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Identification and optimization of novel pyrimido-isoxazolidine and oxazine as selective hydride donors
Two novel carbon skeletons (3S,3a′R)-6′-(methylthio)-5′, 7a′-dihydro-1′H-spiro[indoline-3,3′-isoxazolo[3,4-d] pyrimidine]-2,4′(3a′H)-dione (11a) and 3-(methylthio)-4a,5,7,11c- tetrahydropyrimido[4′,5′:3,4][1,2]oxazino[6,5-b]indol-1(2H)-one (12a) are characterized as hydride donors. The generation of these hydride sources during the spiroannulation reaction between isatin (4) and pyrimidine (5) through the free radical mechanism, was confirmed by (i) the increase in the stoichiometric yields of 11 and 12 when the same reaction was carried out in the presence of free radical initiators (e.g., mCPBA) and (ii) the formation of oxazepine (14) when AIBN was used as free radical initiator. The PKIE [K H/KD] values 4.5 and 4.9 obtained when deuterated 11a (d) was used in the presence of TFA and TFA-d, respectively, suggest the hydride transfer step to be the rate determining step. These hydrides donors selectively reduce aldehyde in the presence of other reducible groups.
Khan, Imran A.,Balaramnavar, Vishal M.,Saxena, Anil K.
p. 10122 - 10129,8
(2012)
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Syntheses of racemic and optically active 4-hydroxy-2-hydroxymethyl-1,7-dioxaspiro[5.5]undecanes
Racemic and optically active 4-hydroxy-2-hydroxymethyl-1,7-dioxaspiro[5.5]undecanes were prepared in six steps from butane-1,2,4-triol and valerolactone with the longest linear sequence being four steps.
Kaugars,Nelson,Dutton,Martin
p. 797 - 809
(1993)
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Sime3-based homologation-epoxidation-cyclization strategy for ladder THP synthesis
(Matrix presented) A trimethylsilyl (SiMe3) group is the basis of a strategy that emulates the three fundamental proposed processes in ladder polyether biosynthesis: chain homologation, stereoselective epoxidation (>95% ee or >95:5 dr), and endo-selective, stereospecific (inversion) hydroxyepoxide cyclization (>95:5 endo:exo, >95% dr). A tris-THP was synthesized in 18 total operations from commercial materials using this approach.
Heffron, Timothy P.,Jamison, Timothy F.
p. 2339 - 2342
(2003)
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GaCl3-Catalyzed Ring-Opening Carbonyl-Olefin Metathesis
The development of a Lewis acid-catalyzed ring-opening cross-metathesis reaction which enables selective access to acyclic, unsaturated ketones as the carbonyl-olefin metathesis products is described. While catalytic amounts of FeCl3 were previously identified as optimal to catalyze ring-closing metathesis reactions, the complementary ring-opening metathesis between cyclic alkenes and carbonyl functionalities relies on GaCl3 as the superior Lewis acid catalyst.
Albright, Haley,Vonesh, Hannah L.,Becker, Marc R.,Alexander, Brandon W.,Ludwig, Jacob R.,Wiscons, Ren A.,Schindler, Corinna S.
p. 4954 - 4958
(2018)
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Expansion of substrate scope for nitroxyl radical/copper-catalyzed aerobic oxidation of primary alcohols: A guideline for catalyst selection
Four distinctive sets of optimum nitroxyl radical/copper salt/additive catalyst combinations have been identified for accommodating the aerobic oxidation of various types of primary alcohols to their corresponding aldehydes. Interestingly, less nucleophilic catalysts exhibited higher catalytic activities for the oxidation of particular primary allylic and propargylic alcohols to give α,β-unsaturated aldehydes that function as competent Michael acceptors. The optimum conditions identified herein were successful in the oxidation of various types of primary alcohols, including unprotected amino alcohols and divalent-sulfur-containing alcohols in good-to-high yields. Moreover, N-protected alaninol, an inefficient substrate in the nitroxyl radical/ copper-catalyzed aerobic oxidation, was oxidized in good yield. On the basis of the optimization results, a guideline for catalyst selection has been established.
Iwabuchi, Yoshiharu,Nagasawa, Shota,Sasaki, Ryota,Sasano, Yusuke,Yamaichi, Aoto
p. 488 - 497
(2021/05/27)

