Reaction of P,P,P-trihalogenbenzo-1,3,2-dioxaphospholes with terminal acetylenes: Phosphorus-carbon bond formation and the ipso-substitution of oxygen by carbon
07 Mar 2011-Vol. 1, Iss: 1, pp 27-55
TL;DR: In this article, a new reaction in phosphorus chemistry, namely, the interaction of 2,2,2-trihalobenzo-1, 3, 2-dioxaphospholes with aryl(alkyl)acetylenes, leads to the formation of benzo[e]-1,2oxaphosphinine derivatives, or “phosphacoumarins.
Abstract: The account covers a new reaction in phosphorus chemistry, namely, the interaction of 2,2,2-trihalobenzo-1,3,2-dioxaphospholes with aryl(alkyl)acetylenes, which leads to the formation of benzo[e]-1,2-oxaphosphinine derivatives, or “phosphacoumarins.” The easy formation of a P-C bond and phosphoryl group, the ipso-substitution of the oxygen atom by the carbon one, and selective chlorination para to endocyclic oxygen are realized under mild conditions in this reaction. The ipso-substitution of a tertiary butyl group and a bromine atom also takes place in some cases.
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TL;DR: A new class of aromatic metamorphosis in which benzofurans are converted into diverse six-membered oxaheterocycles has been developed and is composed of two reactions in one pot: manganese-catalyzed arylative or alkylative ring-opening of benz ofurans affording dianionic intermediates and subsequent trapping with multivalent heteroatom electrophiles.
31 citations
TL;DR: In this paper, an intramolecular hydroarylation of aryl alkynylphosphonates (I) and (III) promoted by a gold/silver catalyst affords phosphacoumarins (II and (IV) in moderate to good yields via a 6-endo-dig cyclization.
Abstract: An intramolecular hydroarylation of aryl alkynylphosphonates (I) and (III) promoted by a gold/silver catalyst affords phosphacoumarins (II) and (IV), resp., in moderate to good yields via a 6-endo-dig cyclization.
29 citations
TL;DR: This review emphasizes on the synthetic methods for the preparation of dialkyl 2-oxo-2H-1-benzo- pyran- 3-phosphonates and alkyl 1,2-benzoxaphosphorin-3-carboxylates.
Abstract: Coumarins are an important class of natural heterocyclic compounds that have attracted considerable synthetic and pharmacological interest due to their various biological activities. This review emphasizes on the synthetic methods for the preparation of dialkyl 2-oxo-2H-1-benzo- pyran-3-phosphonates and alkyl 1,2-benzoxaphosphorin-3-carboxylates. Their chemical properties as acceptors in conjugate addition reactions, [2+2] and [3+2] cycloaddition reactions are discussed.
12 citations
TL;DR: In this article, 8,8'-Spirobi(chromano-1,2-oxaphosphinines) were obtained by the reaction between phosphorylated derivatives of spirodichromane and arylacetylenes with a high chemoselectivity.
4 citations
TL;DR: Bis(benzo[e]-1,2-oxaphosphinin-2,oxid-4(7)-yl)butane (-benzene) derivatives were synthesized for the first time both on the basis of reactions of diacetylene with P,P, P-trihalobenzo-1,3,2dioxaphopholes.
Abstract: Bis(benzo[e]-1,2-oxaphosphinin-2-oxid-4(7)-yl)butane (-benzene) derivatives were synthesized for the first time both on the basis of reactions of diacetylene with P,P, P-trihalobenzo-1,3,2-dioxaphopholes and on the basis of reactions of bis(P,P,P-trihalobenzo-1,3,2-dioxaphosphol-5-yl)bytane (-benzene) with phenylacetylene.
4 citations
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Book•
30 Sep 1997
TL;DR: In this article, the CHEC III is organized in 15 volumes and closely follows the organization used in the previous edition: Volumes 1 and 2: Cover respectively three and four-membered heterocycles, together with all fused systems containing a three- or four-measured heterocyclic ring.
