- An improved synthesis of methyl (E)-5-nitro-2-pentenoate
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A two-step synthesis of methyl (E)-5-nitro-2-pentenoate involving addition of nitrous acid to acrolein followed by Wittig olefination is described. The preparation can be routinely carried out on a 0.1 mole scale to afford the title compound in 45-50% overall yield as a 92:8 mixture of the E:Z double bond isomers.
- Bunce,Parker
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Read Online
- Asymmetric Synthesis of 2,3,4-Trisubstituted Piperidines
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Two different organocatalytic approaches for the asymmetric synthesis of 2,3,4-trisubstituted piperidines were developed. Both approaches were based on an aza-Michael addition followed by cyclization and gave products in high enantiomeric excess.
- Kriis, Kadri,Melnik, Triin,Lips, Kristiina,Juhanson, Ilona,Kaabel, Sandra,J?rving, Ivar,Kanger, T?nis
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supporting information
p. 604 - 614
(2017/01/25)
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- Quinine-Based Trifunctional Organocatalyst for Tandem Aza-Henry Reaction-Cyclization: Asymmetric Synthesis of Spiroxindole-Pyrrolidine/Piperidines
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A quinine-derived trifunctional sulphonamide catalyst has been developed for the effective asymmetric organocatalytic tandem aza-Henry reaction-cyclization of isatin-derived ketimines and nitroalkane-mesylates for the synthesis of spiro-pyrrolidine/piperidine-oxindoles. Demethylation of traditional bifunctional catalyst to incorporate an additional hydrogen bonding C6′-OH group plays the key role toward remarkable enantioselectivity.
- Hajra, Saumen,Jana, Bibekananda
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supporting information
p. 4778 - 4781
(2017/09/23)
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- Catalytic Asymmetric Synthesis of Isoxazolines from Silyl Nitronates
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1,3-Dipolar cycloadditions of triisopropylsilyl nitronates and 2-alkylacroleins produced isoxazolines bearing a chiral quaternary center in high yields and enantioselectivities with the aid of a chiral oxazaborolidine catalyst. One chiral isoxazoline product was converted to (R)-(+)-Tanikolide in 9 steps in a total yield of 43%. (Chemical Equation Presented).
- Han, Xiaoyu,Dong, Li,Geng, Caiwei,Jiao, Peng
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supporting information
p. 3194 - 3197
(2015/07/15)
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- Oxidative Amidation of Nitroalkanes with Amine Nucleophiles using Molecular Oxygen and Iodine
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The formation of amides and peptides often necessitates powerful yet mild reagent systems. The reagents used, however, are often expensive and highly elaborate. New atom-economical and practical methods that achieve such goals are highly desirable. Ideally, the methods should start with substrates that are readily available in both chiral and non-chiral forms and utilize cheap reagents that are compatible with a wide variety of functional groups, steric encumberance, and epimerizable stereocenters. A direct oxidative method was developed to form amide and peptide bonds between amines and primary nitroalkanes simply by using I2 and K2CO3 under O2. Contrary to expectations, a 1:1 halogen-bonded complex forms between the iodonium source and the amine, which reacts with nitronates to form α-iodo nitroalkanes as precursors to the amides.
- Li, Jing,Lear, Martin J.,Kawamoto, Yuya,Umemiya, Shigenobu,Wong, Alice R.,Kwon, Eunsang,Sato, Itaru,Hayashi, Yujiro
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supporting information
p. 12986 - 12990
(2015/11/02)
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- Pyrrolo[2,1-c][1,4]naphthodiazepine Linked Piperazine Compounds and a Process for the Preparation Thereof
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The present invention provides a compound of general formula A, useful as potential antitumour agents against five human cancer cell lines. The present invention further provides a process for the preparation of pyrrolo[2,1-c][1,4]naphthodiazepine linked substituted piperazine conjugates attached through different alkane spacers of general formula A. (Formula I) General formula A. Where R=R′=(Formula II). n=1-9 and R″=methyl, ethyl, acetyl, benzyl, piperinoyl, 4-fluorophenyl, 4-chlorophenyl, 4-methoxyphenyl, pyridyl, pyrimidyl
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Paragraph 0270
(2013/12/04)
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- Synthetic studies on statins. Part 1: A short and cyanide-free synthesis of atorvastatin calcium via an enantioselective aldol strategy
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A short and cyanide-free enantioselective synthesis of atorvastatin calcium has been achieved starting from a commercially available highly substituted 1,4-diketone in an overall yield of 40%. The key step in this approach is the asymmetric aldol reaction of an aldehyde with diketene in the presence of Ti(O-i-Pr)4-Schiff base complex to create the (5R)-stereochemistry of atorvastatin calcium.
- Hu, Lemeng,Xiong, Fangjun,Chen, Xiaofei,Chen, Wenxue,He, Qiuqin,Chen, Fener
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p. 207 - 211
(2013/04/10)
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- NUCLEIC ACID BINDING COMPOUNDS, METHODS OF MAKING, AND USE THEREOF
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The present invention relates to oligomer compounds, including dimers and trimers, formed by a disulfide, sulfinyl thio, olefin or hydrocarbon bond, or a hydrazone exchange bond between two or more monomers. Methods of making the monomers and the oligomers is also disclosed. Use of the compounds for inhibiting the activity of target RNA molecules, particularly those having a secondary structure that include a stem or stem-loop formation. Dimer compounds capable of inhibiting the activity of an HIV-1 RNA frameshifting stem-loop and a (CUG)n expanded repeat stem- loop are disclosed, as are methods of treating diseases associated with these target RNA molecules.
