- Visible-light mediated facile dithiane deprotection under metal free conditions
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Visible light mediated facile and selective dithiane deprotection under metal free conditions is developed. Eosin Y (1 mol%) proved to be an effective catalyst for the dithiane deprotection under the ambient photoredox conditions. The standard household compact fluorescent light source (CFL bulb) proved to be effective under open-air conditions in aqueous acetonitrile at room temperature. The protocol that exhibits a broad substrate scope and functional group tolerance has been shown to expand to a range of transformations for the electron-rich and -deficient thioacetals and thioketals. The synthetic utility of this protocol has also been demonstrated by gram-scale application.
- Dharpure, Pankaj D.,Bhowmick, Anindita,Warghude, Prakash K.,Bhat, Ramakrishna G.
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- Dehydrative Glycosylation Enabled by a Comproportionation Reaction of 2-Aryl-1,3-dithiane 1-Oxide?
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A new dehydrative glycosylation reaction has been established by capitalizing on the comproportionation reaction of 2-aryl-1,3-dithiane 1-oxides promoted by triflic anhydride (Tf2O). By wedding the high potency of thiophilic promoter system with the step efficiency of dehydrative glycosylation, this reagent underwent facile intermolecular oxothio acetalization with C1-hemiacetal donor to install a temporary leaving group, rendering a transient electrophilic center at the remote site to the anomeric position. The sulfenyl triflate tethered at the terminus concomitantly activated the sulfide intramolecularly to afford the oxocarbenium ion, thereby facilitating the title glycosylation. Aside from accommodating broad range functional groups and inactive hemiacetal substrates, the present activation protocol also proved expedient for 1,3-diol protection. Most importantly, this method further provided a fresh perspective for the application of sulfur chemistry to carbohydrate chemistry.
- Cai, Lei,Zeng, Jing,Li, Ting,Xiao, Ying,Ma, Xiang,Xiao, Xiong,Zhang, Qin,Meng, Lingkui,Wan, Qian
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supporting information
p. 43 - 49
(2019/11/28)
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- Design, synthesis, and evaluation of DNA topoisomerase II-targeted nucleosides
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We developed novel nucleoside-based topoisomerase II selective inhibitors and showed that small structural units, such as catechols, are essential for DNA topoisomerase II inhibitory activity. Moreover, nucleoside analogues containing TBS and 1,3-dithian
- Matsumoto, Hironobu,Yamashita, Mitsuaki,Tahara, Teruyuki,Hayakawa, Shinya,Wada, Shun-ichi,Tomioka, Kiyoshi,Iida, Akira
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p. 4133 - 4144
(2017/07/05)
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- Design and synthesis of novel arctigenin analogues for the amelioration of metabolic disorders
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Analogues of the natural product (-)-arctigenin, an activator of adenosine monophosphate activated protein kinase, were prepared in order to evaluate their effects on 2-deoxyglucose uptake in L6 myotubes and possible use in ameliorating metabolic disorders. Racemic arctigenin 2a was found to display a similar uptake enhancement as does (-)-arctigenin. As a result, the SAR study was conducted utilizing racemic compounds. The structure-activity relationship study led to the discovery of key substitution patterns on the lactone motif that govern 2-deoxyglucose uptake activities. The results show that replacement of the para-hydroxyl group of the C-2 benzyl moiety of arctigenin by Cl has a pronounced effect on uptake activity. Specifically, analogue 2p, which contains the p-Cl substituent, stimulates glucose uptake and fatty acid oxidation in L6 myotubes.
- Duan, Shudong,Huang, Suling,Gong, Jian,Shen, Yu,Zeng, Limin,Feng, Ying,Ren, Wenming,Leng, Ying,Hu, Youhong
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supporting information
p. 386 - 391
(2015/04/27)
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- Synthesis of chiral α-diarylacetic esters by stereospecific 1,2-aryl migration promoted by in situ generated acetals from benzoins
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A simple protocol for the synthesis of α-diarylacetic esters from benzoins is described. In situ generated acetal assists rapid 1,2-aryl migration in a stereospecific manner, paving the way to make enantioenriched α-diarylacetic esters from easily accessi
- Kothapalli, Raveendra Babu,Niddana, Ramana,Balamurugan, Rengarajan
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supporting information
p. 1278 - 1281
(2014/04/03)
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- Synthesis of (+)-septicine using intramolecular McMurry coupling: A Chiron approach
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Total synthesis of secophenanthroindolizidine alkaloid (+)-septicine 1 was accomplished using the McMurry coupling for the construction of indolizidine ring, using L-glutamicacid as chiral source. Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications to view the free supplemental file.
- Reddy, K. Umamaheshwar,Reddy, A. Panasa
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supporting information
p. 2678 - 2684
(2013/07/26)
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- Silica-supported phosphorus pentoxide: A reusable catalyst for S,S-acetalization of carbonyl groups under ambient conditions
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Phosphorus pentoxide supported on silica gel (P2O 5/SiO2) efficiently acts as a highly active and reusable catalyst for cyclic and non-cyclic S,S-acetalization of a variety of carbonyl compounds under mild, solvent-free an
- Shaterian, Hamid Reza,Azizi, Kobra,Fahimi, Nafiseh
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experimental part
p. 85 - 91
(2012/01/06)
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- Oxidative deprotection of 1,3-dithiane group using NaClO2 and NaH2PO4 in aqueous methanol
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The 1,3-dithiane group was oxidatively deprotected under the conditions of sodium chlorite, sodium dihydrogenphosphate, and 2-methyl-2-butene in 3:1 methanol-water at room temperature in good yield.