(Cyclopentadienone)iron-Catalyzed Transfer Dehydrogenation of Symmetrical and Unsymmetrical Diols to Lactones
Air-stable iron carbonyl compounds bearing cyclopentadienone ligands with varying substitution were explored as catalysts in dehydrogenative diol lactonization reactions using acetone as both the solvent and hydrogen acceptor. Two catalysts with trimethylsilyl groups in the 2- A nd 5-positions, [2,5-(SiMe3)2-3,4-(CH2)4(δ4-C4C= O)]Fe(CO)3 (1) and [2,5-(SiMe3)2-3,4-(CH2)3(δ4-C4C= O)]Fe(CO)3 (2), were found to be the most active, with 2 being the most selective in the lactonization of diols containing both primary and secondary alcohols. Lactones containing five-, six-, and seven-membered rings were successfully synthesized, and no over-oxidations to carboxylic acids were detected. The lactonization of unsymmetrical diols containing two primary alcohols occurred with catalyst 1, but selectivity was low based on alcohol electronics and modest based on alcohol sterics. Evidence for a transfer dehydrogenation mechanism was found, and insight into the origin of selectivity in the lactonization of 1°/2° diols was obtained. Additionally, spectroscopic evidence for a trimethylamine-ligated iron species formed in solution during the reaction was discovered.
Tang, Yidan,Meador, Rowan I. L.,Malinchak, Casina T.,Harrison, Emily E.,McCaskey, Kimberly A.,Hempel, Melanie C.,Funk, Timothy W.
p. 1823 - 1834
(2020/02/04)

Selective oxidation of exogenous substrates by a bis-Cu(III) bis-oxide complex: Mechanism and scope
Cu(III)2(μ-O)2 bis-oxides (O) form spontaneously by direct oxygenation of nitrogen-chelated Cu(I) species and constitute a diverse class of versatile 2e?/2H+ oxidants, but while these species have attracted attention as biomimetic models for dinuclear Cu enzymes, reactivity is typically limited to intramolecular ligand oxidation, and systems exhibiting synthetically useful reactivity with exogenous substrates are limited. OTMPD (TMPD = N1, N1, N3, N3-tetramethylpropane-1,3-diamine) presents an exception, readily oxidizing a diverse array of exogenous substrates, including primary alcohols and amines selectively over their secondary counterparts in good yields. Mechanistic and DFT analyses suggest substrate oxidation proceeds through initial axial coordination, followed by rate-limiting rotation to position the substrate in the Cu(III) equatorial plane, whereupon rapid deprotonation and oxidation by net hydride transfer occurs. Together, the results suggest the selectivity and broad substrate scope unique to OTMPD are best attributed to the combination of ligand flexibility, limited steric demands, and ligand oxidative stability. In keeping with the absence of rate-limiting C–H scission, OTMPD exhibits a marked insensitivity to the strength of the substrate Cα–H bond, readily oxidizing benzyl alcohol and 1-octanol at near identical rates.
Large, Tao A.G.,Mahadevan, Viswanath,Keown, William,Stack, T. Daniel P.
p. 782 - 792
(2019/01/03)

Noncanonical cation-π cyclizations of alkylidene β-ketoesters: Synthesis of spiro-fused and bridged bicyclic ring systems
Three cation-π cyclization cascades initiated at alkylidene β-ketoesters bearing pendent alkenes are described. Depending upon the alkene substitution pattern and the reaction conditions employed, it is possible to achieve selective synthesis of the three different types of products, including 1-halo-3-carbomethoxycyclohexanes, spiro-fused tricyclic systems, and [4.3.1] bridged bicyclic ring systems. All three reactions begin with 6-endo addition of an olefin to the alkylidene β-ketoester electrophile, followed by one of three different cation capture events.
Parsons, Dylan E.,Frontier, Alison J.
supporting information
p. 2008 - 2012
(2019/03/26)

