Base-catalyzed Degradations of Carbohydrates. IV. Formation of 2,3-Anhydro-2-methoxy-α-D-allopyranose Derivatives from 3-Deoxy-D-erythro-hex-2-enopyranoses

1973 ◽  
Vol 51 (3) ◽  
pp. 394-401 ◽  
Author(s):  
G. O. Aspinall ◽  
R. R. King
Keyword(s):  
Spectroscopic Data ◽  
Kojic Acid ◽  
Major Product ◽  
A Minor

1,4,6-Tri-O-acetyl-3-deoxy-2-O-methyl-α-D-erythro-hex-2-enopyranose (4) reacts with m-chloroperbenzoic acid to give the epoxide, 1,4,6-tri-O-acetyl-2,3-anhydro-2-methoxy-α-D-allopyranose (6), as the major product together with the perester, 4,6-di-O-acetyl-1,2-O-(1′-m-chloroperbenzoyloxy-ethylidene)-2-methoxy-α-D-glucopyranose (5), as a minor product. The structures of these novel compounds have been assigned on the basis of spectroscopic data and of transformations (i) to kojic acid diacetate and (ii) by oxidative degradations to substituted aldopentonolactones. Further examination of the products of the reaction of 1-O-acetyl-3-deoxy-2,4,6-tri-O-methyl-α-D-erythro-hex-2-enopyranose (1) with m-chloroperbenzoic acid has shown that the epoxide, 1-O-acetyl-2,3-anhydro-2-methoxy-4,6-di-O-methyl-α-D-allopyranose (15), is formed in addition to the previously characterized perester 2.

scholarly journals Zur Reaktion von (CO)4FeP(R)Cl2 mit Na2Cr2(CO)10 / Reactions of (CO)4FeP(R)Cl2 with Na2Cr2(CO)10

1986 ◽  
Vol 41 (5) ◽  
pp. 532-540 ◽  
Author(s):  
Jutta Borm ◽  
Konrad Knoll ◽  
Laszlo Zsolnai ◽  
Gottfried Huttner
Keyword(s):  
Spectroscopic Data ◽  
Minor Component ◽  
Major Product ◽  
High Yield ◽  
Analogous Reaction ◽  
X Ray ◽  
A Minor

(CO)4FeP(R)Cl2 reacts with Na2Cr2(CO)10 to give the μ3 RP capped trigonal heterom etallic closed cluster Fe(CO)3Cr(CO)4Cr(CO)5(μ3-PR)(1) as a major product. ACr(CO)5-derivative of a metal substituted phosphane [(μ2(tBuPCl)Fe2(CO)7)(tBuPH)]Cr(CO)5 (2) is obtained as a minor component.The analogous reaction with (CO)4FeP(Ph)Cl2 only gives the known cluster Fe3(CO)9(μ3-PR)2 (3), while (CO)4FeP(c-hexyl)Cl2 results in 4, a pentacarbonylchromiumderivative of the diiron species Fe2(CO)6μ-(PR)3. Species o f this type, containing an Fe2(CO)6 entity doubly bridged by μ2-PR entities, which are them selves linked by another PR-group, are obtained in a systematic high yield process by reacting Fe2(CO)6(μ2-RPH)2 with n-BuLi/TMEDA , RPCl2. For com pound identification, analytical and spectroscopic data as well as four X-ray analyses are presented.