- Ichige, Takahiro,Miyake, Annu,Kanoh, Naoki,Nakata, Masaya
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p. 1686 - 1690
(2007/10/03)
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- Chemoselective thioacetalisation and transthioacetalisation of carbonyl compounds catalysed by tetrabutylammonium tribromide (TBATB)
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Thioacetals and thioketals of various aldehydes and ketones were obtained directly from carbonyl compounds or by a transthioacetalisation process from cyclic O,O-acetals in the presence of dithiols and a catalytic amount of tetrabutylammonium tribromide (TBATB). Chemoselective thioacetalisation of aromatic aldehydes containing an electron-donating group in the presence of an aldehyde containing an electron-withdrawing group, aldehydes in the presence of ketones, aliphatic cyclic ketones in the presence of aromatic ketones and less hindered ketones in the presence of more hindered ketones have been achieved. A cyclic acetal containing an electron-donating group has been chemoselectively transthioacetalised in the presence of an acetal having an electron-withdrawing substituent. These selectivities are due to the intrinsic reactivity of the substrate themselves and are independent of the catalyst and reaction conditions, Shorter reaction times, mild reaction conditions, stability of acid sensitive protecting groups, high efficiencies, facile isolation of the desired products and the catalytic nature of the reagent are the attractive features of the present method.
- Naik, Sarala,Gopinath, Rangam,Goswami, Mousumi,Patel, Bhisma K.
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p. 1670 - 1677
(2007/10/03)
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- Synthesis of acylsilanes via oxidative hydrolysis of 2-silyl-1,3-dithianes mediated by N-bromosuccinimide
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The oxidative method for the hydrolysis of 1,3-dithianes was applied to 2-silyl-1,3-dithianes using N-bromosuccinimide providing acylsilanes with good yields under a short reaction period. The oxidation of aroylsilanes to carboxylic acid was prevented by
- Patrocínio, Amauri F.,Moran, Paulo J.S.
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p. 220 - 224
(2007/10/03)
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- Enantioselective synthesis of a-hydroxysilanes by bioreduction of aroyltrimcthylsilanes
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Aromatic acylsilanes [Ar-CO-SiMe3; Ar = C6H5,4-ClC6H4, 2-, 3- and 4-OMeC6H4, 3,4-(OMe)2C6H3 and 3,4-OCH2OC6H3] were reduced by baker's yeast to optically active a-silyl alcohols in 20-70% yield and 43-88% ee. Comments are made on the influence of silicon in this bioreduction reaction. The Royal Society of Chemistry 1999.
- Patrocinio, Amauri F.,Correa Jr., Ivan R.,Moran, Paulo J. S.
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p. 3133 - 3137
(2007/10/03)
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- A silver salt - iodine reagent system for the deprotection of monothioacetals and dithioacetals
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A new reagent (silver salt - iodine) system was developed for the deprotection of monothioacetals and dithioacetals. The reactions using this reagent system afforded the parent carbonyl compounds in moderate to quantitative yields under mild conditions. T
- Nishide, Kiyoharu,Nakamura, Daisaku,Yokota, Kouichi,Sumiya, Toshio,Node, Manabu,Ueda, Masaru,Fuji, Kaoru
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p. 393 - 404
(2007/10/03)
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- Synthesis of dibenzylbutyrolactone lignans: Total synthesis of arctigenin, pluviatolide and haplomyrfolin by tandem conjugate addition
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The total synthesis of three dibenzylbutyrolactone lignans, arctigenin, pluviatolide and haplomyrfolin has been carried out by tandem cnjugate addition of dithiane carbanions to but-2-en-4-olide and substituted benzyl bromides leading to the formation of key intermediates which subsequently underwent debenzylation and desulphurisation.
- Mitra, Jayati,Mitra, Alok Kumar
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p. 953 - 956
(2007/10/02)
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- Photochemistry of a model lignin compound. spin trapping of primary products and properties of an oligomer
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α-Guaiacoxylacetoveratrone, 1, was selected as a model of a lignin structure component for photolysis and free radical spin trapping studies. The 3,4-dimethoxyphenacyl radical, Ar-COCH2, 2, thermally generated from α-bromoacetoveratrone with tr
- Barclay,Cromwell,Hilborn
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- Synthetic entry into the secoisoquinoline alkaloids
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Several analogs of secoisoquinolinc alkaloids bearing a dimethylaminoethyl side chain and a benzilic, or reduced benzilic group were synthesized. Two independent methods based on the intermediacy of 1,3-dithians and O-benzoylated cyanohydrins as acyl anio
- Rozwadowska,Chrzanowska
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p. 2885 - 2890
(2007/10/02)
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- Justicidin insecticidal and antiviral compounds
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A natural lignan of the 1-aryl-2-napthoic acid type and related compounds are disclosed. The compounds correspond to the formula STR1 and exhibit both insecticidal and antiviral activity.
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