Photoinduced molecular transformations. 158. A total synthesis of (.+-.)-methyl piperitol: An unsymmetrically substituted 2,6-diaryl-3,7-dioxabicyclo[3.3.0]octane lignan

Orito, Kazuhiko; Sasaki, Takahiro; Suginome, Hiroshi

doi:10.1021/jo00124a045

Cited by 18 publications

(5 citation statements)

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“…The Bayer-Villiger oxidation of ketones with mCPBA has also been reported for lignans. The 3,7-dioxobicyclo[3,3,0]octane lignan 12 gave the corresponding dilactone product 13 (Scheme 8) [39,40]. In the total synthesis of taiwanin E, the last two steps consist of Baeyer-Villiger of an aldehyde ( 14 ) to the corresponding formate ( 15 ), followed by hydrolysis by MeOH and K 2 CO 3 to the alcohol (Scheme 9) [41].…”

Section: Non-metal-mediated Oxidationsmentioning

confidence: 99%

Oxidative Transformations of Lignans

Runeberg¹,

Brusentsev²,

Rendon³

et al. 2019

Molecules

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Numerous oxidative transformations of lignan structures have been reported in the literature. In this paper we present an overview on the current findings in the field. The focus is put on transformations targeting a specific structure, a specific reaction, or an interconversion of the lignan skeleton. Oxidative transformations related to biosynthesis, antioxidant measurements, and total syntheses are mostly excluded. Non-metal mediated as well as metal mediated oxidations are reported, and mechanisms based on hydrogen abstractions, epoxidations, hydroxylations, and radical reactions are discussed for the transformation and interconversion of lignan structures. Enzymatic oxidations, photooxidation, and electrochemical oxidations are also briefly reported.

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Section: Non-metal-mediated Oxidationsmentioning

confidence: 99%

Oxidative Transformations of Lignans

Runeberg¹,

Brusentsev²,

Rendon³

et al. 2019

Molecules

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“…An unusual strategy towards symmetrical exo,exo-furofurans involved elaboration of the 3,7-dioxobicyclo[3.3.0]octane-2,6-dicarboxylate 119, followed by transformation of the carbocyclic core to the furofuran system (Scheme 42). [85][86][87] Arylation of the 2-and 6-positions (furofuran numbering) of 119 using organolead reagents proceeded in good yield to provide the symmetrically substituted bicyclic system 120. Hydrogenolysis of the benzyl esters, and spontane-ous decarboxylation gave a mixture of products favouring the endo,endo-isomer.…”

Section: Radical and Photochemical Strategiesmentioning

confidence: 99%

“…Acid-promoted equilibration followed by an extremely sluggish and low yielding Baeyer The methodology was subsequently used to prepare unsymmetricaly substituted exo,exo-furofurans, although both the initial arylation reaction and the radical induced b-scission/reductive cyclisation reactions were relatively low yielding. 86 Wirth has described an asymmetric approach towards the construction of the lower tetrahydrofuran ring in the furofurans using organoselenium intermediates in the key steps. 88,89 Thus, diastereoselective alkoxyselenation of protected cinnamyl alcohol derivative 124 with an enantiomerically enriched selenium triflate reagent and allenyl alcohol afforded 125 (d.r.…”

Section: Radical and Photochemical Strategiesmentioning

confidence: 99%

Synthesis of Furofuran Lignans

Brown¹,

Swain²

2004

Synthesis

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This review covers synthetic routes to lignans belonging to the 2,6-disubstituted dioxabicyclo[3.3.0]octane subclass (also known as furofurans). The different approaches have been loosely categorised according to the synthetic strategies applied. The routes discussed range from the classical biomimetic oxidative coupling of cinnamyl derivatives to more recent asymmetric syntheses. 1 Introduction 2 Synthetic Routes to Furofurans 2.1 Oxidative Dimerisation of Cinnamyl Alcohols and Cinnamic Acids and Enolate Anions 2.2 Approaches Based on Conjugate Addition of Acyl Anion Equivalents 2.3 Approaches Based on Aldol Chemistry 2.4 Approaches Based on Cycloaddition/Rearrangement 2.5 Radical and Photochemical Strategies 2.6 Transition Metal Mediated Strategies 3 Concluding Remarks

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“…[1,2] Prior to and following these advances,u seful transition-metal-free a-arylation processes have been developed that involve stoichiometric reactions of enolate anions (or equivalents) with electrophilic aromatic derivatives of Bi V , [3] Pb IV , [4] I(III), [5] S(IV), [6] or benzyne. [1,2] Prior to and following these advances,u seful transition-metal-free a-arylation processes have been developed that involve stoichiometric reactions of enolate anions (or equivalents) with electrophilic aromatic derivatives of Bi V , [3] Pb IV , [4] I(III), [5] S(IV), [6] or benzyne.…”

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confidence: 99%

“…The appendage of an aryl substituent to the a-position of ac arbonyl moiety remains at ransformation of central importance in synthetic organic chemistry.T he advent of powerful metal-catalysed coupling processes has paved the way for the introduction of catalytic (involving mainly organometallic complexes of Pd and Cu) coupling reactions that join aryl halides (or equivalents) to carbonyl-derived enolates. [1,2] Prior to and following these advances,u seful transition-metal-free a-arylation processes have been developed that involve stoichiometric reactions of enolate anions (or equivalents) with electrophilic aromatic derivatives of Bi V , [3] Pb IV , [4] I(III), [5] S(IV), [6] or benzyne. [7] Stepwise methods via initial formation of N-alkoxyenamines [8] or enolonium equivalents followed by nucleophilic attack have also been used for the a-arylation of ketones.…”

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confidence: 99%