Fundamental Reactions to Cleave Carbon–Carbon σ‐Bonds with Transition Metal Complexes

Murakami, Masahiro; Ishida, Naoki

doi:10.1002/9783527680092.ch1

Cited by 17 publications

(16 citation statements)

References 171 publications

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“…Transition metal (TM) catalyzed carbon–carbon bond (C–C) activation has emerged as a rapidly growing field. 1 In particular, it allows for new strategic bond disconnection, often leading to more complex structures. However, beyond intriguing trans-formations, synthetic utility of these new C–C activation methods remains underdeveloped.…”

Section: Introductionmentioning

confidence: 99%

“…2h As an ongoing research interest, our laboratory has been engaged in developing a so-called “cut- and-sew” strategy for constructing bridged and fused rings through intramolecular insertion of an unsaturated unit into the α C–C bond of a cyclic ketone (Figure 1). 1q,3 In this article, we hope to describe a complete story on the concise total synthesis of indole alkaloid (–)-cycloclavine and its unnatural analogue enabled by a highly enantioselective cut- and-sew transformation 4–6 with nitrogen-tethered benzocyclobutenones and olefins.…”

Section: Introductionmentioning

confidence: 99%

“…Transition metal (TM) catalyzed carbon–carbon bond (C–C) activation has emerged as a rapidly growing field . In particular, it allows for new strategic bond disconnection, often leading to more complex structures.…”

Section: Introductionmentioning

confidence: 99%

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Concise Synthesis of (−)-Cycloclavine and (−)-5-epi-Cycloclavine via Asymmetric C–C Activation

2018

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To illustrate the synthetic significance of C-C activation methods, here we describe an efficient strategy for the enantioselective total syntheses of (-)-cycloclavine and (-)-5- epi-cycloclavine, which is enabled by an asymmetric Rh-catalyzed "cut-and-sew" transformation between benzocyclobutenones and olefins. Despite the compact structure of cycloclavine with five-fused rings, the total synthesis was accomplished in 10 steps with a 30% overall yield. Key features of the synthesis include (1) a Pd-catalyzed tandem C-N bond coupling/allylic alkylation sequence to construct the nitrogen-tethered benzocyclobutenone, (2) a highly enantioselective Rh-catalyzed carboacylation of alkenes to forge the indoline-fused tricyclic structure, and (3) a diastereoselective cyclopropanation for preparing the tetrasubstituted cyclopropane ring. Notably, an improved catalytic condition has been developed for the nitrogen-tethered cut-and-sew transformation, which uses a low catalyst loading and allows for a broad substrate scope with high enantioselectivity (94-99% e.e.). The C-C activation-based strategy employed here is anticipated to have further implications for syntheses of other natural products that contain complex fused or bridged rings.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Concise Synthesis of (−)-Cycloclavine and (−)-5-epi-Cycloclavine via Asymmetric C–C Activation

2018

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“…The recent advancement allows asymmetric C–H functionalization to emerge as a powerful tool for synthesis; by contrast, the corresponding asymmetric C–C cleavage/functionalization, though attractive for preparing chiral complex ring systems, has been much less developed . To date, the scope of transition metal-catalyzed asymmetric C–C activation has been primarily restricted to either the cleavage of an achiral C–C bond, e.g., an aryl–CN bond , or the C1–C8 bond in benzocyclobutenones, , or use of symmetrical substrates − (Scheme a,b). Despite the fact that chiral unsymmetrical C–C bonds are common, the corresponding catalytic asymmetric transformation involving activation of these bonds remains elusive (Scheme c).…”

mentioning

confidence: 99%

Kinetic Resolution via Rh-Catalyzed C–C Activation of Cyclobutanones at Room Temperature

Deng

Lee

et al. 2019

J. Am. Chem. Soc.

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Herein we describe the development of a highly selective kinetic resolution of cyclobutanones via a Rh-catalyzed "cut-and-sew" reaction with selectivity factor up to 785. This reaction takes place at room temperature with excellent efficiency. Various trans-5,6-fused bicycles and C2-substituted cyclobutanones were obtained with excellent ee's that can be further used as chiral building blocks. DFT calculations reveal the crucial roles of the DTBM-segphos ligand in stabilizing the rate-and enantioselectivity-determining C−C oxidative addition transition state via favorable ligand−substrate dispersion interactions.

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“…On the other hand, the transition-metal-catalyzed carbon–carbon bond (C–C) activation of small rings , followed by 2π insertion, namely a “cut-and-sew” process, has found wide utility in constructing various ring systems, , which is generally complementary to conventional cycloaddition reactions. First reported by Murakami and Cramer, the asymmetric intramolecular Type-II cyclobutanone/2π couplings can form [2.2.2] or [3.2.1] bicycles, respectively, based on a distinct benzo-fused scaffold (Scheme b).…”

Section: Introductionmentioning

confidence: 99%

Enantioselective Type II Cycloaddition of Alkynes via C–C Activation of Cyclobutanones: Rapid and Asymmetric Construction of [3.3.1] Bridged Bicycles

Hou

Zhang

et al. 2020

J. Am. Chem. Soc.

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Synthesis of bridged scaffolds via Type II cyclization constitutes substantial challenges due to the intrinsic ring strain accumulated in reaction transition states. Catalytic enantioselective Type II-cyclization methods are even rarer. Here, we describe a detailed study of developing a Rh(I)-catalyzed enantioselective intramolecular Type II cyclization of alkynes via C–C activation of cyclobutanones. This method offers a rapid approach to access a wide range of functionalized [3.3.1]-bridged bicycles along with an exocyclic olefin and an all-carbon quaternary stereocenter. Excellent enantioselectivity has been achieved using a combination of cationic rhodium(I) and DTBM-segphos. Attributed to the redox neutral and strong acid/base-free reaction conditions, high chemoselectivity has also been observed. For the oxygen-tethered substrates, the reaction can proceed at room temperature. In addition, partial kinetic resolution has been achieved for substrates with existing stereocenters, forging interesting chiral tricyclic scaffolds. The methylalkyne-derived substrates gave unexpected dimeric structures in good yield with excellent enantioselectivity and complete diastereoselectivity. Furthermore, the bridged bicyclic products can be diversely functionalized through simple transformations. Finally, mechanistic studies reveal a surprising reaction pathway that involves forming a metal-stabilized anti-Bredt olefin intermediate.

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Fundamental Reactions to Cleave Carbon–Carbon σ‐Bonds with Transition Metal Complexes

Cited by 17 publications

References 171 publications

Concise Synthesis of (−)-Cycloclavine and (−)-5-epi-Cycloclavine via Asymmetric C–C Activation

Concise Synthesis of (−)-Cycloclavine and (−)-5-epi-Cycloclavine via Asymmetric C–C Activation

Kinetic Resolution via Rh-Catalyzed C–C Activation of Cyclobutanones at Room Temperature

Enantioselective Type II Cycloaddition of Alkynes via C–C Activation of Cyclobutanones: Rapid and Asymmetric Construction of [3.3.1] Bridged Bicycles

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