Revisiting Sodium Hypochlorite Pentahydrate (NaOCl·5H 2 O) for the Oxidation of Alcohols in Acetonitrile without Nitroxyl Radicals
Sodium hypochlorite pentahydrate (NaOCl·5H 2 O) is capable of oxidizing alcohols in acetonitrile at 20 °C without the use of catalysts. The oxidation is selective to allylic, benzylic, and secondary alcohols. Aliphatic primary alcohols are not oxidized.
Hirashita, Tsunehisa,Sugihara, Yuto,Ishikawa, Shota,Naito, Yohei,Matsukawa, Yuta,Araki, Shuki
p. 2404 - 2407
(2018/11/23)

Rhodium-Catalyzed Asymmetric Conjugate Alkynylation/Aldol Cyclization Cascade for the Formation of α-Propargyl-β-hydroxyketones
A rhodium-catalyzed conjugate alkynylation/aldol cyclization cascade was developed. Densely functionalized cyclic α-propargyl-β-hydroxyketones were synthesized with simultaneous formation of a C(sp)-C(sp3) bond, a C(sp3)-C(sp3) bond, as well as three new contiguous stereocenters. The transformation was achieved with excellent enantio- and diastereoselectivities using BINAP as the ligand. The synthetic utility of the newly installed alkynyl moiety was exhibited by subjecting the products to an array of derivatizations.
Choo, Ken-Loon,Lautens, Mark
supporting information
p. 1380 - 1383
(2018/03/09)

Chemoselective continuous-flow hydrogenation of aldehydes catalyzed by platinum nanoparticles dispersed in an amphiphilic resin
A chemoselective continuous-flow hydrogenation of aldehydes catalyzed by a dispersion of platinum nanoparticles in an amphiphilic polymer (ARP-Pt) has been developed. Aromatic and aliphatic aldehydes bearing various reducible functional groups, such as keto, ester, or amide groups, readily underwent flow hydrogenation in aqueous solutions within 22 s in a continuous-flow system containing ARP-Pt to give the corresponding primary benzylic or aliphatic alcohols in ≤99% yield with excellent chemoselectivity. Moreover, the long-term continuous-flow hydrogenation of benzaldehyde for 8 days was realized, and the total turnover number of the catalyst reached 997. The flow hydrogenation system provides an efficient and practical method for the chemoselective hydrogenation of aldehydes bearing reducible functional groups.
Osako, Takao,Torii, Kaoru,Hirata, Shuichi,Uozumi, Yasuhiro
p. 7371 - 7377
(2017/11/09)

2-AMINO-1,3,4-THIADIAZINE AND 2-AMINO-1,3,4-OXADIAZINE BASED ANTIFUNGAL AGENTS
The invention provides a compound which is a diazine of formula (I) or a tautomer thereof, or a pharmaceutically acceptable salt thereof, for use as an antifungal agent: (I) wherein X, N', C', A and E are as defined herein. The invention also provides a compound of Formula (I) as defined herein.
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Page/Page column 118

(2017/02/09)

Development of Fluorinated Analogues of Perhexiline with Improved Pharmacokinetic Properties and Retained Efficacy
We designed and synthesized perhexiline analogues that have the same therapeutic profile as the parent cardiovascular drug but lacking its metabolic liability associated with CYP2D6 metabolism. Cycloalkyl perhexiline analogues 6a-j were found to be unsuitable for further development, as they retained a pharmacokinetic profile very similar to that shown by the parent compound. Multistep synthesis of perhexiline analogues incorporating fluorine atoms onto the cyclohexyl ring(s) provided a range of different fluoroperhexiline analogues. Of these, analogues 50 (4,4-gem-difluoro) and 62 (4,4,4′,4′-tetrafluoro) were highly stable and showed greatly reduced susceptibility to CYP2D6-mediated metabolism. In vitro efficacy studies demonstrated that a number of derivatives retained acceptable potency against CPT-1. Having the best balance of properties, 50 was selected for further evaluation. Like perhexiline, it was shown to be selectively concentrated in the myocardium and, using the Langendorff model, to be effective in improving both cardiac contractility and relaxation when challenged with high fat buffer.
Tseng, Chih-Chung,Noordali, Hannah,Sani, Monica,Madhani, Melanie,Grant, Denis M.,Frenneaux, Michael P.,Zanda, Matteo,Greig, Iain R.
supporting information
p. 2780 - 2789
(2017/04/21)

