- Diastereoselective Desymmetrization of p-Quinamines through Regioselective Ring Opening of Epoxides and Aziridines
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A highly diastereoselective desymmetrization of p-quinamines via regioselective ring opening of epoxides and aziridines under mild conditions has been developed. A chairlike six-membered transition state with minimized 1,3-diaxial interactions explains the relative stereoselectivity of the cyclization reaction. This transition-metal free [3 + 3] annulation reaction provides rapid access to fused bicyclic morpholines and piperazines with a tetrasubstituted carbon center in high yields. In addition, it also allows the synthesis of enantioenriched products by using easily accessible chiral nonracemic epoxides and aziridines.
- Jadhav, Sandip B.,Chegondi, Rambabu
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supporting information
p. 10115 - 10119
(2019/12/24)
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- Prepartion method of itraconazole
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The invention discloses a preparation method of itraconazole. Raceme-glycidol which is cheap and easy to obtain is adopted as raw materials, hydroxyls at the two ends are protected by trityl and benzyl and then esterified by 2,4-dichlorobenzene formyl chloride, then, a silylation Grignard addition reaction and a beta-silicyl alcohol elimination reaction are adopted for reducing carbonyl into carbon-carbon double bonds, iodine is adopted for performing an olefin addition reaction and a stereoselectivity ring-closure reaction, triazole replacement and debenzylation are performed, and tosyl is introduced to obtain a compound 9; the compound and a compound 10 are subjected to a condensastion reaction to obtain itraconazole; the overall synthesis process is small in pollution, easy to process, few in by-product, high in reaction selectivity and purity, environmentally friendly, low in production cost and suitable for industrial production; the defects that in the prior art, the selectivity is poor, multiple by-products are produced, the yield is low, and expensive catalysts and reagents with large environmental pollution are avoided are avoided.
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Paragraph 0043; 0044; 0045; 0046
(2017/04/29)
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- Modular synthesis of dihydroxyacetone monoalkyl ethers and isosteric 1-hydroxy-2-alkanones
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Straightforward methods for the efficient, systematic preparation of libraries of the title compound classes have been evaluated. A general and efficient modular route to dihydroxyacetone monoethers was developed based on trityl glycidol, which, through epoxide opening, oxidation, and deprotection, provided variously alkylated ethers by three routine operations in good overall yields (eight examples, 24-59 %). The preparation of structurally related 1-hydroxyalkanones depends on the availability of the most economic starting materials and on their physicochemical properties. Thus, the most practical one-step approaches consisted of the sec-selective oxidation of short-chain 1,2-diols (≤ C6) using NaOCl, and the direct ketohydroxylation of 1-alkenes (≥ C6) using buffered stoichiometric KMnO4 or catalytic RuO4 with reoxidation by oxone, for which mostly good overall yields were achieved on a multigram scale (nine examples, 15-78 %).
- Güclü, Deniz,Rale, Madhura,Fessner, Wolf-Dieter
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supporting information
p. 2960 - 2964
(2015/04/27)
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- A straightforward approach to substituted 2-(hydroxymethyl)-2,3- dihydrofuro[2,3- b ]pyridines and 3-hydroxy-3,4-dihydro-2 H -pyrano[2,3- b ]pyridines
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An efficient route to 2-(hydroxymethyl)-2,3-dihydrofuro[2,3-b]pyridines and 3-hydroxy-3,4-dihydro-2H-pyrano[2,3-b]pyridines is reported. The strategy is based on an intramolecular inverse electron demand Diels-Alder reaction starting from 1,2,4-triazines.
- Hajbi, Youssef,Suzenet, Franck,Khouili, Mostafa,Lazar, Said,Guillaumet, Gerald
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experimental part
p. 1349 - 1355
(2010/07/02)
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- Total synthesis of solandelactones A, B, E, and F exploiting a tandem petasis-claisen lactonization strategy
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(Chemical Equation Presented) Solandelactones A, B, E, and F were synthesized using Nozaki-Hiyama-Kishi coupling of iododiene 13 with aldehydes 14 and 99 obtained by oxidation of alcohols 92 and 94. Key steps in the synthesis of 92 and 94 were (i) a Nagao asymmetric acetate aldol reaction of aldehyde 77 with thionothiazolidine 78 to set in place an alcohol that becomes the (75) lactone center of solandelactones, (ii) a Simmons-Smith cyclopropanation of 80 directed by this alcohol, and (iii) Petasis methylenation of cyclic carbonate 90 in tandem with a Claisen rearrangement that generates the octenalactone portion of solandelactones. Synthesis of solandelactones A, B, E, and F confirmed their gross structure and absolute configuration at C7, 8, 10, and 14 but showed that alcohol configuration at C11 must be reversed in pairs, A/B and E/F, from the previous assignment made to these hydroid metabolites. Thus, solandelactones A and B are correctly represented by 2 and 1, respectively, whereas solandelactones E and F are 6 and 5. A biogenesis of solandelactones is proposed for these C22 oxylipins that parallels a hypothesis put forward previously to explain the origin of C20 cyclopropane-containing algal products.