Nucleophilic addition at u 3 -alkyne clusters leading to carbon-carbon bond formation

1982 ◽  
Vol 308 (1501) ◽  
pp. 59-66 ◽  
Keyword(s):  
Bond Formation ◽  
Organic Ligand ◽  
Major Product ◽  
Unsaturated Hydrocarbon ◽  
Terminal Alkynes ◽  
Hydrogen Atoms ◽  
Metal Atoms ◽  
Carbon Carbon Bond ◽  
Anionic Species ◽  
A Minor

Reactions of nucleophiles with triosmium carbonyl clusters, especially those containing unsaturated hydrocarbon ligands, are discussed. Attack may be at CO, the metal atoms, at carbon of the organic ligand, or, where there are acidic metal-bound hydrogen atoms, deprotonation to give anionic clusters may occur. New results on the reactions of LiBHEt3 with p3-alkyne clusters of type Os3(CO)10 (RC2R') are considered in the light of the range of possible sites of attack. Protonation of anionic species that are formed gives hydrogenation products with or without the loss of CO. Os3H2(CO)9(RC2R') is usually a minor product, while C-C coupling leads to Os3H(CO)9(CRCR'COH) (in general the major product) and to Os3H(CO)9- (CRCR'CH). With terminal alkynes RC2H H-atom transfer accompanies C-C coupling to give Os3H(CO)9(RC—C =C H 2) in substantial amounts. The initial site of hydride attack (CO, alkyne or metal) is considered in the context of low-temperature 1H n.m.r. results.

Transition metal complexes of substituted alkynes. XI. The reactions of But-2-yne and Hexafluorobut-2-yne with Dicarbonyl(η-cyclopentadieny)-cobalt and -rhodium

1974 ◽  
Vol 27 (1) ◽  
pp. 61 ◽  
Author(s):  
RS Dickson ◽  
HP Kirsch
Keyword(s):  
Transition Metal ◽  
Metal Complexes ◽  
Transition Metal Complexes ◽  
Major Product ◽  
Reaction Conditions ◽  
A Minor ◽  
Related Reaction

The thermally initiated reaction of hexafluorobut-2-yne and (q-C5H5)C~(C0)2 gives the 1-4-q- hexakis(trifiuoromethy1)benzene complex (7-C5H5)Co [(CF3C2CF3)3] in addition to the known cyclopentadienone complex (q-C5H5)Co [(CF3C2CF3)2CO]. The related reaction of but-2-yne with (q-CjH j)Co(CO)2 gives several compounds in addition to the cyclopentadienone complex (q-C jHj)C~- [(MeC2Me)2CO] which has been isolated previously from this reaction. Thus, the duroquinone complex (q-C5H5)Co [(MeC2Me)2(C0)2], the maleoyl complex (q-C5H5)Co(MeC2Me)(C0)3, and free duroquinone have been obtained. The yields of the various products are influenced by the reaction conditions. The metallocyclopentadiene complex (q-C jH j)2Rh2(CF3C2CF3)2, which is formed in the reaction between (q-C,H,)Rh(CO), and hexafluorobut-2-yne, exhibits fluxional behaviour in solution at c. 130". Two complexes are formed in the reaction at 100-120' between (q-C5Hj)Rh- (CO)2 and but-2-yne. These are the cyclopentadienone complex (q-C5H5)Rh [(MeC2Me)2CO] and the duroquinone complex (7-CjH5)Rh [(MeC2Me)2(C0)2]. Comparison of the various reactions indicates that: (i) a cyclopentadienone complex (q-CgH5)M- [(MeC2Me)2CO] is generally formed as major product and a duroquinone complex (q-C5Hj)M- [(MeC2Me)2(C0)2] is generally formed as a minor product in reactions between (q-C5H5)M(C0)2, M = Co and Rh, and but-2-yne; and (ii) a tetrahaptobenzene complex (q-C5H5)M [(CF3C2CF3)3] is formed as major product when M = Rh and as a minor product when M = Co in reactions between (q-C5H5)M(CO)2 and hexafluorobut-2-yne.

scholarly journals A new tetracyclic diterpenoid from the seeds of Euphorbia lathyris