Characterization of Aroma-Active Compounds in Italian Tomatoes with Emphasis on New Odorants
An aroma distillate was prepared by solvent extraction and subsequent SAFE distillation from Italian vine-ripe tomatoes eliciting an intense overall aroma. Application of gc/olfactometry and the aroma extract dilution analysis revealed 44 odor-active compounds, 42 of which could be identified. The highest odor activity value of 2048 was established for the green, grassy (Z)-3-hexenal, the metallic smelling trans-4,5-epoxy-(E)-2-decenal, the potato-like 3-(methylthio)propanal, and the caramel-like 4-hydroxy-2,5-dimethyl-3(2H)-furanone. Of the further odorants, 13 compounds have previously not been reported as tomato odorants. Although most of these showed lower FD-factors, in particular, the coconut/dill-like smelling wine lactone ((3S,3aS,7aR)-3a,4,5,7a-tetrahydro-3,6-dimethylbenzofuran-2(3H)-one) appeared with a quite high FD factor. In addition, a fruity, almond-like odorant (6) with an FD factor of 1024 was detected. By application of high resolution mass spectrometry and polarity considerations, the structure of a methyl-2-ethoxytetrahydropyran isomer was suggested for 6. Four of the five possible isomers, the 3-methyl-, 4-methyl-, 5-methyl-, and 6-methyl-2-ethoxytetrahydropyran were synthesized and showed similar mass spectrometric patterns. However, these were excluded by their different retention indices. Although the synthesis of the remaining 2-methyl-2-ethoxytetrahydropyran resulted in only small yields, which were not sufficient for NMR measurements, this structure is very likely for 6. This compound was never reported as a food constituent before. Finally, quantitation of 23 odorants by stable isotope dilution assays allowed for the preparation of an aroma recombinate resembling the overall aroma of the tomatoes.
Kreissl, Johanna,Schieberle, Peter
p. 5198 - 5208
(2017/07/04)

METHODS OF PRODUCING COMPOUNDS FROM 5-(HALOMETHYL)FURFURAL
Provided herein are methods of producing compounds, such as cyclohexanone, hexanediamine, hexanediol, hexamethylenediamine, caprolactam and nylon, from 5-(halomethyl)furfural.
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Paragraph 0161; 0164

(2016/10/09)

Water-Soluble Gold-N-Heterocyclic Carbene Complexes for the Catalytic Homogeneous Acid- and Silver-Free Hydration of Hydrophilic Alkynes
Water-soluble gold(III/I) N-heterocylic carbene complexes behave as efficient catalysts for the hydration of terminal alkynes in neat water. The transformation proceeds in the absence of Bronsted acids or halide scavengers and is suitable for sensitive substrates. Kinetic profiles and DFT studies provide a clear picture of intermediates present during catalysis.
Ibrahim, Houssein,Defrmont, Pierre,Braunstein, Pierre,Thry, Vincent,Nauton, Lionel,Cisnetti, Federico,Gautier, Arnaud
p. 3893 - 3900
(2016/01/25)

METHODS OF PRODUCING COMPOUNDS FROM 5-(HALOMETHYL)FURFURAL
Provided herein are methods of producing compounds, such as cyclohexanone, hexanediamine, hexanediol, hexamethylenediamine, caprolactam and nylon, from 5- (halomethyl)furfural.
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Paragraph 0164

(2016/04/26)