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Page/Page column 45-46
(2012/07/14)
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- PYRROLO [2,1-C]1,4]NAPHTHODIAZEPINE LINKED PIPERAZINE COMPOUNDS AND A PROCESS FOR THE PREPARATION THEREOF
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The present invention provides a compound of general formula A, useful as potential antitumour agents against five human cancer cell lines. The present invention further provides a process for the preparation of pyrrolo[2,1-c][1,4]naphthodiazepine linked substituted piperazine conjugates attached through different alkane spacers of general formula A. (Formula I) General formula A. Where R= R'= (Formula II). n=1-9 and R''= methyl, ethyl, acetyl, benzyl, piperinoyl, 4-fluorophenyl, 4-chlorophenyl, 4-methoxyphenyl, pyridyl, pyrimidyl
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Page/Page column 41-42
(2012/09/10)
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- Synthesis of 3-nitropropanol homologues
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Several high yielding routes to oxygenated nitropropanes have been developed that include a palladium catalyzed nitro allylation of allylic carbonates, nitration of brominated compounds and a nitro aldol condensation/hydrogenation sequence. Georg Thieme Verlag Stuttgart.
- Addo, James K.,Teesdale-Spittle, Paul,Hoberg, John O.
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p. 1923 - 1925
(2007/10/03)
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- Arylmethyl radicals from arylmethoxybromodiazirines
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(Chemical Equation Presented) Photolytic decompositions of 3-arylmethoxy-3-bromodiazirines afford arylmethyl radicals by homolyses of the diazirines' excited states.
- Moss, Robert A.,Fu, Xiaolin
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p. 3353 - 3356
(2007/10/03)
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- Reactions of hydroxylated sodium nitronates with acetic anhydride/pyridine
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Reactions with Ac2O/Py of sodium nitronate salts derived from primary or secondary nitroalkanes bearing hydroxyl groups at γ or more remote positions have been studied. In all cases, the results could be explained through an acetic nitronic anhydride intermediate, whose evolution depends on conformational factors, and also on the type of the hydroxyl group.
- Berrocal,Gil,Román,Serrano
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p. 5327 - 5333
(2007/10/03)
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- An expeditious synthesis of 3-nitropropionic acid and its ethyl and methyl esters
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The synthesis to 3-nitropropionic acid 1 was easily accomplished, in two steps, from commercially available acrolein in 60% yield. The ethyl and methyl esters of 1 were also obtained.
- Silva,Costa,Pereira
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p. 595 - 600
(2007/10/03)
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- Formal Synthesis of (+)- and (-)-Perhydrohistrionicotoxin: A "Double Henry"/Enzymatic Desymmetrization Route to the Kishi Lactam
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Both antipodes of the Kishi lactam (3), the versatile intermediate for the synthesis of the perhydrohistrionicotoxin (pHTX) alkaloids, have been prepared. The synthetic route involved a "double Henry" condensation between glutaraldehyde and nitroacetal 5 giving meso dioxanyldiol 4 which was acetylated and reduced to afford meso dioxane amide 8. Ultrasound-promoted deacetalization of 8 followed by Wittig olefination and reduction provided meso amide ester 10. Hydrolysis of 10 with aqueous acid followed by dehydrative cyclization with dicyclohexylcarbodiimide gave lactamdiol 11. Acetylation of 11 gave meso diacetate 2 which was an excellent substrate for esterase-mediated hydrolysis to hydroxyacetate 12. Deoxygenation of 12 using a Barton protocol, followed by Zemplen deacylation and Swern oxidation, gave the (-)-antipode of the Kishi lactam (3). Moffatt oxidation of hydroxyacetate 12 followed by ketal protection and Zemplen deacylation gave ketalalcohol 19. Barton deoxygenation of 19 followed by ketal hydrolysis gave (+)-3.
- Luzzio, Frederick A.,Fitch, Richard W.
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p. 5485 - 5493
(2007/10/03)
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- Regioselective synthesis of 5-unsubstituted benzyl pyrrole-2-carboxylates from benzyl isocyanoacetate
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A general synthesis of 5-unsubstituted benzyl pyrrole-2-carboxylates was developed based on the reaction of β-nitroacetates with benzyl isocyanoacetate. The advantage of this route over other pyrrole syntheses was the regiochemical control of the substitution pattern on the pyrrole ring.
- Ono,Katayama,Nisyiyama,Ogawa
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p. 707 - 710
(2007/10/02)
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- 4-Isopropyl-2-oxazolin-5-one anion as a new convenient formyl anion equivalent for conjugate addition and aldol reactions
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The anion of the title compound, simply generated in the presence of catalytic amount of triethylamine, acts as nucleophilic acylating equivalent of formaldehyde reacting with both common electrophilic olefins or aldehydes to give moderate to good yield of Michael or aldol adducts respectively, which are easily hydrolized by dilute acid at ambient to temperature to afford the corresponding aldehydes.
- Barco, Achille,Benetti, Simonetta,De Risi, Carmela,Pollini, Gian P.,Spalluto, Giampiero,Zanirato, Vinicio
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p. 3907 - 3910
(2007/10/02)
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- 3-Nitropropanal and 3-Nitropropanol: Preparation of the Parent Compounds and Derivatives
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3-Nitropropanal has been prepared for the first time by 1,4-nitrite addition to acrolein.Several acetals of 3-nitropropanal are described, as well as 3-nitropropanol and some of its ethers. 3-Nitropropanol has been obtained by borane-dimethyl sulfide reduction of both 3-nitropropanal and 3-nitropropanoic acid.These reactions make available a variety of nitro compounds known as, or expected to become, highly useful and versatile building blocks for organic syntheses.
- Oehrlein, Reinhold,Schwab, Wilfried,Ehrler, Rudolf,Jaeger, Volker
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p. 535 - 538
(2007/10/02)
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