Parts

LNL-Carbazole Pincer Ligand: More than the Sum of Its Parts

Azobenzene-based unnatural amino acid scaffolds via a Pd(ii)-catalyzed C(sp3)–H arylation strategy

Pd(II)‐Catalyzed, γ‐C(sp2)−H Alkoxylation in α‐Methylbenzylamine, Phenylglycinol, 3‐Amino‐3‐Phenylpropanol Toward Enantiopure Aryl Alkyl Ethers

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Construction of carbazole-based unnatural amino acid scaffolds via Pd(ii)-catalyzed C(sp³)–H functionalization

Azobenzene-based unnatural amino acid scaffolds via a Pd(ii)-catalyzed C(sp³)–H arylation strategy

Pd(II)‐Catalyzed, γ‐C(sp²)−H Alkoxylation in α‐Methylbenzylamine, Phenylglycinol, 3‐Amino‐3‐Phenylpropanol Toward Enantiopure Aryl Alkyl Ethers