One-pot synthesis of micro/nano structured β-Bi2O3 with tunable morphology for highly efficient photocatalytic degradation of methylparaben under visible-light irradiation
β-Bi2O3 micro/nanostructures with tunable morphologies were synthesized via a one-pot solvothermal-calcining route, and their photocatalytic activity toward degrading methylparaben (MeP, a widely used preservative with estrogenic activity) was evaluated under visible-light (λ ≥ 420 nm) irradiation. The formation process of β-Bi2O3 catalysts can be described as reduction of Bi3+ through a solvothermal reaction, followed by oxidization of metal Bi via calcination in air. During this process, the organic reductants (single or a mixture of ethylene glycol, d-fructose, and ascorbic acid) play important roles in determining the final morphologies and structures of the materials. Photocatalytic tests reveal that MeP can be effectively degraded and mineralized by using synthetic β-Bi2O3 catalysts, and the reaction rate constant of an optimum sample is more than 25 and 160 times faster than a commercial Bi2O3 and synthetic N-TiO2, respectively. The superior photocatalytic activity of the optimum product is ascribed to its pure beta phase with a narrower band gap, good absorption of visible light, more efficient separation of electrons and holes, relatively higher BET specific surface area, and three-dimensional architectures, which favor more surface active sites and easier mass and photoinduced charge transportations. In addition, the main reactive oxygen species and possible degradation intermediates were detected, and the results suggest that photogenerated holes and superoxide radicals are the predominant species in the photochemical oxidation process.
Xiao, Xin,Hu, Ruiping,Tu, Shunheng,Zheng, Chunxia,Zhong, Huan,Zuo, Xiaoxi,Nan, Junmin
p. 38373 - 38381
(2015/07/28)

DIHYDROOROTIC ACID DEHYDROGENASE INHIBITOR
The present invention provides a novel dihydroorotic acid dehydrogenase inhibitor which is applicable to various diseases. When used as an active ingredient, a compound represented by formula (I): (wherein X represents a halogen atom, R1 represents a hydrogen atom, R2 represents an alkyl group containing 1 to 7 carbon atoms, R3 represents -CHO, and R4 represents -CH2-CH=C(CH3)-R0 (wherein R0 represents an alkyl group containing 1 to 12 carbon atoms which may have a substituent on the terminal carbon and/or on a non-terminal carbon, etc.)), an optical isomer thereof or a pharmaceutically acceptable salt thereof has a high inhibitory effect on dihydroorotic acid dehydrogenase and can be used as an immunosuppressive agent, a therapeutic agent for rheumatism, an anticancer agent, a therapeutic agent for graft rejection, an antiviral agent, an anti-H. pylori agent, a therapeutic agent for diabetes or the like.
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Paragraph 0253; 0254

(2015/04/15)

NOVEL DIHYDROXYBENZENE DERIVATIVES AND ANTIPROTOZOAL AGENT COMPRISING SAME AS ACTIVE INGREDIENT
Novel compounds below are useful for preventing or treating diseases caused by protozoans. At least one of a compound represented by Formula (I) (wherein, X represents a hydrogen atom or a halogen atom; R1 represents a hydrogen atom; R2 represents a hydrogen atom or a C1-7 alkyl group; R3 represents -CHO, -C(=O)R5, -COOR5 (wherein R5 represents a C1-7 alkyl group), -CH2OH or -COOH; and R4 represents a C1-16 alkyl group having one or more substituents on a terminal carbon atom and/or non-terminal carbon atom(s), a C2-16 alkenyl group having one or more substituents on a terminal carbon atom and/or non-terminal carbon atom(s), or a C2-16 alkynyl group having one or more substituents on a terminal carbon atom and/or non-terminal carbon atom(s)), an optical isomer thereof, and a pharmaceutically acceptable salt is used.
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Paragraph 0263; 0264

(2013/09/26)

AgOTf catalyzed hydration of terminal alkynes
The silver catalysis towards the hydration of terminal alkynes is explored using Silver(I) triflate (AgOTf). The reaction leads to the formation of only Markovnikov addition product with excellent yield. Copyright
Das, Rima,Chakraborty, Debashis
p. 722 - 726
(2013/02/22)

