Stereoselective Synthesis of Bicyclic Tertiary Alcohols with Quaternary Stereocenters via Intramolecular Crossed Benzoin Reactions Catalyzed by <i>N</i>-Heterocyclic Carbenes

Ema, Tadashi; Oue, Yoshitaka; Akihara, Kumiko; Miyazaki, Yuki; Sakai, Takashi

doi:10.1021/ol9019293

Cited by 80 publications

(16 citation statements)

References 57 publications

(18 reference statements)

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“…The second approach for the construction of the C14–C6 bond used a Stetter reaction catalyzed by the N-heterocyclic carbene (NHC) from precatalyst 17 developed by Rovis. − The NHC from precatalyst 17 can be used for diastereoselective intramolecular reactions, such as the benzoin reaction with aliphatic aldehydes, , and the Stetter reaction where it was employed by Pettus and Bai in their work toward the tetrapetalones . Because of the ease with which the aldehyde mixture containing 14a and 14b could be prepared from crude extracts of E.…”

Section: Resultsmentioning

confidence: 99%

Biomimetic Synthesis of Mitchellenes B–H from the Abundant Biological Precursor 14-Hydroxy-6,12-muuroloadien-15-oic Acid

Klepp¹,

Sadgrove²,

Legendre³

et al. 2019

J. Org. Chem.

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A step-economic biomimetic synthesis of mitchellenes B–H found in Eremophila sturtii has been achieved. Starting from the putative muurolane biological precursor, redox isomerization of the allylic alcohol gave an epimeric mixture of aldehydes, which could be used as a handle for cyclization onto the C6 position, using Bu3SnH-mediated radical cyclization or NHC-catalyzed Stetter reaction. The NHC-mediated approach was superior as the epimeric mixture underwent a dynamic kinetic resolution during the reaction, and reduction of the mixture with NaBH4 selectively formed the mitchellene ring system in 56% yield for the three steps. In the campaign to obtain the acid-starting material, two new natural products, mitchellene H and a muurolane aldehyde, were isolated. Synthetic procedures to access this family of natural products will enable further studies on their biological properties.

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Section: Resultsmentioning

confidence: 99%

Biomimetic Synthesis of Mitchellenes B–H from the Abundant Biological Precursor 14-Hydroxy-6,12-muuroloadien-15-oic Acid

Klepp¹,

Sadgrove²,

Legendre³

et al. 2019

J. Org. Chem.

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“…Even the macrocyclization reaction led to expected products with moderate yields [ 50 ]. Moreover, the reaction possibilities were expanded to stereoselective synthesis using triazolylidene catalysts [ 51 , 52 , 53 , 54 , 55 , 56 ]. It is worth noting that the enantiomeric excesses highly depended on the size of the newly generated ring.…”

Section: Benzoin Condensationmentioning

confidence: 99%

Organocatalytic Name Reactions Enabled by NHCs

et al. 2020

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Giving reactions the names of their discoverers is an extraordinary tradition of organic chemistry. Nowadays, this phenomenon is much rarer, although already named historical reactions are still often developed. This is also true in the case of a broad branch of N‑heterocyclic carbenes catalysis. NHCs allow many unique synthetic paths, including commonly known name reactions. This article aims to gather this extensive knowledge and compare historical reactions with current developed processes. Furthermore, this review is a great opportunity to highlight some of the unique applications of these procedures in the total synthesis of biologically active compounds. Hence, this concise article may also be a source of knowledge for scientists just starting their adventure with N‑heterocyclic carbene chemistry.

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“…In this regard, an intramolecular cross-benzoin strategy allowed Ema and co-workers to achieve the asymmetric desymmetrization of cyclic 1,3-diketones appended with an aliphatic aldehyde residue. 49,50 This work produced enantioenriched bicyclic adducts bearing two adjacent quaternary stereocenters at the ring junctions (Scheme 24).…”

Section: Benzoin Reactionsmentioning

confidence: 99%

Kinetic Resolution, Dynamic Kinetic Resolution and Asymmetric Desymmetrization by N-Heterocyclic Carbene Catalysis

Risi¹,

Bortolini²,

Carmine³

et al. 2019

Synthesis

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N-Heterocyclic carbenes (NHCs) are now well-established organocatalysts for a large number of asymmetric and non-asymmetric transformations. In the last 15 years, there has been significant interest in using NHCs in kinetic resolution (KR), dynamic kinetic resolution (DKR) and asymmetric desymmetrization reactions for the stereoselective synthesis of enantioenriched compounds, with diverse substrates and activation modes being adopted to this end. This short review brings into focus the progress made on NHC-catalyzed KR, DKR, and asymmetric desymmetrization from 2004 until December 2018. The literature discussed in this article is classified on the basis of the type of reaction involving the NHC catalyst.1 Introduction2 Acylation Strategies2.1 O-Acylation2.2 N-Acylation2.3 C-Acylation3 Aldol-Acylation Processes4 Benzoin Reactions5 Stetter Reactions6 Miscellaneous Approaches7 Conclusion

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Stereoselective Synthesis of Bicyclic Tertiary Alcohols with Quaternary Stereocenters via Intramolecular Crossed Benzoin Reactions Catalyzed by N-Heterocyclic Carbenes

Abstract: Bicyclic tertiary alcohols 1 bearing quaternary stereocenters at the two adjacent bridgehead positions were synthesized with high stereoselectivity via the intramolecular crossed benzoin reactions catalyzed by NHC organocatalysts.

Cited by 80 publications

References 57 publications

Biomimetic Synthesis of Mitchellenes B–H from the Abundant Biological Precursor 14-Hydroxy-6,12-muuroloadien-15-oic Acid

Biomimetic Synthesis of Mitchellenes B–H from the Abundant Biological Precursor 14-Hydroxy-6,12-muuroloadien-15-oic Acid

Organocatalytic Name Reactions Enabled by NHCs

Kinetic Resolution, Dynamic Kinetic Resolution and Asymmetric Desymmetrization by N-Heterocyclic Carbene Catalysis

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