Abstract: CHEC III is organized in 15 Volumes and closely follows the organization used in the previous edition: Volumes 1 and 2: Cover respectively three- and four-membered heterocycles, together with all fused systems containing a three- or four-membered heterocyclic ring. Volume 3: Five-membered rings with one heteroatom together with their benzo- and other carbocyclic-fused derivatives. Volumes 4, 5 and 6: Cover five-membered rings with two heteroatoms, and three or more heteroatoms, respectively, each with their fused carbocyclic compounds. Volumes 7, 8 and 9: Dedicated to six-membered rings with one, two, and more than two heteroatoms, respectively, again with the corresponding fused carbocylic compounds. Volumes 10, 11 and 12: Cover systems containing at least two directly fused heterocyclic five- and/or six-membered rings: of these Volume 10 deals with bi-heterocyclic rings without a ring junction heteroatom, and Volume 11 deals with 5:5 and 5:6 fused rings systems with at least one ring junction nitrogen, while Volume 12 is devoted to all other systems of five and/or six-membered fused or spiro heterocyclic rings with ring junction heteroatoms. Volumes 13 and 14: Seven-membered and larger heterocyclic rings including all their fused derivatives (except those containing three- or four-membered heterocyclic rings which are included in Volume 1 and 2, respectively). Volume 15: Author, ring and subject indexes.
8,174 citations
Book•
01 Jun 1977
TL;DR: Localized Chemical bonding Delocalized Chemical Bonding Bonding Weaker than Covalent Stereochemistry Carbocations, Carbanions, Free Radicals, Carbenes and Nitrenes Mechanisms and Methods of Determining them Photochemistry Acids and Bases Effects of Structure on Reactivity Aliphatic Nucleophilic Substitution Aromatic Electrophilic Substitutes Aliphatically Electrophilic Substitution Free-Radical Substitution Addition to Carbon-Carbon Multiple Bonds Adding to Carbon Hetero Multiple Bonds Eliminations Rearrangements Ox
Abstract: Localized Chemical bonding Delocalized Chemical Bonding Bonding Weaker than Covalent Stereochemistry Carbocations, Carbanions, Free Radicals, Carbenes and Nitrenes Mechanisms and Methods of Determining Them Photochemistry Acids and Bases Effects of Structure on Reactivity Aliphatic Nucleophilic Substitution Aromatic Electrophilic Substitution Aliphatic Electrophilic Substitution Free-Radical Substitution Addition to Carbon-Carbon Multiple Bonds Addition to Carbon- Hetero Multiple Bonds Eliminations Rearrangements Oxidations and Reductions The Literature of Organic Chemistry Classifications of Reactions by Type of Compound Synthesized.
4,885 citations
1,398 citations
TL;DR: Simple coumarins possessing ortho-dihydroxy functions, such as fraxetin and 4-methyldaphnetin, are potent inhibitors (low micromolar) of lipid peroxidation and scavengers of superoxide anion radicals and of aqueous alkylperoxyl radicals, but may be pro-oxidant (enhancing generation of hydroxyl radicals) in the presence of free iron ions.
Abstract: 1.
1. More than 1300 coumarins have been identified from natural sources, especially green plants. The pharmacological and biochemical properties and therapeutic applications of simple coumarins depend upon the pattern of substitution. More complex related compounds based on the coumarin nucleus include the dicoumarol/warfarin anticoagulants, aflatoxins and the psoralens (photosensitizing agents).
2.
2. Coumarin itself (1,2-benzopyrone) has long-established efficacy in slow-onset long-term reduction of lymphoedema in man, as confirmed in recent double-blind trials against elephantiasis and postmastectomy swelling of the arm. The mechanism of action is uncertain, but may involve macrophage-induced proteolysis of oedema protein. However, coumarin has low absolute bioavailability in man (<5%), due to extensive first-pass hepatic conversion to 7-hydroxycoumarin followed by glucuronida. tion. It may, therefore, be a prodrug.