Cu(II)-Catalyzed Olefin Migration and Prins Cyclization: Highly Diastereoselective Synthesis of Substituted Tetrahydropyrans
Metal-ligand complexes of Cu(OTf)2 with an appropriate bisphosphine ligand have been shown to effectively catalyze the formation of substituted tetrahydropyrans via a sequential olefin migration and Prins-type cyclization. This methodology provides convenient access to a variety of functionalized tetrahydropyrans in excellent diastereoselectivities and good to excellent yields.
Ghosh, Arun K.,Nicponski, Daniel R.
supporting information; experimental part
p. 4328 - 4331
(2011/10/05)

Na4H3[SiW9Al3(H2O)3O37]·12H2O/H2O: a new system for selective oxidation of alcohols with H2O2 as oxidant
This work describes a catalytic system consisting of both Na4H3[SiW9Al3(H2O)3O37]·12H2O(SiW9Al3) and water as solvents (a?small quantity of organic solvents were used as co-solvent for a few substrates) that can be good for selective oxidation of alcohols to ketones (aldehydes) using 30% H2O2 without any phase-transfer catalyst under mild reaction conditions. The catalyst system allows easy product/catalyst separation. Under the given conditions, the secondary hydroxyl group was highly chemoselectively oxidized to the corresponding ketones in good yields in the presence of primary hydroxyl group within the same molecule, and hydroxides are selectively oxidized even in the presence of alkene. Benzylic alcohols were selectively oxidized to the corresponding benzaldehydes in good yields without over oxidation products in solvent-free conditions. Nitrogen, oxygen, sulfur-based moieties, at least for the cases where these atoms are not susceptible to oxidation, do not interfere with the catalytic alcohol oxidation.
Wang, Jianmin,Yan, Liang,Qian, Guang,Li, Shunqing,Yang, Keli,Liu, Haitao,Wang, Xiaolai
p. 1826 - 1832
(2007/10/03)

Regio- and stereoselective reduction of diketones and oxidation of diols by biocatalytic hydrogen transfer
The asymmetric reduction of symmetrical and nonsymmetrical diketones as well as the stereoselective oxidation of various diols by biocatalytic hydrogen transfer was investigated by employing lyophilized cells of Rhodococcus ruber DSM 44541 containing alcohol dehydrogense ADH-'A'. Symmetrical and nonsymmetrical diketones at the (ω-1)- and (ω-2)-positions are reduced to the Prelog product with high stereopreference, while sterically more demanding ketone moieties, for example those at the (ω-3)-position, remain unchanged. For the oxidation mode, differentiation between primary and secondary alcohols is achieved, and the (S)-configured secondary alcohols at the (ω-1)- and (ω-2)-positions are oxidized preferentially. Wiley-VCH Verlag GmbH & Co. KGaA, 2006.
Edegger, Klaus,Stampfer, Wolfgang,Seisser, Birgit,Faber, Kurt,Mayer, Sandra F.,Oehrlein, Reinhold,Hafner, Andreas,Kroutil, Wolfgang
p. 1904 - 1909
(2007/10/03)

A facile access to bridged 1,2,4-trioxanes
Bicyclo[3.2.1] type 1,2,4-trioxanes are readily synthesized from precursors that may form intramolecular hemiketals using UHP (H2O2-urea complex) as the source of the peroxy bond and p-TsOH or CSA as the catalyst. The ring closure through an intramolecular Michael addition occurred in a highly stereoselective way, giving only one diasteromer as shown by the NMR spectra.
Zhang, Qi,Jin, Hong-Xia,Wu, Yikang
p. 11627 - 11634
(2007/10/03)

Process for producing carbonyl compound
The present invention relates to a process which comprises efficiently proceeding a hydration reaction of an alkyne in aspects of turnover numbers of a catalyst, yield and speed to thereby industrially and advantageously produce the corresponding carbonyl compound. The present invention provides a process for producing a carbonyl compound, which comprises reacting an alkyne compound with water in the presence of a gold catalyst which is an organogold complex compound and acid in an organic solvent.
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(2008/06/13)

