- Studies directed toward the synthesis of hedycoropyrans: total synthesis of des-hydroxy (?)-hedycoropyran B (ent-rhoiptelol B)
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A full account of our efforts directed towards the synthesis of the diarylheptanoid-derived natural products hedycoropyrans that led to the total synthesis of ent-rhoiptelol B is described. In this endeavor, we have attempted two distinct synthetic strategies to access hedycoropyrans A and B, which led us to establish a facile synthetic route for des-hydroxy (?)-hedycoropyran B (ent-rhoiptelol B) from simple and readily accessible building blocks of 4-allylanisole and vanillin, employing Sharpless asymmetric epoxidation, CBS reduction, and an intramolecular AgOTf-catalyzed oxa-Michael reaction of suitably functionalized hydroxy-ynone as key transformations. The investigations disclosed herein will provide insights into designing novel synthetic routes for THP-DAH-derived natural products.
- Kataria, Priyanka,Nomula, Rajesh,Kontham, Ravindar
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p. 444 - 463
(2022/01/20)
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- Laccase-catalyzed oxidation of allylbenzene derivatives: Towards a green equivalent of ozonolysis
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Laccase-based biocatalytic reactions have been tested with and without mediators and optimized in the oxidation of allylbenzene derivatives, such as methyl eugenol taken as a model substrate. The reaction primarily consisted in the hydroxylation of the propenyl side chain, either upon isomerization of the double bond or not. Two pathways were then observed; oxidation of both allylic alcohol intermediates could either lead to the corresponding α,β-unsaturated carbonyl com-pound, or the corresponding benzaldehyde derivative by oxidative cleavage. Such a process consti-tutes a green equivalent of ozonolysis or other dangerous or waste-generating oxidation reactions. The conversion rate was sensitive to the substitution patterns of the benzenic ring and subsequent electronic effects.
- Antoniotti, Sylvain,Blerot, Bernard,Chietera, Giorgiana,Lecourt, Mathilde
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supporting information
(2021/10/19)
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- Iridium-Catalyzed Asymmetric Allylic Alkylation of Deconjugated Butyrolactams
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Compared with the ever-growing list of nonprochiral nucleophiles in Ir-catalyzed asymmetric allylic substitution reactions, prochiral nucleophiles are less studied. We present a new prochiral nucleophile, namely, deconjugated butyrolactam, for Ir-catalyze
- Mitra, Sankash,Mukherjee, Santanu
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supporting information
p. 3021 - 3026
(2021/05/04)
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- [Pd]-Catalyzedpara-selective allylation of phenols: access to 4-[(E)-3-aryl/alkylprop-2-enyl]phenols
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4-[(E)-3-Arylprop-2-enyl]phenols are omnipresent scaffolds and constitute natural products and biologically significant compounds. Obtusastyrene and obtustyrene are two such phenolic-based natural products isolated fromDalbergia retusa. The development of strategies based on a site-selective allylation, particularly protecting group-free substrates and non-activated coupling agents, is indispensable in organic synthesis. Herein, we present a highly regioselective [Pd]-catalyzedpara-allylation of phenols using simple, inactivated allylic alcohols as allylating coupling partners. Notably, this strategy is successful in open-air and under mild reaction conditions. Besides, the efficacy of the present protocol was demonstrated by the direct synthesis of obtusastyrene and obtustyrene.
- Chinnabattigalla, Sreenivasulu,Choudhury, Aditya,Gedu, Satyanarayana
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supporting information
p. 8259 - 8263
(2021/10/12)
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- Highly efficient kinetic resolution of aryl-alkenyl alcohols by ru-catalyzed hydrogen transfer
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No matter through asymmetric reduction of ketones or kinetic resolution of secondary alcohols, enantioselective synthesis of the corresponding secondary alcohols is challenging when the two groups attached to the prochiral or chiral centers are spatially
- Jin, Ming Yu,Tao, Guanyu,Xing, Xiangyou,You, Yipeng
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supporting information
(2021/12/24)
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- Allylic and Allenylic Dearomatization of Indoles Promoted by Graphene Oxide by Covalent Grafting Activation Mode
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The site-selective allylative and allenylative dearomatization of indoles with alcohols was performed under carbocatalytic regime in the presence of graphene oxide (GO, 10 wt percent loading) as the promoter. Metal-free conditions, absence of stoichiometric additive, environmentally friendly conditions (H2O/CH3CN, 55 °C, 6 h), broad substrate scope (33 examples, yield up to 92 percent) and excellent site- and stereoselectivity characterize the present methodology. Moreover, a covalent activation model exerted by GO functionalities was corroborated by spectroscopic, experimental and computational evidences. Recovering and regeneration of the GO catalyst through simple acidic treatment was also documented.
