6090-00-2Relevant academic research and scientific papers
Asymmetric total syntheses of (–)-ar-turmerone, (–)-dihydro-ar-turmerone, (–)-ar-dehydrocurcumene, and (–)-ar-himachalene via a key allylic oxidative rearrangement
Khatua, Arindam,Pal, Souvik,Das, Mrinal K.,Bisai, Vishnumaya
, (2021)
A Nature inspired strategy to oxidized aromatic bisabolanes has been envision from naturally occurring 2-methyl-6-(4′-methylphenyl)-3-hepten-2-ol (2a). The key methodology utilized in this synthesis is the allylic oxidative rearrangement following a [3,3]-sigmatropic rearrangement (Dauben oxidation) of tertiary allylic alcohol of natural product 2a. The enantioselectivity of 2a has been introduced via a Rh(I)-(S)-BINAP catalyzed p-tolylboronic acid addition onto E-ethylcrotonate. Thus, the total syntheses of (–)-ar-turmerone (1a), (-)-dihydro-ar-turmerone (1b) and (-)-ar-himachalene (3) has been achieved only in 6–7 steps.
Concise asymmetric total syntheses of (?)-nuciferol, (?)-nuciferal, and (?)-dihydrocurcumene via Rh(I)-catalyzed boronic acid addition
Pal, Souvik,Khatua, Arindam,Das, Mrinal K.,Bisai, Vishnumaya
supporting information, (2021/01/25)
A general catalytic asymmetric total synthesis of aromatic bisabolane sesquiterpenes, (?)-nuciferol (ent-1c), (?)-nuciferal (ent-1d), and (?)-dihydrocurcumene (ent-1h) have been achieved in 5–6 steps in high chemical yields from commercially available (E)
Asymmetric Umpolung Hydrogenation and Deuteration of Alkenes Catalyzed by Nickel
Guo, Siyu,Wang, Xiuhua,Zhou, Jianrong Steve
supporting information, p. 1204 - 1207 (2020/02/04)
Nickel-catalyzed asymmetric hydrogenation of several types of alkenes proceeds in high enantioselectivity, using acetic acid or water as the hydrogen source and indium powder as electron donor. The scope of alkenes herein include α,β-unsaturated esters, n
Nickel-catalyzed asymmetric transfer hydrogenation of conjugated olefins
Guo, Siyu,Yang, Peng,Zhou, Jianrong
supporting information, p. 12115 - 12117 (2015/07/28)
Asymmetric transfer hydrogenation of electron-deficient olefins is realized with nickel catalysts supported by strongly σ-donating bisphosphines. Deuterium labeling experiments point to a reaction sequence of formate decarboxylation, asymmetric hydride in
Highly enantioselective iridium-catalyzed hydrogenation of α,β-unsaturated esters
Li, Jia-Qi,Quan, Xu,Andersson, Pher G.
supporting information, p. 10609 - 10616 (2012/11/07)
α,β-Unsaturated esters have been employed as substrates in iridium-catalyzed asymmetric hydrogenation. Full conversions and good to excellent enantioselectivities (up to 99 % ee) were obtained for a broad range of substrates with both aromatic- and aliphatic substituents on the prochiral carbon. The hydrogenated products are highly useful as building blocks in the synthesis of a variety of natural products and pharmaceuticals. Asymmetric hydrogenation: A variety of α,β-unsaturated esters were hydrogenated with high enantioselectivities (see scheme). The hydrogenated products have been used in synthetic transformations as well as in formal total syntheses. Copyright
Lipase catalysed kinetic resolutions of 3-aryl alkanoic acids
Deasy, Rebecca E.,Brossat, Maude,Moody, Thomas S.,Maguire, Anita R.
, p. 47 - 61 (2011/04/18)
Hydrolase catalysed kinetic resolutions leading to a series of 3-aryl alkanoic acids (≥94% ee) are described. Hydrolysis of the ethyl esters with a series of hydrolases was undertaken to identify biocatalysts that yield the corresponding acids with excellent enantiopurity in each case. Steric and electronic effects on the efficiency and enantioselectivity of the biocatalytic transformation were also explored.
Baker's yeast mediated enantioselective synthesis of the bisabolane sesquiterpenes curcumene, turmerone, dehydrocurcumene and nuciferal
Fuganti, Claudio,Serra, Stefano,Dulio, Andrea
, p. 279 - 282 (2007/10/03)
Fermenting baker's yeast converts the allylic alcohol 6 into enantiomerically pure (S)-(+)-3-(p-tolyl)butan-1-ol 7 which is a useful chiral building block for the synthesis of bisabolane sesquiterpenes. The versatility of this approach is shown in the preparation of (S)-(+)-curcumene, (S)-(+)-turmerone, (S)-(+)-dehydrocurcumene and (E,S)-(+)-nuciferal.
REACTIONS OF ARYLAZO ARYL SULFONES WITH α,β-UNSATURATED ESTERS AND KETONES CATALYZED BY PALLADIUM(0) COMPLEX
Kamigata, Nobumasa,Satoh, Akira,Yoshida, Masato
, p. 121 - 130 (2007/10/02)
The palladium(0) catalyzed reactions of arylazo aryl sulfones (1) with α,β-unsaturated esters in benzene give aryl-substituted esters as major products and hydroarylated esters as minor products.The reactions of 1 with acyclic α,β-unsaturated ketones give considerable amounts of hydroarylated ketones and aryl-substituted ketones under similar conditions, whereas the reactions of 1 with cyclic α,β-unsaturated ketones afforded selectively hydroarylated compounds and no formation of aryl-substituted ketones was found.A plausible reaction mechanism is proposed.Key words: Arylazo aryl sulfones; palladium(0) catalyst; arylation; α,β-unsaturated carbonyl compounds; diarylpalladiumII) intermediate; catalytic cycle.
Rhodium-catalyzed isomerization of 1,3-diene monoepoxides to α,β-unsaturated carbonyl compounds
Sato, Susumu,Matsuda, Isamu,Izumi, Yusuke
, p. 255 - 266 (2007/10/02)
α,β-Unsaturated aldehydes and ketones are readily formed by the rhodium(I) catalyzed isomerization of 1,3-diene monoepoxides.When RhH(PPh3)4 is used as a catalyst, only (E)-α,β-unsaturated carbonyl compounds are obtained selectively.The initial 1,3-diene monoepoxides are prepared regiospecifically from α-trimethylsilyl ketones by a two step procedure, bromination and subsequent vinylative epoxidation of resulting α-bromo ketones.The overall transformation from α-trimethylsilyl ketones to α,β-enones is formally regarded as an equivalent of the regiospecific aldol condensation, and also enables the use of unsymmetrically substituted ketones as an enolate source.The significance of the isomerization as a key step in the synthesis of ar-turmerone is described.