2020 ◽  
Vol 44 (5-6) ◽  
pp. 322-325
Author(s):  
Lie-Feng Ma ◽  
Yue Zhang ◽  
Xuan Zhang ◽  
Meng-Jia Chen ◽  
Zha-Jun Zhan ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Nuclear Magnetic Resonance ◽  
High Resolution ◽  
Spectroscopic Data ◽  
Resonance Spectroscopy ◽  
Ionization Mass ◽  
Two Dimensional ◽  
Detailed Interpretation ◽  
A Minor ◽  
Euphorbia Lathyris

Eupholathone, a minor diterpenoid with an unusual tetracyclic skeleton, was obtained from the seeds of Euphorbia lathyris, along with two known lathyrane diterpenoids, euphorbia factors L2 and L3. The structure of eupholathone was elucidated by detailed interpretation of its spectroscopic data, especially two-dimensional nuclear magnetic resonance spectroscopy and high-resolution electrospray ionization mass spectrometry.

Decomposition of Ethoxyethynyl(trimethyl)tin - Studied by 119Sn and 13C NMR Spectroscopy

1999 ◽  
Vol 54 (6) ◽  
pp. 705-708 ◽  
Author(s):  
Bemd Wrackmeyer ◽  
Sergei V. Ponomarev
Keyword(s):  
Chemical Shifts ◽  
Acid Ethyl Ester ◽  
13C Nmr Spectroscopy ◽  
Major Product ◽  
Coupling Constants ◽  
Data Sets ◽  
Thermally Induced ◽  
Nmr Data ◽  
Induced Decomposition ◽  
A Minor

The thermally induced decomposition of ethoxyethynyl(trimethyl)tin (1) was studied by 119Sn NMR which revealed the formation o f bis(trimethylstannyl) ketene (2) as the major product, bis(trimethylstannyl) acetic acid ethyl ester (3) as a minor product, and a small amount o f tetramethyltin (4). Full NMR data sets, including coupling constants and isotope induced chemical shifts 1Δ12/ 13C(119Sn) are provided for 1-3 . The first example o f ultra-high resolution 119Sn NMR is shown

Photo-additions of Naphthalene Derivatives with Substituted Ethylenes: Influence of Methoxy- and Cyano-substituents on the Products

1973 ◽  
Vol 51 (15) ◽  
pp. 2578-2589 ◽  
Author(s):  
Terence Richard Chamberlain ◽  
John James McCullough
Keyword(s):  
Vinyl Ether ◽  
Spectroscopic Data ◽  
Methoxy Group ◽  
Major Product ◽  
Naphthalene Derivatives ◽  
Methyl Vinyl ◽  
Nuclear Overhauser ◽  
Nuclear Overhauser Effects ◽  
Methyl Vinyl Ether

Irradiation of 2-methoxynaphthalene and acrylonitrile in ethanol affords exo- and endo-7-cyano-6-methoxy-2,3-benzobicyclo[4.2.0]octa-2,4-diene, in the ratio 30:70. The structures are assigned from the n.m.r. spectra. The endo compound is the more stable, and on base equilibration predominates (90%). These adducts eliminate a methoxy-group on treatment with tert-butoxide at 80°, to afford 2,3-naphtho-cyclobutene carboxamide. Irradiation of 2-cyanonaphthalene and methyl vinyl ether in ethanol gives a complicated mixture of adducts which includes the cyclobutane 7-methoxy-6-cyano-2,3-benzobicyclo-[4.2.0]octa-2,4-diene as a major product (35%). Also formed are 7-methoxy-2,3(8-cyanobenzo)bicyclo-[3.3.0]octa-2,7-diene (8%), 8-methoxy-10-cyano-1,2-benzocycloocta-1,3,5-triene (18%), and a dimer of the latter (7%), and 8-methylene-5-methoxy-2,3(10-cyanobenzo)bicyclo[2.2.1]heptene (35%). The structures of the latter adducts are assigned from spectroscopic data, including nuclear Overhauser effects. Possible mechanisms for formation of the latter adducts, and a rule for prediction of regiospecificity in cyclobutane formation, are proposed.