3.
3. Scoparone (6,7-dimethoxycoumarin) has been purified from the hypolipidaemic Chinese herb Artemisia scoparia and shown to reduce the proliferative responses of human peripheral mononuclear cells, to relax smooth muscle, to reduce total cholesterol and triglycerides and to retard the characteristic pathomorphological changes in hypercholesterolaemic diabetic rabbits. Various properties of scoparone were suggested to account for these findings, including ability to scavenge reactive oxygen species, inhibition of tyrosine kinases and potentiation of prostaglandin generation.
4.
4. Osthole (7-methoxy-8-[3-methylpent-2-enyl]coumarin) from Angelica pubescens, used also in Chinese medicine, causes hypotension in vivo, and inhibits platelet aggregation and smooth muscle contraction in vitro. It may interfere with calcium influx and with cyclic nucleotide phosphodiesterases.
5.
5. Cloricromene, a synthetic coumarin derivative, also possesses antithrombotic antiplatelet actions, inhibits PMN neutrophil function and causes vasodilatation. Some of these properties of cloricromene have been ascribed to inhibition of arachidonate release from membrane phospholipids.
6.
6. Simple coumarins possessing ortho-dihydroxy functions, such as fraxetin and 4-methyldaphnetin, are potent inhibitors (low micromolar) of lipid peroxidation and scavengers of superoxide anion radicals and of aqueous alkylperoxyl radicals, but may be pro-oxidant (enhancing generation of hydroxyl radicals) in the presence of free iron ions. These coumarins also inhibit the proinflammatory 5-lipoxygenase enzyme at micromolar concentrations. Another related coumarin, 5, 7-dihydroxy-4-methylcoumarin, is of special interest as it inhibits lipid peroxidation, and scavenges alkylperoxyl and superoxide radicals. Unlike most other simple coumarins studied, 5,7-dihydroxy-4-methylcoumarin also scavenges hypochlorous acid, and is a potent inhibitor of cyclo-oxygenase, but is not pro-oxidant.
7.
7. 5,7- and 6,7-dihydroxy-4-methylcoumarin both reduced the duration of ventricular fibrillation in postischaemic reperfused isolated perfused rat hearts (in which oxygen-derived free radicals are implicated), showing that these antioxidant coumarins possess beneficial properties in this pathophysiological model.
8.
8. In view of the established low toxicity, relative cheapness, presence in the diet and occurrence in various herbal remedies of coumarins, it appears prudent to evaluate their properties and applications further.
874 citations
TL;DR: The present work is to survey the information published or abstracted from 1990 till 2003, which is mainly related to the occurrence, synthesis and biological importance of simple coumarins and some analogues, such as biscou marins and triscoumarins.
Abstract: Coumarins, also known as benzopyrones, are present in remarkable amounts in plants, although their presence has also been detected in microorganisms and animal sources. The structural diversity found in this family of compounds led to the division into different categories, from simple coumarins to many other kinds of policyclic coumarins, such as furocoumarins and pyranocoumarins. Simple coumarins and analogues are a large class of compounds that have attracted their interest for a long time due to their biological activities: they have shown to be useful as antitumoural, anti-HIV agents and as CNS-active compounds. Furthermore, they have been reported to have multiple biological activities (anticoagulant, anti-inflammatory), although all these properties have not been evaluated systematically. In addition, their enzyme inhibition properties, antimicrobial and antioxidant activities are other foremost topics of this field of research. The present work is to survey the information published or abstracted from 1990 till 2003, which is mainly related to the occurrence, synthesis and biological importance of simple coumarins and some analogues, such as biscoumarins and triscoumarins. Data are also highlighted, concerning the development of new synthetic strategies that could help in drug design and in the work on SAR or QSAR.
821 citations