Highly stereoselective Ru(ii)–Pheox catalyzed asymmetric cyclopropanation of terminal olefins with succinimidyl diazoacetate

Chanthamath, Soda; Phomkeona, Kesiny; Shibatomi, Kazutaka; Iwasa, Seiji

doi:10.1039/c2cc32706f

Cited by 56 publications

(41 citation statements)

References 23 publications

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“…In 2010, we developed a novel chiral complex, Ru(II)‐phenyloxazoline (Ru(II)‐Pheox) complex, which has a unique C 1 ‐symmetric structure (Figure ). Ru(II)‐Pheox can be easily synthesized from a commercially available benzoic acid derivative, an amino alcohol and a Ru source, and effectively promotes enantioselective intermolecular and intramolecular cyclopropanations with electron‐rich olefins, as well as electron‐deficient olefins, under mild reaction conditions.…”

Section: Introductionmentioning

confidence: 99%

Computational chemical analysis of Ru(II)‐Pheox–catalyzed highly enantioselective intramolecular cyclopropanation reactions

Nakagawa

Nakayama²,

Goto

et al. 2018

Chirality

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Computational chemical analysis of Ru(II)‐Pheox–catalyzed highly enantioselective intramolecular cyclopropanation reactions was performed using density functional theory (DFT). In this study, cyclopropane ring–fused γ‐lactones, which are 5.8 kcal/mol more stable than the corresponding minor enantiomer, are obtained as the major product. The results of the calculations suggest that the enantioselectivity of the Ru(II)‐Pheox–catalyzed intramolecular cyclopropanation reaction is affected by the energy differences between the starting structures 5l and 5i. The reaction pathway was found to be a stepwise mechanism that proceeds through the formation of a metallacyclobutane intermediate. This is the first example of a computational chemical analysis of enantioselective control in an intramolecular carbene‐transfer reaction using C1‐symmetric catalysts.

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Section: Introductionmentioning

confidence: 99%

Computational chemical analysis of Ru(II)‐Pheox–catalyzed highly enantioselective intramolecular cyclopropanation reactions

Nakagawa

Nakayama²,

Goto

et al. 2018

Chirality

Self Cite

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“…Furthermore, applying this protocol to alkenes containing ferrocene ( 2 x ) and Estrone ( Estrone ‐ CHO ) moieties demonstrated the synthetic utility of this methodology. To the best of our knowledge, this is the first general and practical catalytic method for accessing cyclopropane carboxaldehydes in a single step from CHOCHN 2 and alkenes …”

Section: Resultsmentioning

confidence: 99%

Difluoroacetaldehyde N‐Triftosylhydrazone (DFHZ‐Tfs) as a Bench‐Stable Crystalline Diazo Surrogate for Diazoacetaldehyde and Difluorodiazoethane

et al. 2020

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Despite the growing importance of volatile functionalized diazoalkanes in organic synthesis, their safe generation and utilization remain a formidable challenge because of their difficult handling along with storage and security issues. In this study, we developed a bench‐stable difluoroacetaldehyde N‐triftosylhydrazone (DFHZ‐Tfs) as an operationally safe diazo surrogate that can release in situ two low‐molecular‐weight diazoalkanes, diazoacetaldehyde (CHOCHN2) or difluorodiazoethane (CF2HCHN2), in a controlled fashion under specific conditions. DFHZ‐Tfs has been successfully employed in the Fe‐catalyzed cyclopropanation and Doyle–Kirmse reactions, thus highlighting the synthetic utility of DFHZ‐Tfs in the efficient construction of molecule frameworks containing CHO or CF2H groups. Moreover, the reaction mechanism for the generation of CHOCHN2 from CF2HCHN2 was elucidated by density functional theory (DFT) calculations.

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“…We envisioned that redox‐active carbenes [M]‐ 13 a (Scheme c), containing an N ‐hydroxyphthalimide (NHPI) ester leaving group, could become equivalent to all the distinct carbenes 6 – 12 , because of the dual capacity of NHPI esters to act as acyl electrophiles and radical precursors. Their vividly expanding C−C, C−N, C−O, and C−B bond‐forming reactions are well beyond the reach of current divergent strategies towards chiral cyclopropanes . Despite their versatility, the orthogonality of NHPI esters to metal carbenes was unknown, and is reasonable concern when considering their facile irreversible fragmentation upon activation with various transition metals and/or visible light …”

Section: Methodsmentioning

confidence: 99%

General Cyclopropane Assembly by Enantioselective Transfer of a Redox‐Active Carbene to Aliphatic Olefins

et al. 2019

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Asymmetric cyclopropane synthesis currently requires bespoke strategies, methods, substrates, and reagents, even when targeting similar compounds. This approach slows down discovery and limits available chemical space. Introduced herein is a practical and versatile diazocompound and its performance in the first unified asymmetric synthesis of functionalized cyclopropanes. The redox‐active leaving group in this reagent enhances the reactivity and selectivity of geminal carbene transfer. This effect allowed the asymmetric cyclopropanation of various olefins, including unfunctionalized aliphatic alkenes, that enables the three‐step total synthesis of (−)‐dictyopterene A. This unified synthetic approach delivers high enantioselectivities that are independent of the stereoelectronic properties of the functional groups transferred. Our results demonstrate that orthogonally differentiated diazocompounds are viable and advantageous equivalents of single‐carbon chirons.

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Highly stereoselective Ru(ii)–Pheox catalyzed asymmetric cyclopropanation of terminal olefins with succinimidyl diazoacetate

Cited by 56 publications

References 23 publications

Computational chemical analysis of Ru(II)‐Pheox–catalyzed highly enantioselective intramolecular cyclopropanation reactions

Computational chemical analysis of Ru(II)‐Pheox–catalyzed highly enantioselective intramolecular cyclopropanation reactions

Difluoroacetaldehyde N‐Triftosylhydrazone (DFHZ‐Tfs) as a Bench‐Stable Crystalline Diazo Surrogate for Diazoacetaldehyde and Difluorodiazoethane

General Cyclopropane Assembly by Enantioselective Transfer of a Redox‐Active Carbene to Aliphatic Olefins

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