- Lombardi, Lorenzo,Bellini, Daniele,Bottoni, Andrea,Calvaresi, Matteo,Monari, Magda,Kovtun, Alessandro,Palermo, Vincenzo,Melucci, Manuela,Bandini, Marco
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supporting information
p. 10427 - 10432
(2020/07/24)
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- Asymmetric Synthesis of γ-Secondary Amino Alcohols via a Borrowing-Hydrogen Cascade
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The borrowing-hydrogen (or hydrogen autotransfer) process, where the catalyst dehydrogenates a substrate and formally transfers the H atom to an unsaturated intermediate, is an atom-efficient and environmentally benign transformation. Described here is an example of an asymmetric borrowing-hydrogen cascade for the formal anti-Markovnikov hydroamination of allyl alcohols to synthesize optically enriched γ-secondary amino alcohols. By exploiting the Ru-(S)-iPrPyme catalyst with minimal stereogenicity, a cascade process including dehydrogenation, conjugate addition, and asymmetric reduction was developed. The mild conditions, functional group tolerance, and broad substrate scope (54 examples) demonstrate the synthetic practicality of the catalytic system.
- Chang, Xiaoyong,Chen, Fumin,He, Dongxu,Jin, Ming Yu,Pan, Yupeng,Xing, Xiangyou,You, Yipeng
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supporting information
p. 7278 - 7283
(2020/10/02)
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- 1,3-Dioxa-[3,3]-sigmatropic Oxo-Rearrangement of Substituted Allylic Carbamates: Scope and Mechanistic Studies
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An unexpected 1,3-dioxa-[3,3]-sigmatropic rearrangement during the treatment of aryl- and alkenyl-substituted allylic alcohols with activated isocyanates is reported. The reorganization of bonds is highly dependent on the electron density of the aromatic
- Agirre, Maddalen,Henrion, Sylvain,Rivilla, Ivan,Miranda, José I.,Cossío, Fernando P.,Carboni, Bertrand,Villalgordo, José M.,Carreaux, Fran?ois
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p. 14861 - 14881
(2019/01/04)
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- Isothiourea-Catalysed Acylative Kinetic Resolution of Aryl–Alkenyl (sp2vs. sp2) Substituted Secondary Alcohols
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The non-enzymatic acylative kinetic resolution of challenging aryl–alkenyl (sp2vs. sp2) substituted secondary alcohols is described, with effective enantiodiscrimination achieved using the isothiourea organocatalyst HyperBTM (1 mol %) and isobutyric anhydride. The kinetic resolution of a wide range of aryl–alkenyl substituted alcohols has been evaluated, with either electron-rich or naphthyl aryl substituents in combination with an unsubstituted vinyl substituent providing the highest selectivity (S=2–1980). The use of this protocol for the gram-scale (2.5 g) kinetic resolution of a model aryl–vinyl (sp2vs. sp2) substituted secondary alcohol is demonstrated, giving access to >1 g of each of the product enantiomers both in 99:1 e.r.
- Musolino, Stefania F.,Ojo, O. Stephen,Westwood, Nicholas J.,Taylor, James E.,Smith, Andrew D.
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supporting information
p. 18916 - 18922
(2016/12/26)
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- The synthesis and analysis of lignin-bound Hibbert ketone structures in technical lignins
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Understanding the structure of technical lignins resulting from acid-catalysed treatment of lignocellulosic biomass is important for their future applications. Here we report an investigation into the fate of lignin under acidic aqueous organosolv conditions. In particular we examine in detail the formation and reactivity of non-native Hibbert ketone structures found in isolated organosolv lignins from both Douglas fir and beech woods. Through the use of model compounds combined with HSQC, HMBC and HSQC-TOCSY NMR experiments we demonstrate that, depending on the lignin source, both S and G lignin-bound Hibbert ketone units can be present. We also show that these units can serve as a source of novel mono-aromatic compounds following an additional lignin depolymerisation reaction.
