Asymmetric Total Synthesis of Hispidanin A

Deng, Heping; Cao, Wei; Liu, Rong; Zhang, Yanhui; Liu, Bo

doi:10.1002/ange.201700958

Cited by 15 publications

(3 citation statements)

References 73 publications

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“…(E)-and (Z)-stereocomplementary second-step Suzuki-Miyaura cross-coupling using α-chloro-β-tosyloxy-α,β-unsaturated esters. [36,37] and γhydroxybutenolides (Schützenmeister's group). [38]…”

Section: Utilization By Other Groupsmentioning

confidence: 99%

“…That is γ‐aminobutanoic acid (GABA) analogues (Merck's group), [11a] juvenile hormones 0 and I (Shinada's group), [32] deuterium‐labelled geranylgeraniols (Shinada's group), [33] functionalized steroids (Mazet and Li), [34] madangamine A (Chida's group), [35] asymmetric total synthesis of hispidanin A and related diterpenoids (Liu and Qin's group), [36,37] and γ‐hydroxybutenolides (Schützenmeister's group) [38] …”

Section: Utilization By Other Groupsmentioning

confidence: 99%

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Stereocomplementary and Parallel Syntheses of Multi‐Substituted (E)‐, (Z)‐Stereodefined α,β‐Unsaturated Esters: Application to Drug Syntheses

Ashida

Tanabe

2020

The Chemical Record

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Section: Utilization By Other Groupsmentioning

confidence: 99%

Section: Utilization By Other Groupsmentioning

confidence: 99%

Stereocomplementary and Parallel Syntheses of Multi‐Substituted (E)‐, (Z)‐Stereodefined α,β‐Unsaturated Esters: Application to Drug Syntheses

Ashida

Tanabe

2020

The Chemical Record

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“…[9] Theg roup of Baran was the first to develop ag eneral coupling reaction using electron-deficient alkenes as the electrophilic component in both intra-and intermolecular variants in the presence of iron catalysts (Scheme 1Ab). [10] Anumber of other methodological procedures (e.g.,Scheme 1Ac), [11] as well as applications of HATpromoted C À Cb ond formation in natural product synthe-sis, [12] have been subsequently reported. Nevertheless,todate the HAT-initiated process has not been applied to reductively couple alkenes to ketones,d espite the carbonyl group being one of the most common unsaturated groups.W hile radical cyclization onto aC = O p-bond is facile,r ate studies have shown that ring closure of radicals onto carbonyl groups is slower than ring opening of the alkoxy radical counterparts, [13] thus rendering carbonyl groups generally unfavorable as radical acceptors.T his unfavorability is reflected by the limited use of radical cyclizations, with ketones as radical acceptors,t oa ccess cycloalkanols,a lthough in isolated examples haloalkanes, [14] av inylbromide, [15] alkynes, [16] and epoxides [17] have been used as proradicals.…”

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confidence: 98%

Radical Cyclization of Alkene‐Tethered Ketones Initiated by Hydrogen‐Atom Transfer

et al. 2017

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An unprecedented C À Cc oupling reaction between alkenes and ketones by hydrogen-atom transfer,u sing Fe-(acac) 3 and PhSiH 3 in EtOH, is described. This mild protocol features high site selectivity and allows the construction of sterically congested structures containing tertiary alcohols and quaternary centers.T he overall process introduces an ovel strategic bond disconnection for ring-closing reactions.

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Catalytic Enantioselective Formal (4+2) Cycloaddition by Aldol–Aldol Annulation of Pyruvate Derivatives with Cyclohexane‐1,3‐Diones to Afford Functionalized Decalins

2018

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The decalin structure is found in bioactive molecules.W eh ave developed catalytic enantioselective formal (4+ +2) cycloaddition reactions via aldol-aldol cascade reactions between pyruvate-derived diketoester derivatives and cyclohexane-1,3-dione derivatives that affordh ighly functionalized decalin derivatives.The reactions were performed using aq uinidine-derived catalyst under mild conditions.D ecalin derivatives bearing up to six chiral carbon centers including tetrasubstituted carbon centers were synthesized with high diastereo-and enantioselectivities.F ive to six stereogenic centers were generated from achiral molecules with the formation of two C À Cb onds in as ingle transformation resulting in the formation of the decalin system. The decalin ring system is found in diterpenes,diterpenoids, steroids,a nd other bioactive natural products and related molecules ( Figure 1). [1] Decalin derivatives often have antiinflammatory,a nti-bacterial, and anti-tumor activities. [1] Therefore,s ynthesis of functionalized decalin derivatives is of interest in drug discovery efforts and in related research. [2][3][4][5] Construction of the decalin ring system has been performed using cycloadditions, [2] cross coupling, [3] polyene cyclizations and related ene-involved annulations, [4] Robinson annulations [2c,d, 5] and related Michael-aldol reactions, [6] in which the reactions start from Michael additions to a,b-unsaturated ketones.H ere we report organocatalytic enantioselective aldol-aldol annulation cascade reactions to afford functionalized decalin derivatives (Scheme 1).In our strategy,C2symmetric starting materials pyruvatederived diketoester derivatives (dihydropyran derivatives) 1 [7] and cyclohexane-1,3-diones 2 are used for the aldol-aldol annulation cascade reactions to construct new cyclohexane rings,r esulting in the formation of decalin derivatives 3 or 4 (Scheme 1). Ther eaction is expected to generate five or six stereogenic centers,d epending on the substituent of 2.W e hypothesized that appropriate catalysts and conditions would accelerate the reactions of 1 with 2 to afford decalin derivatives 3 and 4 with high diastereo-and enantioselectivities. [8] First, we searched for catalysts and conditions for the reaction of 1a and 2a to afford 3a.Selected results are shown in Table 1. Ther eaction in the presence of triethylamine afforded racemic product 3a in ag ood yield (entry 1). For enantioselective versions of the reaction, the use of (DHQD) 2 AQN [9] with tetraethylammonium bromide (TEAB) as additive in toluene-N-methyl-2-pyrrolidone (NMP) resulted in the formation of 3a in ag ood yield as as ingle diastereomer with high enantioselectivity (er 93:7, entry 4). Addition of TEAB improved the enantioselectivity (entry 2v ersus entry 3). Theu se of toluene-NMP as the solvent improved the solubility of 2a and resulted in faster reaction than the same reaction in toluene without affecting the enantioselectivity (entry 4v ersus entry 3). Theu se of three or more equivalents of 2a did not provide bette...

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Asymmetric Total Synthesis of Hispidanin A

Cited by 15 publications

References 73 publications

Stereocomplementary and Parallel Syntheses of Multi‐Substituted (E)‐, (Z)‐Stereodefined α,β‐Unsaturated Esters: Application to Drug Syntheses

Stereocomplementary and Parallel Syntheses of Multi‐Substituted (E)‐, (Z)‐Stereodefined α,β‐Unsaturated Esters: Application to Drug Syntheses

Radical Cyclization of Alkene‐Tethered Ketones Initiated by Hydrogen‐Atom Transfer

Catalytic Enantioselective Formal (4+2) Cycloaddition by Aldol–Aldol Annulation of Pyruvate Derivatives with Cyclohexane‐1,3‐Diones to Afford Functionalized Decalins

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