Photo-additions of aromatic hydrocarbons—indene and naphthalene with acrylonitrile

1969 ◽  
Vol 47 (5) ◽  
pp. 757-766 ◽  
Author(s):  
John J. McCullough ◽  
C. W. Huang
Keyword(s):  
Butyl Alcohol ◽  
Major Product ◽  
Minor Amount ◽  
Strong Base ◽  
Magnetic Resonance Data ◽  
Cis And Trans Isomers ◽  
Resonance Data ◽  
Ethanol Yields ◽  
A Minor ◽  
Cis And Trans

The photolyses of indene and naphthalene with acrylonitrile have been studied, and the products characterized. Indene reacts with acrylonitrile when the hydrocarbon absorbs light, or when a triplet sensitizer (acetophenone) is absorbing. Photolysis under the former conditions in ethanol yields 2-(1-indenylpropionitrile) (70%), 2-(3-indenylpropionitrile) (10%), and 6-cyano-2,3-benzobicyclo[3,2,0]hept-2-ene (20%). Base-catalyzed isomerizations of the substituted indenes are reported. On sensitization, cis- and trans-isomers of 7-cyano-2,3-benzobicyclo[3,2,0]hept-2-ene are formed, with a minor amount of indene dimer. The former isomers can be equilibrated with strong base. Adducts of 1,1-dimethyl- and 1,1-diphenylindene with acrylonitrile are also described, and nuclear magnetic resonance data reported. Naphthalene adds acrylonitrile on photolysis in t-butyl alcohol (pyrex filter) to afford trans-8-cyano-2,3-benzobicyclo-[4,2,0]-octa-2,4-diene (90%) and 1- and 2-naphthyl-2-propionitrile (10%). Sensitization with acetophenone gave no detectable products. Irradiation of the major product at 253.7 mμ through Vycor gave naphthalene. The preparative value of these reactions is considered and possible mechanisms are proposed.

Synthesis of some bicyclo[2.2.2]oct-5-en-2-ones and bicyclo[2.2.2]octan-2-ones. Rearrangements accompanying oxidative decarboxylation with lead tetraacetate

1981 ◽  
Vol 59 (2) ◽  
pp. 344-355 ◽  
Author(s):  
Peter Yates ◽  
Gordon E. Langford
Keyword(s):  
Dicarboxylic Acid ◽  
Acyl Migration ◽  
Dicarboxylic Acids ◽  
Acid Group ◽  
Major Product ◽  
Lead Tetraacetate ◽  
Oxidative Decarboxylation ◽  
Similar Treatment ◽  
Carbonium Ion ◽  
A Minor

1-Methoxy-2-methyl-1,4-cyclohexadiene (3), 2-methoxy-1-methyl-1,3-cyclohexadiene (2), and 2-methoxy-1,5,5-trimethyl-1,3-cyclohexadiene (14) on heating with maleic anhydride give 1-methoxy-endo-7-methylbicyclo[2.2.2]oct-5-ene-syn-2,3-dicarboxylic acid anhydride (7) and its 6-methoxy-1-methyl (16a) and 6-methoxy-1,8,8-trimethyl (16b) analogues, respectively. On hydrolysis 16a and 16b give the corresponding keto dicarboxylic acids, 18a and 18b, via keto anhydrides 17a and 17b. Treatment of 18b with lead tetraacetate gives 1,8,8-trimethylbicyclo[2.2.2]oct-5-en-2-one (19) together with products in which rearrangement to a bicyclo[3.2.1]octane system has occurred. Treatment of 17b with bis(triphenylphosphino)nickel dicarbonyl gives only 19; similar treatment of 17a gives 1-methylbicyclo[2.2.2]oct-5-en-2-one (1). Reaction of bicyclo[2.2.2]octane-2,3-dione (27) with methyllithium gives 3-hydroxy-3-methylbicyclo[2.2.2]octan-2-one (28), its dimer 31, and a diol 30. Treatment of 5-exo-acetoxy-1, 5-endo-dimethyl-6-oxobicyclo[2.2.2]octane-anti-2,3-dicarboxylic acid (37) with lead tetraacetate gives 3-endo-acetoxy-1,3-exo-dimethyl-bicyclo[2.2.2]oct-5-en-2-one (33) as a minor product; the major product is derived by rearrangement to a bicyclo[3.2.1]octane system. It is proposed that this rearrangement, like that of 18b, involves oxidative decarboxylation of a single carboxylic acid group to give a carbonium ion that undergoes rearrangement via a 1,2-acyl migration.