Stereocontrol of 1,5-related stereocentres using an intermediate silyl group-the diastereoselectivity of nucleophilic attack on a double bond adjacent to a stereogenic carrying a silyl group
R-5-Methylcyclohex-2-enone 1 reacts successively with the phenyldimethylsilylzincate reagent and acetaldehyde to give with regiocontrol the aldols 7, dehydration of which creates the E-exocyclic double bond of the α-β-unsaturated ketone 2. Conjugate addition of the ethylcuprate reagent to this compound takes place with high (96 : 4) selectivity in favour of the R stereoisomer 12, hydrolysis of which gives (2R,3R,5S,2′ R)-2-(but-2′-yl)-3-dimethyl(phenyl)silyl-5-methylcyclohexanone 3. The oxime acetate of this ketone undergoes fragmentation in the presence of trimethylsilyl trifluoromethanesulfonate to give 3R,7R,5E-3,7-dimethylnon-5-enonitrile 4, in which an open-chain 1,5-stereo-chemical relationship is set up with a high level of stereocontrol. A similar sequence adding 4-methylpentylcuprate to the enone 2, and fragmentation gives 3R,7R,5E-3,7,11-trimethyldodec-5-enonitrile 20. Reduction and hydrogenation of this nitrile gives 3R,7R-3,7,11 -trimethyldodecanal 22, which can be converted into phytol 25. The ketoaldehyde 29 reacts with samarium iodide to give only the alcohol 30, in which the radical anion has attacked from the top surface, just like the cuprate reagents in their reactions with the ketone 2.
Fleming, Ian,Maiti, Pranab,Ramarao, Chandrashekar
p. 3989 - 4004
(2007/10/03)

Highly efficient Au1-catalyzed hydration of alkynes
As good as gold: Hydration of alkynes by using gold - acid catalyst systems with high turnover frequencies provides a greener synthetic route to carbonyl compounds in high yields, as shown.
Mizushima, Eiichiro,Sato, Kazuhiko,Hayashi, Teruyuki,Tanaka, Masato
p. 4563 - 4565
(2007/10/03)

Catalytic Conversions in Water. Part 21: Mechanistic Investigations on the Palladium-Catalysed Aerobic Oxidation of Alcohols in Water
Water-soluble complexes of palladium(II) with phenanthroline-derivatives are stable, recyclable catalysts for the selective aerobic oxidation of a wide range of alcohols to aldehydes, ketones, and carboxylic acids in a biphasic liquid-liquid system. The active catalyst is a dihydroxy-bridged palladium dimer. Kinetics of the reaction, ligand and anion effects are discussed.
Ten Brink, Gerd-Jan,Arends, Isabel W. C. E.,Sheldon, Roger A.
p. 355 - 369
(2007/10/03)

Mercuric triflate-TMU catalyzed hydration of terminal alkyne to give methyl ketone under mild conditions
Herein developed mercuric triflate-TMU catalyzed hydration of terminal alkyne is a mild procedure to give methyl ketone in excellent yield with high chemoselectivity. By using 0.05 eq of Hg(OTf)2·(TMU)2 and 3 eq of water, hydration takes place at a reasonable rate in acetonitrile.
Nishizawa, Mugio,Skwarczynski, Mariusz,Imagawa, Hiroshi,Sugihara, Takumichi
p. 12 - 13
(2007/10/03)

Methods for attachment of a polynucleotide to a preselected material
Compositions and methods for selectively linking a polynucleotide through its 5' or 3' end to one or more preselected materials such as insoluble matrices, solid supports, proteins, small molecular or labels are disclosed. Use of these compositions and methods in the production of diagnostic and affinity reagents are also disclosed.
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(2008/06/13)

Selective hydroboration of alkenes and alkynes in the presence of aldehydes and ketones
The reactions of terminal alkenes in the presence of ketones or aldehydes with a variety of borane reagents have been investigated. It was found that the selective hydroboration of a terminal alkene in the presence of a ketone or an aldehyde is most efficient when dicyclohexylborane is used as the hydroborating agent. The hydroboration of olefinic ketones and olefinic aldehydes with dicyclohexylborane generates the corresponding hydroxyaldehydes and hydroxyketones in good yields after oxidation with sodium perborate. The hydroboration of alkynyl ketones and alkynyl aldehydes with dicyclohexylborane yields the corresponding olefinic carbonyl compounds after protonation, or dicarbonyl compounds after oxidation.
Kabalka, George W.,Yu, Su,Li, Nan-Sheng
p. 800 - 805
(2007/10/03)

