Carboxylates as Nucleophiles in the Enantioselective Ring‐Opening of Formylcyclopropanes under Iminium Ion Catalysis

Díaz, Estibaliz; Reyes, Efraím; Uria, Uxue; Carrillo, Luisa; Tejero, Tomás; Merino, Pedro; Vicario, José L.

doi:10.1002/chem.201801434

Cited by 20 publications

(9 citation statements)

References 100 publications

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“…Vicario and co-workers then reported a desymmetrization of meso-formylcyclopropanes using carboxylic acids as nucleophiles (Scheme 42). 91 Whereas the MacMillan-type imidazolidinones have shown efficient enantioinduction in the two previous examples, proline-derived catalyst 187 containing a bulky silyl group (SiPh 2 Me) improved considerably the enantioselectivity in this case. γ-Acyloxy-substituted aldehydes such as 188−191 were obtained in moderate to high yields and enantioselectivities starting from various carboxylic acids (benzoic or aliphatic) and monocyclic or bicyclic formylcyclopropanes.…”

Section: Ring-opening Reactionsmentioning

confidence: 88%

Catalytic Enantioselective Ring-Opening Reactions of Cyclopropanes

2020

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This review describes the development of enantioselective methods for the ring opening of cyclopropanes. Both approaches based on the reaction of nonchiral cyclopropanes and (dynamic) kinetic resolutions and asymmetric transformations of chiral substrates are presented. The review is organized according to substrate classes, starting by the more mature field of donor−acceptor cyclopropanes. Emerging methods for enantioselective ring opening of acceptor-or donor-only cyclopropanes are then presented. The last part of the review describes the ring opening of more reactive three-membered rings substituted with unsaturations with a particular focus on vinylcyclopropanes, alkylidenecyclopropanes, and vinylidenecyclopropanes. In the last two decades, the field has grown from a proof of concept stage to a broad range of methods for accessing enantioenriched building blocks, and further extensive developments can be expected in the future.

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Section: Ring-opening Reactionsmentioning

confidence: 88%

Catalytic Enantioselective Ring-Opening Reactions of Cyclopropanes

2020

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“… [49] The direct nucleophilic ring‐opening of the activated cyclopropyl iminium ion with carboxylic acid delivered γ‐acyloxy‐substituted aldehyde 93 (Scheme 32 c). [50] …”

Section: Asymmetric Reactions Of Meso‐cyclopropanesmentioning

confidence: 99%

“…[49] Thedirect nucleophilic ring-opening of the activated cyclopropyl iminium ion with carboxylic acid delivered g-acyloxy-substituted aldehyde 93 (Scheme 32 c). [50] Alkylation at the C3-position of indoles with mesodiaminocyclopropanes 94 was achieved by using the modified oxazoline ligand L28/Cu II catalyst (Scheme 33), yielding enantiomerically enriched, diastereomerically pure urea products 95.T his catalytic system could be extended to pyrrole nucleophiles. [51] 7.…”

Section: Asymmetric Reactions Of Meso-cyclopropanesmentioning

confidence: 99%

Asymmetric Catalytic Reactions of Donor–Acceptor Cyclopropanes

2020

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Due to the synergistic “push–pull” effect of vicinal electron‐donating and electron‐withdrawing groups, donor–acceptor (D‐A) cyclopropanes have been recognized as one of the most powerful building blocks to generate polyfunctional reactive intermediates after a strain‐driven ring cleavage. Enantioselective reactions of D‐A cyclopropanes provide an efficient approach to enantioenriched acyclic and cyclic compounds. A number of chiral Lewis/Brønsted acids, transition metals, and organocatalysts have been designed for such transformations, including ring‐openings, annulations, and rearrangements. This minireview highlights the developments and new advances in this field and describes new synthetic opportunities offered by these interesting methodologies.

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“…We have demonstrated computationally the presence of transient carbocations in reactions taking place in one kinetic step including asynchronous concerted cycloadditions [36] and SN 2 -type reactions [37]. Moreover, the real existence of transient carbocations – which are not energy minima – predicted computationally has also been recently proven experimentally in a reaction with an only transition state in which a planar transient species is developed during the reaction [38].…”

Section: Introductionmentioning

confidence: 99%

Transient and intermediate carbocations in ruthenium tetroxide oxidation of saturated rings

Pedrón¹,

Legnani²,

Chiacchio³

et al. 2019

Beilstein J. Org. Chem.

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The ruthenium tetroxide-mediated oxidation of cyclopentane, tetrahydrofuran, tetrahydrothiophene and N-substituted pyrrolidines has been studied computationally by DFT and topological (analysis of the electron localization function, ELF) methods. In agreement with experimental observations and previous DFT calculations, the rate-limiting step of the reaction takes place through a highly asynchronous (3 + 2) concerted cycloaddition through a single transition structure (one kinetic step). The ELF analysis identifies the reaction as a typical one-step-two-stages process and corroborates the existence of a transient carbocation. In the case of pyrrolidines, the carbocation is completely stabilized as an energy minimum in the form of an iminium ion and the reaction takes place in two steps.

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Carboxylates as Nucleophiles in the Enantioselective Ring‐Opening of Formylcyclopropanes under Iminium Ion Catalysis

Cited by 20 publications

References 100 publications

Catalytic Enantioselective Ring-Opening Reactions of Cyclopropanes

Catalytic Enantioselective Ring-Opening Reactions of Cyclopropanes

Asymmetric Catalytic Reactions of Donor–Acceptor Cyclopropanes

Transient and intermediate carbocations in ruthenium tetroxide oxidation of saturated rings

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