Tyrosinase Inhibitory Activity of Pyrazole Derivatives

2012 ◽  
Vol 506 ◽  
pp. 194-197
Author(s):  
T. Suwunwong ◽  
T. Kobkeatthawin ◽  
K. Chanawanno ◽  
N. Saewan ◽  
P. Wisitsak ◽  
...  
Keyword(s):  
Inhibitory Activity ◽  
Spectroscopic Data ◽  
Kojic Acid ◽  
Data Interpretation ◽  
Pyrazole Derivatives ◽  
Tyrosinase Inhibitory Activity

A series of 3,5-substituted-4,5-dihydro-1H-pyrazole-1-carbothioamide derivatives were synthesized. Their structures were determined on the basis of spectroscopic data interpretation and their tyrosinase inhibitory activity was determined. The results showed that compound 2 (at 1.00 mg/mL) exhibits significant tyrosinase inhibitory activity with % inhibition of 91.866 ± 2.086 with L-tyrosine as substrate whereas compound 3 (at 1.00 mg/mL) exhibits significant tyrosinase inhibitory activity with % inhibition of 79.266 ± 0.552 and 89.593 ± 1.015 with L-tyrosine and L-DOPA as substrates. The IC50values of compounds 2 and 3 were further determined comparing with kojic acid and resveratrol. It was found that IC50values of compounds 2 and 3 were 0.391 ± 0.017 and 0.259 ± 0.005 mg/mL., with L-tyrosine as substrate, which were lower than those of the standard tyrosinase inhibitory resveratrol (0.965 ± 0.016 mg/mL).

scholarly journals Lampiran 1F Paper Single production of Kojic acid by Aspergillus flavus and the revision of flufuran

2021 ◽  
Author(s):  
Philiphi de Rozari
Keyword(s):  
Aspergillus Flavus ◽  
Endophytic Fungi ◽  
Catharanthus Roseus ◽  
Spectroscopic Data ◽  
Kojic Acid ◽  
Annona Squamosa ◽  
Nmr Data ◽  
Toxic Metabolites ◽  
Single Production ◽  
Industrial Use

Timor Island is very hot and dry due to the high intensity of sunlight experienced throughout the year. The endophytic fungi Aspergillus flavus had been isolated from medicinal plants such as Catharanthus roseus, Annona squamosa and Curcuma xanthorisa. The endophytic fungi A. flavus from each plant was cultivated on solid rice media and then analyzed for its capability for producing kojic acid. The production of kojic acid was analyzed by HPLC; the highest amount of kojic acid was observed from the endophytic fungi A. flavus, isolated from the stem of Catharanthus roseus, followed by A. flavus from Annona squamosa and Curcuma xanthorisa. Simple VLC fractionation of the extract of A. flavus from C.roseus led to the isolation of around 11.1 g of pure kojic acid. The structure of kojic acid (1) was confirmed by NMR and MS spectroscopic data. A comparison of the NMR data with the literature supported the revision of the natural product flufuran to kojic acid. To the best of our knowledge, this is the first report of a strain of endophytic fungi producing only kojic acid without any other toxic metabolites such as alfatoxins. Therefore, this Aspergillus flavus strain can be applied as a potential producer of kojic acid for industrial use.

Sign in / Sign up

Export Citation Format

Share Document