18495-25-5Relevant academic research and scientific papers
Catalytic activation of diazo compounds using electron-rich, defined iron complexes for carbene-transfer reactions
Holzwarth, Michael S.,Alt, Isabel,Plietker, Bernd
supporting information; experimental part, p. 5351 - 5354 (2012/07/14)
Carbene transfer: The electron-rich iron complex Bu4N[Fe(CO) 3(NO)] efficiently catalyzes different carbene-transfer reactions. Various diazo compounds can be used. The high stability of the employed iron complexes is demonstrated by the generation of the diazo reagent in situ and a sequential iron-catalyzed allylic sulfenylation/Doyle-Kirmse reaction. Copyright
Synthesis of carbazoles by gold(I)-catalyzed carbocyclization of 2-(enynyl)indoles
Praveen, Chandrasekaran,Perumal, Paramasivan Thirumalai
scheme or table, p. 521 - 524 (2011/04/17)
A new synthetic protocol for carbazoles through gold(I)-catalyzed intramolecular hydroarylation of (Z)-2-(enynyl)indoles was achieved in good yields. The requisite (Z)-2-(enynyl)indoles were synthesized stereoselectively by trimethylgallium-promoted, Z-selective Wittig olefination of N-alkylindole-2-carboxaldehydes with propargyl ylides. Substrates possessing both alkyl as well as aromatic groups are well tolerated under these reaction conditions. Georg Thieme Verlag Stuttgart.
Iron-catalyzed synthesis of functionalized 2H-chromenes via intramolecular alkyne-carbonyl metathesis
Bera, Krishnendu,Sarkar, Soumen,Biswas, Srijit,Maiti, Sukhendu,Jana, Umasish
experimental part, p. 3539 - 3544 (2011/06/23)
An iron-catalyzed intramolecular alkyne-aldehyde metathesis strategy of the alkynyl ether of salicylaldehyde derivatives has been developed which works under mild reaction conditions to produce the functionalized 2H-chromene derivatives. This protocol is compatible toward a wide range of functional groups, such as methoxy, fluoro, chloro, bromo, and phenyl groups. This method provides an atom-economical and environmentally friendly approach for the synthesis of a series of substituted 2H-chromenes.
Preparation of halo enol phostones by reaction of acetylenic phosphonate monoesters with (bis-collidine)halo hexafluorophosphate
André, Virginie,Robin, Sylvie,Rousseau, Gérard
, p. 5059 - 5062 (2008/12/20)
Reaction of non-conjugated acetylenic phosphonate monoesters with (bis-collidine) bromo and iodo hexafluorophosphates was found to lead to the formation of halo enol phostones. Depending on the size of the heterocyclic compounds formed (6-8-membered compo
Palladium(II)-catalyzed enyne coupling reaction initiated by acetoxypalladation of alkynes and quenched by protonolysis of the carbon-palladium bond
Zhao, Ligang,Lu, Xiyan,Xu, Wei
, p. 4059 - 4063 (2007/10/03)
Divalent palladium-catalyzed inter- and intramolecular enyne coupling reactions initiated by acetoxypalladation of alkynes were developed. The reaction involves the acetoxypalladation of the alkyne, followed by the insertion of the alkene and the protonolysis of the carbon-palladium bond. The protonolysis of the carbon-palladium bond in the presence of bidentate nitrogen containing ligands is the key step in completing the Pd(II) catalytic cycle. The nitrogen-containing ligands, like halides, served to favor the protonolysis of the carbon-palladium bond over the β-H elimination in the Pd(II)-mediated reactions. The intermolecular coupling reactions provide an efficient method for synthesizing γ,δ-unsaturated carbonyls. The intramolecular coupling reactions offer a method to construct a variety of synthetically important carbo- and heterocycles. The asymmetric version of such a cyclization was developed with moderate enantioselectivity when employing pymox (pyridyl monooxazoline) as the ligand.
(Chloro-phenylthio-methylene)dimethylammonium chloride (CPMA) an efficient reagent for selective chlorination and bromination of primary alcohols
Gomez,Gellibert,Wagner,Mioskowski
, p. 6049 - 6052 (2007/10/03)
(Chloro-phenylthio-methylene)dimethylammonium chloride reacts smoothly with a variety of alcohols, to afford the corresponding alkyl chloride in good yields. In the presence of tetrabuthylammonium bromide the corresponding bromide is obtained. Selective halogenation of primary hydroxyl groups in the presence of an unprotected secondary one is described. The mild reaction conditions involved are compatible with the major alcohol protecting groups as well as with acid sensitive functions like epoxides. (C) 2000 Elsevier Science Ltd.