- White, James D.,Lincoln, Christopher M.,Yang, Jongtae,Martin, William H. C.,Chan, David B.
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p. 4139 - 4150
(2008/09/20)
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- Enantioselective incorporation of carbon dioxide into epoxides catalyzed by optically active cobalt(II) complexes
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The enantioselective chemical fixation of CO2 into an epoxide was developed using an optically active ketoimi-natocobalt(II) complex as a chiral Lewis acid. In the presence of a catalytic amount of the cobalt complex and amine base, enantioselective CO2 fixation with an epoxide proceeded with kinetic resolution to afford the corresponding carbonate along with unreacted epoxide, both of which were optically active. To improve their enantioselectivities, the ligand structures of the cobalt complexes and amine bases were examined. Thus, the optimized catalytic system was successfully applied to various epoxides to obtain the corresponding optically active cyclic carbonates and to recover epoxides with good-to-high enantioselectivities.
- Yamada, Wataru,Kitaichi, Yasunori,Tanaka, Hirotaka,Kojima, Tomohide,Sato, Mitsuo,Ikeno, Taketo,Yamada, Tohru
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experimental part
p. 1391 - 1401
(2009/06/20)
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- Effect of allylic and homoallylic substituents on cross metathesis: syntheses of prostaglandins F2α and J2
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We describe the effect of allylic (C15) and homoallylic (C11) substituents on cross metathesis reactions with Corey lactone derivatives. This strategy has led to the successful syntheses of PGF2α and PGJ2.
- Sheddan, Neil A.,Arion, Vladimir B.,Mulzer, Johann
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p. 6689 - 6693
(2007/10/03)
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- Synthesis of iso-epoxy-amphidinolide N and des-epoxy-caribenolide i structures. Initial forays
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Two strategies for the projected total synthesis of the phenomenally potent antitumour macrolides amphidinolide N (1) and caribenolide I (2) are described. The title compounds are introduced as challenging and unique targets for chemical synthesis, and their retrosynthetic analysis is presented. The synthesis of the four defined key building blocks (10, 39, 67 and 72), required for the construction of amphidinolide N (1), in their enantiomerically pure forms, is described, followed by the coupling of 10, 39 and 72 through hydrazone alkylation processes to generate the complete C6-C29 carbon framework of the target compound (1). Fusion of the remaining C1-C5 sector (72) onto the molecule by metathesis-based methods was unsuccessful, resulting in the adoption of a second-generation strategy which called for the employment of one of the array of palladium-catalysed cross-coupling reactions to generate the C5-C6 carbon-carbon bond. Vinyl bromide 125, representing the C6-C29 skeleton of caribenolide I (2), was prepared through the sequential alkylation of hydrazone 10 with bromide 116 and iodide 55, but failed to engage in the appropriate cross-coupling reaction with a variety of C1-C4 partners. Despite these setbacks, the information gleaned from these endeavours was to prove invaluable in laying the foundation for the eventual successful approach to the macrocyclic structures of amphidinolide N (1) and caribenolide I (2). The Royal Society of Chemistry 2006.
- Nicolaou,Brenzovich, William E.,Bulger, Paul G.,Francis, Tasha M.
