Brønsted-Acid-Catalyzed Intramolecular Carbonyl–Olefin Reactions: Interrupted Metathesis vs Carbonyl-Ene Reaction

Malakar, Tanmay; Zimmerman, Paul M.

doi:10.1021/acs.joc.0c03021

Cited by 14 publications

(9 citation statements)

References 53 publications

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“…Because it embodies a double bond functionalization and a carbon–carbon bond formation in a single step, 6 the Prins reaction remains a key transformation in synthesis, providing direct access to products with common motifs in fragrances and bioactive molecules. 7 Nevertheless, the possibility of side reactions (carbonyl-ene, 8 carbonyl-olefin metathesis, 9 and/or olefin polymerization, among others) can complicate the panorama. For these reasons, designing an efficient, catalytic variant of this reaction, surmounting the challenging control of product selectivity, is extremely desirable.…”

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confidence: 99%

The Catalytic Asymmetric Intermolecular Prins Reaction

2021

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Despite their significant potential, catalytic asymmetric reactions of olefins with formaldehyde are rare and metal-free approaches have not been previously disclosed. Here we describe an enantioselective intermolecular Prins reaction of styrenes and paraformaldehyde to form 1,3-dioxanes, using confined imino-imidodiphosphate ( i IDP) Brønsted acid catalysts. Isotope labeling experiments and computations suggest a concerted, highly asynchronous addition of an acid-activated formaldehyde oligomer to the olefin. The enantioenriched 1,3-dioxanes can be transformed into the corresponding optically active 1,3-diols, which are valuable synthetic building blocks.

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confidence: 99%

The Catalytic Asymmetric Intermolecular Prins Reaction

2021

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“…Moreover, the adsorption site location of ASE is implemented only for certain surfaces, while more advanced surfaces would require manual definitions [179]. Owing to the general, atomistic nature of their core algorithm, the AFIR and GSM method, both Maeda et al [186][187][188] and Zimmerman et al [189][190][191][192][193][194][195][196][197][198][199] have studied homogeneous catalysis more extensively, also incorporating experimental information. Their algorithms can also be applied in a semiautomatic fashion by steering the exploration into certain branches of the reaction network, either by specifying specific internal coordination transformations or fragments of the molecules that shall be combined or dissociated.…”

Section: Computational Catalysis and Mechanism Explorationmentioning

confidence: 99%

Autonomous Reaction Network Exploration in Homogeneous and Heterogeneous Catalysis

Steiner

Reiher

2022

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Autonomous computations that rely on automated reaction network elucidation algorithms may pave the way to make computational catalysis on a par with experimental research in the field. Several advantages of this approach are key to catalysis: (i) automation allows one to consider orders of magnitude more structures in a systematic and open-ended fashion than what would be accessible by manual inspection. Eventually, full resolution in terms of structural varieties and conformations as well as with respect to the type and number of potentially important elementary reaction steps (including decomposition reactions that determine turnover numbers) may be achieved. (ii) Fast electronic structure methods with uncertainty quantification warrant high efficiency and reliability in order to not only deliver results quickly, but also to allow for predictive work. (iii) A high degree of autonomy reduces the amount of manual human work, processing errors, and human bias. Although being inherently unbiased, it is still steerable with respect to specific regions of an emerging network and with respect to the addition of new reactant species. This allows for a high fidelity of the formalization of some catalytic process and for surprising in silico discoveries. In this work, we first review the state of the art in computational catalysis to embed autonomous explorations into the general field from which it draws its ingredients. We then elaborate on the specific conceptual issues that arise in the context of autonomous computational procedures, some of which we discuss at an example catalytic system. Graphical Abstract

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“…It should be noted here again that previous attempts using triflic acid to catalyze COM reactions offen led to different outcomes. 23,24 It was curious that reduced reaction efficiencies were observed for more concentrated or diluted reaction mixture (entries 14-16). Nevertheless, the optimal conditions developed here are milder and more practical than previous reports on other Brønsted acid catalyzed COM systems, which used more complicated reaction setups, elevated temperatures and longer reaction times.…”

Section: Reaction Optimization and Mechanistic Investigationsmentioning

confidence: 99%

“…As discussed earlier, the directed Brønsted acid catalyzed COM reaction in homogeneous conditions is often problematic in that several side processes such as carbonyl-ene, Prins or interrupted carbonylolefin metathesis reactions. 23,24 As our pTSA/HFIP catalytic system marked the first time COM reactions can be carried out in this manner without much of those issues, we would like to expand the work to investigate the scope of its catalytic activity on analogous cyclization reactions. We decided to select a series of aromatic ketones with an unsaturated side chain (1, 3, 5, 7, 9 Scheme 3) and subjected them to the pTSA/HFIP catalytic conditions.…”

Section: Substrate Scope and Further Applicationsmentioning

confidence: 99%

“…Furthermore, the COM reaction is even more suitable for the investigation of our catalysis concept (Scheme 1B2), considering the fact that previous attempts to use superacidic catalysts such as triflic acid to catalyze COM reaction offen led to unsatisfactory or different outcomes. 23,24 Therefore, the use of a hydrogen bond solvent network for catalyst activation and the demonstration of its application in the COM reaction would provide insights into the realization of new biomimetic concepts in catalysis in general and the unprecedented homogeneous Brønsted acid-catalyzed COM reactions in particular (Scheme 1B2).…”

Section: Introductionmentioning

confidence: 99%

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Biomimetic Brønsted Acid-Catalyzed Carbonyl-Olefin Metathesis Enabled by Hydrogen Bonding Networks

Pei

Koenigs

et al. 2021

Preprint

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Synthetic chemists have learned to mimic nature in using hydrogen bonds and other weak interactions to dictate the spatial arrangement of reaction substrates and to stabilize transition states to enable highly efficient and selective reactions. The activation of a catalyst molecule itself by hydrogen bonding networks, in order to control its catalytic activity to achieve desired reaction outcomes is much less explored in organic synthesis, despite being a common strategy in nature. Herein, we show our investigation into this underexplored area by studying the promotion of carbonyl-olefin metathesis reactions by hydrogen bonding-assisted Brønsted acid catalysis. The carbonyl-olefin metathesis reaction has recently emerged as a powerful synthetic tool for functional group interconversion of carbonyls and alkenes. However, the application of Brønsted acid catalysts in carbonyl-olefin metathesis reaction, especially in homogeneous conditions, remains scarce and poorly understood. In this work, we report the use of hexafluoroisopropanol solvent in combination with para-toluenesulfonic acid to efficiently catalyze carbonyl-olefin metathesis reactions. Our experimental and computational mechanistic studies reveal not only an interesting role of HFIP solvent in assisting this Brønsted acid catalyzed reaction but also insightful knowledge about the current limitations of the carbonyl-olefin metathesis reaction.

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Brønsted-Acid-Catalyzed Intramolecular Carbonyl–Olefin Reactions: Interrupted Metathesis vs Carbonyl-Ene Reaction

Cited by 14 publications

References 53 publications

The Catalytic Asymmetric Intermolecular Prins Reaction

The Catalytic Asymmetric Intermolecular Prins Reaction

Autonomous Reaction Network Exploration in Homogeneous and Heterogeneous Catalysis

Biomimetic Brønsted Acid-Catalyzed Carbonyl-Olefin Metathesis Enabled by Hydrogen Bonding Networks

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