Regio- and diastereoselective allenylation of aldehydes in aqueous media: Total synthesis of (+)-goniofufurone
Yi, Xiang-Hui,Meng, Yue,Hua, Xiao-Gang,Li, Chao-Jun
, p. 7472 - 7480 (2007/10/03)
The regio- and diastereoselectivities of metal-mediated allenylation of carbonyl compounds were investigated in aqueous media. Different metal mediators showed varied regioselectivities on product formation during propargylation-allenylation reactions of carbonyl compounds with simple propargyl bromide. Under the standard reaction conditions, the use of indium provided the highest regioselectivity, with a preference of formation of the homopropargyl alcohol. The use of tin and bismuth as the metal mediator provided slightly lower selectivities with the same preference. The use of zinc and cadmium as the mediators further lowered the product selectivity. The reactions of an alipathic aldehyde with simple propargyl bromide showed a lower selectivity than the reaction of an aromatic aldehyde in most cases, except for the use of tin or zinc (where comparable selectivities were observed). On the other hand, the reaction of terminal-substituted propargyl bromides with aldehydes mediated by indium showed a high regioselectivity in forming allenylation products. The indium-mediated allenylation of carbonyl compounds bearing an α-hydroxyl group also proceeded with a high diastereoselectivity, forming syn-diols predominantly in aqueous ethanol. The high diastereoselectivity in allenylation of α-hydroxyl-substituted aldehydes was attributed to the chelation effect exhibited by the α-hydroxyl substituent. Through the use of this highly diastereoselective allenylation, (+)-goniofufurone was synthesized from D'-glucurono-6,3-lactone.
Covalent modification of cyclooxygenase-2 (COX-2) by 2-acetoxyphenyl alkyl sulfides, a new class of selective COX-2 inactivators
Kalgutkar, Amit S.,Kozak, Kevin R.,Crews, Brenda C.,Hochgesang Jr., G. Phillip,Marnett, Lawrence J.
, p. 4800 - 4818 (2007/10/03)
All of the selective COX-2 inhibitors described to date inhibit the isoform by binding tightly but noncovalently at the substrate binding site. Recently, we reported the first account of selective covalent modification of COX-2 by a novel inactivator, 2-acetoxyphenyl hept-2-ynyl sulfide (70) (Science 1998, 280, 1268-1270). Compound 70 selectively inactivates COX-2 by acetylating the same serine residue that aspirin acetylates. This paper describes the extensive structure-activity relationship (SAR) studies on the initial lead compound 2-acetoxyphenyl methyl sulfide (36) that led to the discovery of 70. Extension of the S-alkyl chain in 36 with higher alkyl homologues led to significant increases in inhibitory potency. The heptyl chain in 2-acetoxyphenyl heptyl sulfide (46) was optimum for COX-2 inhibitory potency, and introduction of a triple bond in the heptyl chain (compound 70) led to further increments in potency and selectivity. The alkynyl analogues were more potent and selective COX-2 inhibitors than the corresponding alkyl homologues. Sulfides were more potent and selective COX-2 inhibitors than the corresponding sulfoxides or sulfones or other heteroatom-containing compounds. In addition to inhibiting purified COX-2, 36, 46, and 70 also inhibited COX-2 activity in murine macrophages. Analogue 36 which displayed moderate potency and selectivity against purified human COX-2 was a potent inhibitor of COX-2 activity in the mouse macrophages. Tryptic digestion and peptide mapping of COX-2 reacted with [1-14C-acetyl]-36 indicated that selective COX-2 inhibition by 36 also resulted in the acetylation of Ser516. That COX-2 inhibition by aspirin resulted from the acetylation of Ser516 was confirmed by tryptic digestion and peptide mapping of COX-2 labeled with [1- 14C-acetyl]salicyclic acid. The efficacy of the sulfides in inhibiting COX- 2 activity in inflammatory cells, our recent results on the selectivity of 70 in attenuating growth of COX-2-expressing colon cancer cells, and its selectivity for inhibition of COX-2 over COX-1 in vivo indicate that this novel class of covalent modifiers may serve as potential therapeutic agents in inflammatory and proliferative disorders.
2,5,6,7-tetranor-18,18,19,19-tetradehydro-4,8-inter-m-phenylene PGI2 derivatives
-
, (2008/06/13)
Disclosed herein are novel prostaglandin I2 (PGI2) derivatives exhibiting excellent physiological activities, said derivatives being represented by the general formula: STR1 wherein R1, R2 and R3 are as defined herein.
PHOTOSENSITISED OXIDATION OF MODEL UNSATURATED LIPID SYSTEMS: (4Z,7Z)-UNDECA-4,7-DIENE AND (4Z)-UNDEC-4-EN-7-YNE
Carless, Howard A. J.,Batten, Richard J.
, p. 1999 - 2008 (2007/10/02)
Photosensitised oxidation of the skipped diene (4Z,7Z)-undeca-4,7-diene (4) gave non-conjugated and conjugated dienyl hydroperoxides (5a) and (5b) in the ratio 2:3.Free radical cyclisation of (5a) yielded two stereoisomeric dioxolanyl hydroperoxides (9) and (10). (4Z)- undec-4-en-7-yne (3) led, on photosensitised oxidation ,to non-conjugated and conjugated enynyl hydroperoxides (15) and (14) in the ratio 1:2.Undeca-4,7-diyne (2) proved comparatively resistant to photosensitised oxidation, with the relative rates of attack on (4):(3):(2) being 110:15/=1.There was no evidence for the abstraction of the prop-2-ynyl hydrogen by singlet oxygen in these reactions.