Selective hydroboration of terminal alkenes in the presence of aldehydes and ketones
The hydroboration of olefinic ketones and aldehydes with dicyclohexylborane gives the corresponding hydroxy aldehydes and ketones in good yields after oxidation with sodium perborate.
Kabalka, George W.,Yu, Su,Li, Nan-Sheng
p. 5455 - 5458
(2007/10/03)

Selective Oxidation of Diols by H2O2/TS-1 System and by DMDO.
Selective oxidations of secondary hydroxyl groups vs. primary ones in 1,n-diols by TS-1/H2O2 catalitic system and by dimethyldioxirane, new reagents with low environmental pollution, are reported.
Bovicelli, Paolo,Lupattelli, Paolo,Sanetti, Anna,Mincione, Enrico
p. 8477 - 8480
(2007/10/02)

18-Cycloalkyl Analogues of Enisoprost
By use of standard cuprate methodology, a series of 18-cycloalkyl analogues of enisoprost was prepared in an effort to impede ω chain metabolism and prolong duration of gastric antisecretory activity.An initial product of ω chain oxidation, the C-20 hydroxy analogue, was also synthesized for pharmacological comparison.The cyclopropyl, cyclobutyl, and cyclopentyl analogues were approximately one-fourth as potent as enisoprost in inhibiting gastric acid secretion, while the cyclohexyl and cycloheptyl analogues showed very weak activity, and the 20-hydroxy compound was inactive at a dose 100 times the ED 50 of enisoprost.The cyclobutyl compound had a longer duration of antisecretory action than enisoprost and the other cycloalkyl analogues.The cycloalkyl analogues unexpectedly possessed low diarrheogenic activity in rats.
Collins, Paul W.,Gasiecki, Alan F.,Perkins, Willam E.,Gullikson, Gary W.,Jones, Peter H.,Bauer, Raymond F.
p. 1001 - 1006
(2007/10/02)

Oxidative Cleavage of Carbon-Silicon Bonds by Dioxygen: Catalysis by a Flavin-Dihydronicotinamide Redox System
Carbon-silicon bonds in alkyloxy- or fluoro-silanes readily undergo cleavage by dioxygen (molecular oxygen), catalysed by tetra-acetylriboflavin (5-10 molpercent) in the presence of N-benzyl-1,4-dihydronicotinamide as reductant, together with fluoride ions as an essential additive.
Tamao, Kohei,Hayashi, Takashi,Ito, Yoshihiko
p. 795 - 797
(2007/10/02)

Detection and determination of 3,7-dimethyl-6-(5-oxo-hexoxy)-2h-purine-2-ones, a by-product of pentoxifylline synthesis
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Proksa,Michalak,Nevydal
p. 429 - 430
(2007/10/02)

Thiol esters in organic synthesis. X. A new approach to 1,5-ketols and 5-hydroxy esters using S,S'-diethyl dithiomalonate as an ethanol carbanion equivalent
Michael addition of S,S'-diethyl dithiomalonate to conjugated enones and α,β-unsaturated esters followed by reduction with Raney-nickel gave rise to 1,5-ketols and 5-hydroxy esters respectively in good yields.
Liu, Hsing-Jang,Oppong, Isaac V.
p. 94 - 96
(2007/10/02)

Antimalarials. 13. 5-Alkoxy Analogues of 4-Methylprimaquine
A series of nuclear and side-chain analogues of 4-methylprimaquine incorporating an alkoxy group in 5-position of the quinoline nucleus has been prepared.The compounds were tested for suppresive antimalarial activity against Plasmodium berghei in mice and for radical curative antimalarial activity against Plasmodium cynomolgi in the rhesus monkey.Although the toxicity problems characteristic of the 8-aminoquinolines were not overcome, several of the compounds, suprisingly, were highly effective as both blood and tissue schizonticidal agents.
LaMontage, Maurice P.,Markovac, Anica,Khan, M. Sami
p. 964 - 968
(2007/10/02)