Condensation of a Chiral Tetrahydro-2-furanthione with Diazocarbonyl Compounds

Takano, Seiichi; Tomita, Shun’ichi; Takahashi, M.; Ogasawara, Kunio

doi:10.1055/s-1987-28190

Cited by 35 publications

(13 citation statements)

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“…[25,26] Interestingly, a few reported examples indicated that the formation of Rh-carbenoids with Rh2(OAc)4 facilitates challenging Barton-Kellogg olefinations. [27][28][29][30] Related to the formation of the thiirane intermediate, an analogous Rh2(OAc)4-catalyzed epoxidation was reported by Doyle and co-workers (Figure 1F). [31] Motivated by our interest in catalyst control over higher-order stereogenicity and the addressability of specific states of halted molecular motors, [32,33] we thus considered the feasibility of stereocontrol with the chiral dirhodium tetracarboxylate catalysts designed by the Davies group.…”

Section: Introductionsupporting

confidence: 66%

Katalysatorkontrollierte stereoselektive Barton‐Kellogg‐Olefinierung

Schmidt¹,

Sparr²

2021

Angewandte Chemie

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Overcrowded alkenes are expeditiously prepared by the versatile Barton-Kellogg olefination and have remarkable applications as functional molecules endowed by their unique stereochemical features. The induced stereodynamics thereby enable the controlled motion of molecular switches and motors while the high configurational stability prevents undesired isomeric scrambling that would impact their essential molecular topology. Bistricyclic aromatic enes are prototypical overcrowded alkenes with outstanding stereochemical properties, but their stereocontrolled preparation is challenging and was thus far only feasible in stereospecific reactions and by the use of chiral auxiliaries. Here, we now report that direct catalyst control is achieved by means of a stereoselective Barton-Kellogg olefination with enantio-and diastereocontrol in the preparation of various bistricyclic aromatic enes. Using Rh2(S-PTAD)4 as catalyst, several diazo compounds were selectively coupled with a thioketone to give one of the four anti-folded overcrowded alkene stereoisomers upon reduction. Moreover, complete stereodivergence was reached by catalyst control in combination with distinct thiirane reductions, providing access to all four stereoisomers with an e.r. of up to 99:1. We envision that the catalyst controlled synthesis of overcrowded alkenes and the possibility for stereodivergence in the Barton-Kellogg olefination will provide a direct and effective route for a broad range of topologically unique overcrowded alkenes for functional molecules, catalysis, energy-and electron transfer, or bioactive compounds.

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Section: Introductionsupporting

confidence: 66%

Katalysatorkontrollierte stereoselektive Barton‐Kellogg‐Olefinierung

Schmidt¹,

Sparr²

2021

Angewandte Chemie

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“…[25,26] Interestingly, a few reported examples indicated that the formation of Rh-carbenoids with Rh 2 (OAc) 4 facilitates challenging Barton-Kellogg olefinations. [27][28][29][30] Related to the formation of the thiirane intermediate, an analogous Rh 2 (OAc) 4 -catalyzed epoxidation was reported by Doyle and co-workers (Figure 1 F). [31] Motivated by our interest in catalyst control over higherorder stereogenicity and the addressability of specific states of halted molecular motors, [32,33] we thus considered the feasibility of stereocontrol with the chiral dirhodium tetracarboxylate catalysts designed by the Davies group.…”

Section: Introductionsupporting

confidence: 64%

“…The Barton–Kellogg olefination essentially involves the coupling of diazo compounds with thioketones—typically in an uncatalyzed reaction—followed by the reduction of the resulting thiirane intermediate [25, 26] . Interestingly, a few reported examples indicated that the formation of Rh‐carbenoids with Rh 2 (OAc) 4 facilitates challenging Barton–Kellogg olefinations [27–30] . Related to the formation of the thiirane intermediate, an analogous Rh 2 (OAc) 4 ‐catalyzed epoxidation was reported by Doyle and co‐workers (Figure 1 F).…”

Section: Introductionmentioning

confidence: 92%

Catalyst‐Controlled Stereoselective Barton–Kellogg Olefination

Schmidt

Sparr

2021

Angew Chem Int Ed

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Overcrowded alkenes are expeditiously prepared by the versatile Barton–Kellogg olefination and have remarkable applications as functional molecules owing to their unique stereochemical features. The induced stereodynamics thereby enable the controlled motion of molecular switches and motors, while the high configurational stability prevents undesired isomeric scrambling. Bistricyclic aromatic enes are prototypical overcrowded alkenes with outstanding stereochemical properties, but their stereocontrolled preparation was thus far only feasible in stereospecific reactions and with chiral auxiliaries. Herein we report that direct catalyst control is achieved by a stereoselective Barton–Kellogg olefination with enantio‐ and diastereocontrol for various bistricyclic aromatic enes. Using Rh2(S‐PTAD)4 as catalyst, several diazo compounds were selectively coupled with a thioketone to give one of the four anti‐folded overcrowded alkene stereoisomers upon reduction. Complete stereodivergence was reached by catalyst control in combination with distinct thiirane reductions to provide all four stereoisomers with e.r. values of up to 99:1. We envision that this strategy will enable the synthesis of topologically unique overcrowded alkenes for functional materials, catalysis, energy‐ and electron transfer, and bioactive compounds.

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“…It is well documented in the literature of Barton–Kellogg olefination that thioketones readily react with diazo compounds without promoters or catalysts 55 56 57 . After examination of the conventional conditions, we realized that the stabilized diazoketone 3 needed to be activated by Rh 2 (OAc) 4 to form the metal-carbenoid intermediate 52 54 67 68 69 70 , which was further trapped by relatively unreactive thioester 4 . The postulated episulfide intermediate 22 was reduced by Cu powder in situ to afford tetrasubstituted olefin 2 in 85% overall yield.…”

Section: Resultsmentioning

confidence: 99%

Total synthesis of clostrubin

Yang

2015

Nat Commun

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Clostrubin is a potent antibiotic against methicillin- and vancomycin-resistant bacteria that was isolated from a strictly anaerobic bacterium Clostridium beijerinckii in 2014. This polyphenol possesses a fully substituted arene moiety on its pentacyclic scaffold, which poses a considerable challenge for chemical synthesis. Here we report the first total synthesis of clostrubin in nine steps (the longest linear sequence). A desymmetrization strategy is exploited based on the inherent structural feature of the natural product. Barton–Kellogg olefination forges the two segments together to form a tetrasubstituted alkene. A photo-induced 6π electrocyclization followed by spontaneous aromatization constructs the hexasubstituted B ring at a late stage. In total, 200 mg of clostrubin are delivered through this approach.

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Condensation of a Chiral Tetrahydro-2-furanthione with Diazocarbonyl Compounds

Cited by 35 publications

References 0 publications

Katalysatorkontrollierte stereoselektive Barton‐Kellogg‐Olefinierung

Katalysatorkontrollierte stereoselektive Barton‐Kellogg‐Olefinierung

Catalyst‐Controlled Stereoselective Barton–Kellogg Olefination

Total synthesis of clostrubin

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