Synthesis of macrocyclic terpenoids by intramolecular cyclization. 12. Total synthesis of methyl ceriferate I, a 14-membered ring sesterterpene from scale insects

Kodama, Masashi; Shiobara, Yoshinori; Sumitomo, Hisako; Fukuzumi, Kazuyoshi; Matsuda, Hiroyuki; Miyamoto, Yasuko

doi:10.1021/jo00242a018

Cited by 16 publications

(7 citation statements)

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“…According to our retrosynthetic analysis, the asymmetric synthesis of the key building block B ( 21 ) commenced with two known chemical entities 8 and 10 (Schemes and ). Compound 8 was prepared by isopropylidene protection of l -ascorbic acid, and allyl bromide 10 was made from 3-benzyloxy-1-propanol in four steps according to a reported procedure . Reaction of 8 with 10 at the presence of Na 2 CO 3 instead of the conventionally used K 2 CO 3 gave 3′- O -allyl product 11 (according to the biosynthetic numbering for hongkonoids), which was unstable during the workup and purification procedures due likely to the exposure of OH-2′ and was thereby immediately protected with chloromethyl ethyl ether (EOMCl) after a quick workup to afford 12 in overall 41% isolated yield.…”

Section: Resultsmentioning

confidence: 99%

Structural Elucidation and Bioinspired Total Syntheses of Ascorbylated Diterpenoid Hongkonoids A–D

Zhao

Wang

et al. 2018

J. Am. Chem. Soc.

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Hongkonoids A-D (1-4), the first example of ascorbylated terpenoids featuring a unique 5,5,5-fused tricyclic spiroketal butyrolactone moiety and diterpenoid-derived long chain, were isolated from Dysoxylum hongkongense. Their structures were unambiguously assigned by a combination of spectroscopic data, chemical degradation, X-ray crystallography, CD analysis, and total synthesis. The total syntheses of compounds 1-4 were effectively accomplished by a convergent strategy with the longest linear sequences of 12-14 steps and overall yields of 5.4-9.6%. Notably, we exploited a bioinspired one-pot method to construct the key intermediate 14 from an easily made compound 12 by involving the cascade reactions of an elaborate Claisen rearrangement, deprotections, and a 5-exo-trig cyclization. The desired major epimer 14a was then transformed to the main building block 21. Assembly of 21 and the long chain vinyl iodide 7 was made by an NHK coupling reaction to furnish the framework of 1-4. Some of the hongkonoids and/or synthetic analogs showed significant to moderate inhibitory activities against NF-κB, 11β-HSD1, and sterol synthesis. The most active NF-κB inhibitor 34 exhibited distinct inhibition on the LPS-induced inflammatory responses in RAW 246.7 and primary BMDM cells.

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Section: Resultsmentioning

confidence: 99%

Structural Elucidation and Bioinspired Total Syntheses of Ascorbylated Diterpenoid Hongkonoids A–D

Zhao

Wang

et al. 2018

J. Am. Chem. Soc.

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“…-e g l term is predominant) that the population of the C, form should decrease with an energy gap increase. Thus, the relative order of the C, populations should be Br > C1 > F > 0CH3, instead of the I relative order observed: Br r C1 >> 0CH3 > F. This inversion I of F and 0CH3 suggests the existence of either a particular I stabilizing effect in the C, form of the F derivative (5) or the presence of a destabilizing effect in the C, form of the 0CH3 derivative (8). In fact, it was shown previously (in the analysis I of CH3 derivative 4) that the benzylic strain is destabil-I izing for the C, form.…”

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confidence: 89%

“…To explain the results obtained for the polar substituted derivatives (5)(6)(7)(8)(9)(10)(11)(12)(13)(14), it is useful to divide them into two subgroups: the first one includes mainly the halogen compounds (5-8) while the second contains the oxy derivatives (8)(9)(10)(11)(12)(13)(14). The 0CH3 substituent (8) is included in both subgroups for reference purposes, as will be explained below.…”

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NMR study of π–σ* stereoelectronic interactions in 3-substituted benzocycloheptene derivatives

Aubin¹,

St‐Jacques²

1990

Can. J. Chem.