- Miles-Barrett, Daniel M.,Neal, Andrew R.,Hand, Calum,Montgomery, James R.D.,Panovic, Isabella,Ojo, O. Stephen,Lancefield, Christopher S.,Cordes, David B.,Slawin, Alexandra M.Z.,Lebl, Tomas,Westwood, Nicholas J.
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supporting information
p. 10023 - 10030
(2016/11/06)
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- A Mixed-Ligand Chiral Rhodium(II) Catalyst Enables the Enantioselective Total Synthesis of Piperarborenine B
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A novel, mixed-ligand chiral rhodium(II) catalyst, Rh2(S-NTTL)3(dCPA), has enabled the first enantioselective total synthesis of the natural product piperarborenine B. A crystal structure of Rh2(S-NTTL)3(dCPA) r
- Panish, Robert A.,Chintala, Srinivasa R.,Fox, Joseph M.
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supporting information
p. 4983 - 4987
(2016/04/26)
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- PHARMACEUTICAL COMPOSITIONS COMPRISING LIGNANS AND THEIR DERIVATIVES FOR TREATING HYPERPLASTIC DISEASES
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The present invention relates to a pharmaceutical composition comprising specific compounds which may be obtained from Leontopodium alpinum Cass. (Edelweiss). A preferred compound is leoligin (=(2S,3R,4R)-4-(3,4-dimethoxybenzyl) -2-(3,4-dimethoxyphenyl)tetrahydrofuran-3-yl]methyl(2Z)-2-methylbut-2-enoat]). Corresponding means and methods in respect of medical uses of the compounds are described. The present invention also provides a medical device comprising, containing or having been contacted with the compound. The compounds provided herein may particularly be used in the treatment of hyperplastic diseases, in particular intimal hyperplasia, e.g. stenosis, restenosis, atherosclerosis and the like. Also envisaged herein is the use of these compounds in the treatment of proliferative diseases, such as leukemia, prostate cancer and lung cancer.
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Page/Page column 48
(2016/11/07)
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- An organocatalytic asymmetric allylic alkylation allows enantioselective total synthesis of hydroxymetasequirin-a and metasequirin-b tetramethyl ether diacetates
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The first highly stereoselective organocatalytic intermolecular allylic alkylation of allylic alcohols with 1,3-dicarbonyls has been developed to allow the first enantioselective total synthesis of hydroxymetasequirin-A and metasequirin-B tetramethyl ethe
- Wang, Pu-Sheng,Zhou, Xiao-Le,Gong, Liu-Zhu
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supporting information
p. 976 - 979
(2014/03/21)
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- Synthesis of enantiopure 1-arylprop-2-en-1-ols and their tert-butyl carbonates
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(Chemical Equation Presented) Enantiomerically pure 1-arylpropenols 8 have been prepared by resolution of the corresponding racemates, using the lipase formulation Novozyme 435. Deprotonation of the latter alcohols with n-BuLi, followed by derivatization with (t- BuO)2CO, afforded the corresponding carbonates 5. Optimization of the process is presented.
- Stambasky, Jan,Malkov, Andrei V.,Kocovsky, Pavel
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supporting information; body text
p. 9148 - 9150
(2009/04/11)
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- cis-selective single-cleavage skeletal rearrangement of 1,6-enynes reveals the multifaceted character of the intermediates in metal-catalyzed cycloisomerizations
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A skeleton in the closet: The unprecedented title rearrangement of 1,6-enynes has been observed with gold and platinum catalysts (see scheme, [M] = metal catalyst, Z = C(CO2Me)2, R = electron-donating group). This reaction is propose
- Jimenez-Nunez, Eloisa,Claverie, Christelle K.,Bour, Christophe,Cardenas, Diego J.,Echavarren, Antonio M.
