Chromium-Mediated Asymmetric Synthesis of Both Enantiomers of Acetoxytubipofuran

Kündig, E. Peter; Cannas, Rita; Laxmisha, M. S.; Liu, Ronggang; Tchertchian, Sylvie

doi:10.1021/ja029957n

Cited by 48 publications

(19 citation statements)

References 16 publications

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“…Kundig 20 achieved success utilizing stoichiometric chiral additives, or chiral directing groups in his asymmetric synthesis of both enantiomers of the natural product acetoxytubipofuran exploiting Cr(CO)3mediated dearomatization (Scheme 15).…”

Section: Elaboration Of Cr- Fe-and Ru-complexes With Planar Chiralitymentioning

confidence: 99%

Asymmetric organic synthesis with stoichiometric transition metal complexes

Malinakova¹

2021

Arkivoc

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Significant recent contributions to the advancement of asymmetric organic synthesis featuring transformations of stoichiometric transition metal complexes are described. Studies that led to the development of powerful synthetic methodologies, as well as projects aimed at elucidation of relevant fundamental concepts, are included. A particular emphasis is placed on applications of complexes with planar chirality.

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Section: Elaboration Of Cr- Fe-and Ru-complexes With Planar Chiralitymentioning

confidence: 99%

Asymmetric organic synthesis with stoichiometric transition metal complexes

Malinakova¹

2021

Arkivoc

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“…The older synthetic strategy involves the Robinson ring annulation sequence, 2 with no provision for substitution at C-1 without lengthy and low yielding oxidations. The newer strategies include cationic cyclization to D, 8 aldol cyclization to E, 9 tricarbonylchromium dearomatization and aldol cyclization to F, 10 and biomimetic ionic cyclization to G.…”

Section: Introductionmentioning

confidence: 99%

A concise synthesis of the 1,6-disubstituted eudesmane sesquiterpene carbon skeleton

Vieira¹,

Nakamura²,

Finelli³

et al. 2007

J. Braz. Chem. Soc.

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“…We here report the total synthesis of 15-acetoxytubipofuran in both racemic and enantiomerically pure form, in which the chromium-mediated dearomatization serves as the key transformation. A preliminary report of part of this work has been published [8].…”

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confidence: 99%

Chromium‐Mediated Dearomatization: Application to the Synthesis of Racemic 15‐Acetoxytubipofuran and Asymmetric Synthesis of Both Enantiomers

Kündig

Laxmisha

Cannas

et al. 2005

Helvetica Chimica Acta

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An efficient dearomatization process of [Cr(arene)(CO) 3 ] complexes initiated by a nucleophilic acetaldehyde equivalent is detailed. It generates in a one-pot reaction three CÀC bonds and two stereogenic centers. This process allowed a rapid assembly of a cis-decalin ring system incorporating a homoannular diene unit in just two steps starting from aromatic precursors (Scheme 2). The method was applied to the total synthesis of the eudesmane-type marine furanosesquiterpene (AE)-15-acetoxytubipofuran (2). Two routes were successfully used to synthesize the g-lactone precursor of the furan ring. The key step in the first approach was a Pd-catalyzed allylic substitution (Scheme 3), while in the second approach, an Eschenmoser ± Claisen rearrangement was highly successful (Scheme 4). The Pd-catalyzed allylic substitution could be directed to give either the (normal) product with overall retention as major diastereoisomer or the unusual product with inversion of configuration (see Table). For the synthesis of the (À)-enantiomer (R,R)-2 of 15-acetoxytubipofuran, an enantioselective dearomatization in the presence of a chiral diether ligand was implemented (Scheme 7), while the ()-enantiomer (S,S)-2 was obtained via a diastereoselective dearomatization of an arene-bound chiral imine auxiliary (Scheme 8). Chiroptical data suggest that a revision of the previously assigned absolute configuration of the natural product is required.Introduction. ± Tricarbonylchromium-mediated dearomatization provides an efficient access to polysubstituted cyclohexadienes [1]. Up to three C-substituents can be added across an arene double bond in a one-pot procedure in a regio-and stereoselective manner by a sequential nucleophilic/electrophilic addition or by a nucleophilic addition followed by an acylation/alkylation sequence [2]. This dearomatization method has seen considerable development, with recent efforts mainly directed towards asymmetric variants of this reaction to give enantiomerically enriched products. Four different asymmetric methods have been developed: asymmetric induction with complexes of arenes bearing a chiral auxiliary as substituent [3], use of arene complexes possessing planar chirality [4], use of prochiral complexes with chiral nucleophiles [5], and use of complexes containing a chiral ligand at the chromium atom [6]. Benchmark enantio-and diastereoselectivities have been obtained in dearomatizations with these methods. In all but the last method, asymmetric induction takes place during the nucleophilic addition step. The third method offers an enantioselective variant in that chirality can be centered on an external ligand rather than on the nucleophile itself, and first results of the use of substoichiometric quantities of chiral information have been realized [7].In all of the dearomatization processes mentioned above, the products possess a homoannular cyclohexadiene moiety. This subunit embedded in a cis-decalin ring

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Chromium-Mediated Asymmetric Synthesis of Both Enantiomers of Acetoxytubipofuran

Cited by 48 publications

References 16 publications

Asymmetric organic synthesis with stoichiometric transition metal complexes

Asymmetric organic synthesis with stoichiometric transition metal complexes

A concise synthesis of the 1,6-disubstituted eudesmane sesquiterpene carbon skeleton

Chromium‐Mediated Dearomatization: Application to the Synthesis of Racemic 15‐Acetoxytubipofuran and Asymmetric Synthesis of Both Enantiomers

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