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IY. AUBIN and M. ST-JACQUES. Can. J. Chem. 68, 543 (1990). Dynamic NMR methods are used to study 3-substituted benzocycloheptene derivatives, useful models for investigating the conformational effect of the stereoelectronic T-u* orbital interaction. The 11 compounds studied are divided in two subgroups, the first one containing mainly halogenated derivatives (F, C1, Br, and 0CH3) and the second consisting of oxy derivatives (OCH3, 0CH2CH3, 0CH=CH2, OAc, p-OPh-R, where R = H, 0CH3, and NO2). The results for the first series show the presence of two chair conformations (C, and C,) characterized by a decreasing C, population with increasing electronegativity of the substituent. This trend suggests the presence of a dominant T-cr* interaction for Cl and Br stabilizing the C, form. The larger C, population observed for F suggests that a strong attractive interaction with the aromatic peri hydrogen is present in this compound. Finally, in the oxy-substituent series, the populations trend does not correspond to that predicted from the T-o* orbital interaction, but the individual population perturbations appear to be caused primarily by electrostatic interactions involving the nonsymmetrical polar substituents.Key words: low temperature NMR, conformational analysis, seven-membered rings, orbital interactions, benzocycloheptene derivatives.Y. AUBIN et M. ST-JACQUES. Can. J. Chem. 68, 543 (1990). On a utilisC des mCthodes de RMN dynamique pour Ctudier des benzocycloheptenes substituCs en position 3 qui sont de bons modeles pour Cvaluer l'effet conformationnel de l'interaction stCrCoClectronique de l'orbitale T-o*. Les 1 1 composts CtudiCs ont Ct C divisCs en deux sous-groupes : le premier comprend principalement des dCrivCs halogCnCs (F, C1, Br et 0CH3) alors que le second est form6 de dtrivts oxygCnCs (OCH3, 0CH2CH3, 0CH=CH2, OAc et p-OPh-R dans lequel R = H, 0CH3 et NO2). Les rksultats obtenus avec la premiere serie de composCs dCmontrent que deux conformations chaises (C, et C,) sont prCsentes et que la population de la conformation C, diminue avec une augmentation de 1'ClectronCgativitC du substituant. Cette tendance suggere que, pour les substituants C1 et Br, il existe une interaction T-cr* dominante qui stabilise la forme C,. La prisence d'une population plus Clevte de C, avec le F suggkre que, dans ce composC, l'hydrogene aromatique en pkri exerce une forte interaction attractive. Enfin, dans les composCs oxygCnCs, les variations des populations ne correspondent pas celles que l'on pourrait prCvoir en se basant sur l'interaction de l'orbitale T-IT* ; toutefois, les perturbations dans les populations individuelles semblent reflCter principalement des interactions Clectrostatiques impliquant les substituants polaires qui ne sont pas symCtriques. I Mots cle's : RMN i basse temperature, analyse conformationnelle, cycles 2 sept chainons, interactions orbitales, dCrivCs de benzocyclohept~ne.

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“…With this caveat, we envisioned preparation of compound 1 through a convergent coupling of bromide 2 with the anion derived from a protected aryl unit ( 3 , Scheme ). To prepare the desired bromide 2 , we planned to use a Horner−Wadsworth−Emmons (HWE) condensation to install the C10‘−C11‘ double bond stereoselectively from aldehyde 4 and the known phosphonoester 5 . Aldehyde 4 in turn could be traced to the geraniol derivative 6 and ultimately to geranyl acetate ( 7 ).…”

Section: Resultsmentioning

confidence: 99%

“…To prepare the desired bromide 2, we planned to use a Horner-Wadsworth-Emmons (HWE) condensation to install the C10′-C11′ double bond stereoselectively from aldehyde 4 and the known phosphonoester 5. 12 Aldehyde 4 in turn could be traced to the geraniol derivative 6 and ultimately to geranyl acetate (7).…”

Section: Resultsmentioning

confidence: 99%

Synthesis of Arieianal, a Prenylated Benzoic Acid from Piper arieianum

Odejinmi

Wiemer

2005

J. Nat. Prod.

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Arieianal (1) is a complex prenylated benzoic acid that was isolated from Piper arieianum. It has been synthesized through a convergent sequence that joins a functionalized diterpenoid chain to a protected aromatic core. Key steps include use of a copper enolate for selective displacement of an allylic bromide in the presence of an allylic acetate and a stereoselective Horner-Wadsworth-Emmons condensation to afford the desired E olefin of the isoprenoid side chain. After the diterpenoid chain was joined to the aromatic ring, use of sodium metal in hot sBuOH allowed selective cleavage of two benzyl ether protecting groups, and a sequence of oxidations gave the target compound. This synthesis confirms the structure assigned to the natural product and establishes a route that may be used to prepare more active analogues.

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Synthesis of macrocyclic terpenoids by intramolecular cyclization. 12. Total synthesis of methyl ceriferate I, a 14-membered ring sesterterpene from scale insects

Cited by 16 publications

References 0 publications

Structural Elucidation and Bioinspired Total Syntheses of Ascorbylated Diterpenoid Hongkonoids A–D

Structural Elucidation and Bioinspired Total Syntheses of Ascorbylated Diterpenoid Hongkonoids A–D

NMR study of π–σ* stereoelectronic interactions in 3-substituted benzocycloheptene derivatives

Synthesis of Arieianal, a Prenylated Benzoic Acid from Piper arieianum

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