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supporting information; experimental part
p. 7892 - 7895
(2009/05/07)
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- Tetrahydrofuran lignans via tandem oxidative anionic-radical processes or reductive radical cyclizations
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Several tetrahydrofuran lignans have become important due to their diverse biological activities. We present initial studies on short syntheses of some of the simplest members of this natural product class. Galgravin and Veraguensin are obtained in only t
- Jahn, Ullrich,Rudakov, Dmytro
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p. 4481 - 4484
(2007/10/03)
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- Concise enantioselective synthesis of furan lignans (-)-dihydrosesamin and (-)-acuminatin and furofuran lignans (-)-sesamin and (-)-methyl piperitol by radical cyclization of epoxides
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Enantioselective syntheses of furan lignans (-)-dihydrosesamin and (-)-acuminatin and furofuran lignans (-)-sesamin and (-)-methyl piperitol were achieved in up to only three steps in 43%, 42%, 63%, and 60% overall yield, respectively, with high optical purity through stereoselective intramolecular radical cyclization of suitably substituted epoxy olefinic ethers using bis(cyclopentadienyl)titanium(III) chloride as the radical initiator. The key intermediate, chiral epoxy alcohol 4, was prepared by the Sharpless kinetic resolution method. The titanium(III) initiator was prepared in situ from commercially available titanocene dichloride and activated zinc dust in tetrahydrofuran. Georg Thieme Verlag Stuttgart.
- Banerjee, Biplab,Roy, Subhas Chandra
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p. 2913 - 2919
(2007/10/03)
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- A Versatile Stereoselective Synthesis of endo,exo-Furofuranones: Application to the Enantioselective Synthesis of Furofuran Lignans
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A new stereoselective route to endo,exo-2,6-diarylfurofuranones has been developed using Mn(III)-mediated intramolecular cyclopropanation and C-H insertion reactions as key C-C bond-forming steps. Mn(III)-mediated oxidative cyclization of acetoacetate derivative 11 afforded 1-acetyl-4-aryl-3-oxabicyclo[3.1.0]hexan-2-one (12) with excellent diastereocontrol (d.r. 22:1). Subsequent Lewis acid-catalyzed opening of the activated cyclopropane ring present in 12 with benzylic alcohols then gave α-acetyl-γ-butyrolactones 16 and 18-20, which reacted efficiently with in situ-generated TfN3 to secure the key α-diazo-γ -butyrolactones 22-25. Highly stereoselective rhodium-catalyzed C-H insertion reactions of diazolactones 22-25 completed the synthesis of endo,exo-2,6-diarylfurofuranones 26-29 in overall yields ranging from 41 to 48% from 1-phenylallyl alcohol (±)-10. The approach developed for the furofuranones 26-29 was then applied to the asymmetric syntheses of four furofuran lignans, (+)-xanthoxylol (1), (+)-methylxanthoxylol (2), (+)-epipinoresinol (3), and (+)-epieudesmin (4), starting from enantiomerically enriched 1-arylallyl alcohol (S)-31.
- Swain, Nigel A.,Brown, Richard C. D.,Bruton, Gordon
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p. 122 - 129
(2007/10/03)
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- Concise Synthesis of Dihydrochalcones via Palladium-Catalyzed Coupling of Aryl Halides and 1-Aryl-2-propen-1-ols
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An expedient route to substituted dihydrochalcones is reported. The key step is a palladium-assisted arylation of 1-aryl-2-propen-1-ols. This two-step/one-purification process allows the synthesis of a wide range of compounds with original substitution patterns, including polyphenolic derivatives.
- Briot, Anne,Baehr, Corinne,Brouillard, Raymond,Wagner, Alain,Mioskowski, Charles
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p. 1374 - 1377
(2007/10/03)
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- Substituted furans as inhibitors of the PDE4 enzyme
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The synthesis and in vitro activity of a series of substituted furans as a novel structural class of PDE4 inhibitors is described. Comparison of emetic threshold with known PDE4 inhibitors is presented.
- Perrier, Helene,Bayly, Christopher,Laliberte, France,Huang, Zheng,Rasori, Roberta,Robichaud, Annette,Girard, Yves,Macdonald, Dwight
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p. 323 - 326
(2007/10/03)
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