Synthesis of E- and Z-substituted methylene-3,4-dihydro-2H-1-benzopyrans by regio- and stereocontrolled palladium-catalyzed intramolecular cyclization
TL;DR: In this paper, a stereocontrolled synthetic approach to E and Z -substituted methylene-3,4-dihydro-2 H -1-benzopyrans is described from acyclic derivatives using as a key step the palladium-catalyzed intramolecular cyclic carbopalladation of iodoalkynes.
About: This article is published in Tetrahedron Letters.The article was published on 2001-04-02. It has received 12 citations till now. The article focuses on the topics: Benzopyrans & Intramolecular force.
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TL;DR: Carbonickelations of alkynes and functionalization of the resulting vinylnickel moiety have been performed efficiently in a nickel-catalyzed domino cyclization-condensation process and are shown to be useful synthons for rapid access to functionalized polycyclic skeletons.
Abstract: Carbonickelations of alkynes and functionalization of the resulting vinylnickel moiety have been performed efficiently in a nickel-catalyzed domino cyclization-condensation process. This reaction, which does not require the preparation of any other organometallic reagent, proceeds only by exo-dig cyclization. This convenient and mild method constitutes a one-pot synthesis of substituted dihydrobenzofurans, chromans, isochromans, indoles, or indanes. Theses valuable products are generally obtained in good yields and high stereoselectivity. They are shown to be useful synthons for rapid access to functionalized polycyclic skeletons.
38 citations
TL;DR: Reaction of Ni(0) in the presence of iodoarylethers leads, after syn intramolecular carbonickelation of the triple bond, to nucleophilic vinylnickels which can be trapped by various electrophiles introduced at the onset of the reaction.
34 citations
01 Jan 2008
31 citations
References
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TL;DR: It is reported that 2-methoxyoestradiol, an endogenous oestrogen metabolite of previously unknown function, is a potent inhibitor of endothelial cell proliferation and migration as well as angiogenesis in vitro.
Abstract: The formation of new blood vessels (angiogenesis) is critical for the growth of tumours and is a dominant feature in various angiogenic diseases such as diabetic retinopathy, arthritis, haemangiomas and psoriasis. Recognition of the potential therapeutic benefits of controlling pathological angiogenesis has led to a search for angiogenesis inhibitors. Here we report that 2-methoxyoestradiol, an endogenous oestrogen metabolite of previously unknown function, is a potent inhibitor of endothelial cell proliferation and migration as well as angiogenesis in vitro. Moreover, when administered orally in mice, it strongly inhibits the neovascularization of solid tumors and suppresses their growth. Unlike the angiostatic steroids of corticoid structure, it does not require the co-administration of heparin or sulphated cyclodextrins for activity. Thus, 2-methoxyoestradiol is the first steroid to have high antiangiogenic activity by itself. Our results suggest that this compound may have therapeutic potential in cancer and other angiogenic diseases.
806 citations
TL;DR: The various elements in this model for the binding of steroidal estrogens by the estrogen receptor are consistent with evidence emerging from the crystal structures of related nuclear hormone receptor ligand complexes.
619 citations
TL;DR: In this paper, a new palladium catalysed-anion capture process is proposed, which involves cyclisation of o-(ω-acetylenic)-aryl iodides and 2-bromo-1,6-enynes to heterocyclic- and carbocyCLic-vinylpalladium species followed by hydride ion capture.
86 citations
TL;DR: It is demonstrated that a spectrum of alterations in extracellular proteolysis is associated with anti‐angiogenesis, and that anti‐ANGiogenesis and anti‐proteolysis are not necessarily correlated.
Abstract: A tightly controlled increase in extracellular proteolysis, restricted both in time and space, is an important component of the angiogenic process, while anti-proteolysis is effective in inhibiting angiogenesis. By focussing on the plasminogen activator (PA)-plasmin system, the objective of the present studies was to assess whether previously described inhibitors of angiogenesis modify bovine microvascular endothelial cell proteolytic properties. We demonstrate that although synthetic angiostatic steroids (U-24067 and U-42129), heparin, suramin, interferon alpha-2a, and retinoic acid are all inhibitors of in vitro angiogenesis, each of these agents has distinct effects on the plasminogen-dependent proteolytic system. Specifically, angiostatic steroids and interferon alpha-2a reduce urokinase-type PA (u-PA) and PA inhibitor-1 activity, while heparin and retinoic acid increase u-PA activity. Suramin reduces cell-associated u-PA activity and greatly increases PAI-1 production at doses which induce monolayer disruption. These findings demonstrate that a spectrum of alterations in extracellular proteolysis is associated with anti-angiogenesis, and that anti-angiogenesis and anti-proteolysis are not necessarily correlated. A reduction in extracellular proteolysis would be expected to reduce invasion, whereas an increase in proteolysis might modulate the activity of inhibitory cytokines, which in turn could reduce endothelial cell proliferation and migration and inhibit angiogenesis. The spectrum of effects on different elements of the PA system observed in response to the agents assessed suggests that the role of modulations in extracellular proteolytic activity in anti-angiogenesis is likely to be varied and complex.
84 citations