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p. 2119 - 2157
(2008/02/07)
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- Lipase-mediated resolution of 3-hydroxy-4-trityloxybutanenitrile: synthesis of 2-amino alcohols, oxazolidinones and GABOB
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Lipase-mediated kinetic resolution of 3-hydroxy-4-trityloxybutanenitrile gave the (S)-alcohol and (R)-acetate in good yields and high enantioselectivities. The resolution using Pseudomonas cepacia lipase (Burkholderia cepacia) immobilized on modified cera
- Kamal, Ahmed,Khanna, G.B. Ramesh,Krishnaji,Ramu
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p. 1281 - 1289
(2007/10/03)
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- Cyclization strategies for the synthesis of macrocyclic bisindolylmaleimides
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Three new approaches to the synthesis of macrocyclic bisindolylmaleimides 1-4 have been identified. Two strategies afford 8, the penultimate intermediate for the synthesis of 1-4, in 73% and 32% yield by intramolecular cyclization of 31 and 40, respectively. The optimum synthesis of 1 was achieved in nine steps and 15% yield by intramolecular formation of the macrocycle and maleimide in one step by reaction of the sodium indolate of 12 with methyl indole-3-glyoxylate 47. The mechanism of this reaction has been elucidated, using the trityl-protected derivative, to involve initial formation of the tricarbonyl imide 48, followed by irreversible alkylation of the indole nitrogen to generate the 17-membered macrocycle 49. Cyclization of 49 to hydroxymaleimide 50 and subsequent dehydration afforded 8a. This approach eliminated the problem of dimerization observed in the intramolecular cyclization reactions.
- Faul,Krumrich
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p. 2024 - 2033
(2007/10/03)
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- Synthesis, biodistribution, and primate imaging of fluorine-18 labeled 2β-carbo-1'-fluoro-2-propoxy-3β-(4-chlorophenyl)tropanes. Ligands for the imaging of dopamine transporters by positron emission tomography
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2β-(R)-Carbo-1-fluoro-2-propoxy-3β-(4-chlorophenyl)tropane ((R)-FIPCT, R-6) and 2β-(S)-carbo-1-fluoro-2-propoxy-3β-(4-chlorophenyl)tropane ((S)- FIPCT, S-6) were prepared and evaluated in vitro and in vivo for dopamine transporter (DAT) selectivity and sp
- Xing, Dongxia,Chen, Ping,Keil, Robert,Kilts, Clinton D.,Shi, Bing,Camp, Vernon M.,Malveaux, Gene,Ely, Timothy,Owens, Michael J.,Votaw, John,Davis, Margaret,Hoffman, John M.,BaKay, Roy A. E.,Subramanian, Thygarajan,Watts, Ray L.,Goodman, Mark M.
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p. 639 - 648
(2007/10/03)
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- Synthesis and Absolute Configuration of a Novel Aminoglycoglycerolipid, Species-Specific Major Immunodeterminant of Mycoplasma fermentans
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In order to determine the absolute configuration of a novel aminoglycoglycerolipid isolated from Mycoplasma fermentans, the possible two diastereomers were stereoselectively synthesized by using (S)- and (R)-glycidols as the key building block. Their 1H-1H-cosy spectra compared with those of the natural product allowed us to determine the absolute configuration of the glycolipid. - Keywords: amino-alcohols; glycolipids; immunodeficiency; phospholipids; phosphoramidites
- Nishida, Yoshihiro,Takamori, Yusuke,Ohrui, Hiroshi,Ishizuka, Ineo,Matsuda, Kazuhiro,Kobayashi, Kazukiyo
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p. 2371 - 2374
(2007/10/03)
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- Formulations and methods for generating active cytofectin: polynucleotide transfection complexes
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In the generation of cytofectin:polynucleotide complexes for transfection of cells, formulations, counterions, and reaction conditions for maximizing the transfection include using a cationic amine compound that has the general structure: STR1 wherein Rs
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- Polyfunctional cationic cytofectins, formulations and methods for generating active cytofectin: polynucleotide transfection complexes
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Amine containing compounds and their use in the generation of cytofectin:polynucleotide complexes for transfection of cells, formulations, counterions, and reaction conditions for maximizing the transfection include using cationic amine compounds that hav
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- Insight into Rh(I)-catalyzed cyclization of 6-octen-1-als with a chiral protecting group
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Rh(I)(Wilkinson)[ClRh(PPh3)3]-catalyzed cyclization of 6-octen-als with a chiral protecting group at the C2-position afforded only cis-cyclohexanol derivatives, and in the case of C4-position yielded a mixture of cis and trans cyclohexanol. These findings were remakably different from the case of the C3-position, in which the trans cyclohexanol derivative was obtained. Wilkinson's complex acts as [ClRh(PPh3)3] a Lewis acid, and this bulkier Lewis acid affords higher diastereoselectivity. Rh(I)-catalyzed cyclization of 6-octen-1-al derivatives is not affected by chiral ligands.
- Koga,Funakoshi,Matsuda,Sakai
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p. 1857 - 1868
(2007/10/02)
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