Active template rotaxane synthesis through the Ni-catalyzed cross-coupling of alkylzinc reagents with redox-active esters

Echavarren, Javier; Gall, Malcolm A. Y.; Haertsch, Adrian; Leigh, David A.; Marcos, Vanesa; Tetlow, Daniel J.

doi:10.1039/c9sc02457c

Cited by 14 publications

(10 citation statements)

References 62 publications

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“…Active template synthesis [24][25][26][27][28][29][30][31][32][33][34][35] , in which a macrocycle accelerates a strand-forming reaction through the ring cavity, does not require strong pre-association of the starting materials. Although most active template syntheses have been developed from transition metal catalyzed reactions [24][25][26][27][28][29][30][31][32][33][34][35] , a metal-free active template system was recently discovered 36,37 in which the addition of primary amines to electrophiles can be significantly accelerated through crown ethers 37 and related macrocycles 36 by stabilization of the reaction transition state [38][39][40][41][42][43] . The reaction of a primary amine and an electrophile in the presence of a crown ether was found 37 to form [2]rotaxanes by metal-free active template Nalkylation, aza-Michael addition or N-acylation.…”

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Weak functional group interactions revealed through metal-free active template rotaxane synthesis

et al. 2020

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Modest functional group interactions can play important roles in molecular recognition, catalysis and self-assembly. However, weakly associated binding motifs are often difficult to characterize. Here, we report on the metal-free active template synthesis of [2]rotaxanes in one step, up to 95% yield and >100:1 rotaxane:axle selectivity, from primary amines, crown ethers and a range of C=O, C=S, S(=O) 2 and P=O electrophiles. In addition to being a simple and effective route to a broad range of rotaxanes, the strategy enables 1:1 interactions of crown ethers with various functional groups to be characterized in solution and the solid state, several of which are too weakor are disfavored compared to other binding modesto be observed in typical host-guest complexes. The approach may be broadly applicable to the kinetic stabilization and characterization of other weak functional group interactions.

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Weak functional group interactions revealed through metal-free active template rotaxane synthesis

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“…The methodology allowed the preparation of a range of alkyl-coupled products 41 along with several interesting natural products in acceptable yields and high chemoselectivities. 48 through the coupling of a protected long-chain dialkylzinc reagent 43 with a TCNHPI ester 42 of the appropriate carboxylic acid (Scheme 21b). 50 In recent work, the Baran group communicated an innovative approach for the enantioselective transformation of alkyl carboxylic acids to the doubly functionalized alkylated and arylated compounds by exploiting sequential Pd-catalyzed C α −H/C β −H arylation of alkyl carboxylic acids followed by Ni-catalyzed TCNHPI-mediated alkylation.…”

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confidence: 99%

Single Electron Transfer-Induced Redox Processes Involving N-(Acyloxy)phthalimides

et al. 2021

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The past decade has witnessed the emergence of N-(acyloxy)phthalimides (NHPI esters) and its derivatives at the forefront of synthetic methods facilitating the construction of diverse molecular frameworks from the readily available carboxylic acid feedstock. The NHPI esters are predisposed to undergo reductive fragmentation via a single electron transfer (SET) process under thermal, photochemical, or electrochemical conditions to generate the corresponding carbon-or nitrogencentered radicals that participate in a multitude of synthetic transformations to forge carbon−carbon and carbon−heteroatom bonds. The chemistry involving NHPI esters has received broad applicability not only in well-designed cascade annulations but also in medicinal chemistry and natural product synthesis. This comprehensive Review, broadly categorized according to the nature of the bond formation, details the progress made in this field since the initial discovery by providing representative examples with mechanistic details, with an emphasis on challenges and future directions.

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“…Besides the broad applications in the synthesis and/or modification of natural products and complex compounds, the Ni-catalyzed decarboxylation was recently applied in Leigh and co-workers rotaxane assembly, in which unsymmetrical axle [2]rotaxanes were constructed by using the Ni-catalyzed C(sp 3 )-C(sp 3 ) cross-coupling of RAEs (formed directly from carboxylic acids and TCNHPI) and organozinc reagents (derived from alkyl bromides). 25…”

Section: Review Synthesismentioning

confidence: 99%

Recent Progress in Radical Decarboxylative Functionalizations Enabled by Transition-Metal (Ni, Cu, Fe, Co or Cr) Catalysis

2020

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Aliphatic carboxylic acids are abundant in natural and synthetic sources and are widely used as connection points in many chemical transformations. Radical decarboxylative functionalization promoted by transition-metal catalysis has achieved great success, enabling carboxylic acids to be easily transformed into a wide variety of products. Herein, we highlight the recent advances made on transition-metal (Ni, Cu, Fe, Co or Cr) catalyzed C–X (X = C, N, H, O, B, or Si) bond formation as well as syntheses of ketones, amino acids, alcohols, ethers and difluoromethyl derivatives via radical decarboxylation of carboxylic acids or their derivatives, including, among others, redox-active esters (RAEs), anhydrides, and diacyl peroxides.1 Introduction2 Ni-Catalyzed Decarboxylative Functionalizations3 Cu-Catalyzed Decarboxylative Functionalizations4 Fe-Catalyzed Decarboxylative Functionalizations5 Co- and Cr-Catalyzed Decarboxylative Functionalizations6 Conclusions

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Active template rotaxane synthesis through the Ni-catalyzed cross-coupling of alkylzinc reagents with redox-active esters

Abstract: The Ni-catalyzed C(sp3)–C(sp3) cross-coupling of redox-active esters and organozinc reagents is used for the active template synthesis of ‘impossible’ rotaxanes.

Cited by 14 publications

References 62 publications

Weak functional group interactions revealed through metal-free active template rotaxane synthesis

Weak functional group interactions revealed through metal-free active template rotaxane synthesis

Single Electron Transfer-Induced Redox Processes Involving N-(Acyloxy)phthalimides

Recent Progress in Radical Decarboxylative Functionalizations Enabled by Transition-Metal (Ni, Cu, Fe, Co or Cr) Catalysis

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