This work was supported by the Foundation for Science and Technology (FCT), Portugal (projects PTDC/QUI-QUI/113687/2009 and PEst-C/QUI/UI0081/2013). A.G. (SFRH/BD/43531/2008) and M.J.M. (SFRH/BD/61262/2009) thank FCT for grants.

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Chromone: A Valid Scaffold in Medicinal Chemistry

Die organisch-chemische Synthese hat stets eine grose Faszination auf den Chemiker ausgeubt, und sie wird auch in Zukunft nichts von ihrer Bedeutung verlieren. Es ist eine Binsenweisheit, das alle Chemiker - und nicht nur die - auf die Synthese chemischer Verbindungen, mit denen sie arbeiten wollen, angewiesen sind. So ist die organisch-chemische Synthese heute mehr denn je die Schnittstelle von Organischer Chemie, Biologie. Biochemie, Medizin, Physik und Materialwissenschaft. Man sollte auch nicht vergessen, das die Grundlage der chemischen Industrie die Synthese ist. Fur den Synthetiker aus Leidenschaft aber ist die Synthese weit mehr als nur Mittel zu dem Zweck, Verbindungen in die Hand zu bekommen; sie ist Ausdruck seiner Kreativitat. Intelligenz und seines handwerklichen Konnens, aber auch seiner Ausdauer.

Sequentielle Transformationen in der Organischen Chemie eine Synthesestrategie mit Zukunft

Over the past fifty years, hundreds of polyyne compounds have been isolated from nature. These often unstable molecules are found in sources as common as garden vegetables and as obscure as bacterial cultures. Naturally occurring polyynes feature a wide range of structural diversity and display an equally broad array of biological properties. Early synthetic efforts relied primarily on Cu-catalyzed, oxidative acetylenic homo- and heterocoupling reactions to assemble the polyyne framework. The past 25 years, however, have witnessed a renaissance in the field of polyyne natural product synthesis: transition-metal-catalyzed alkynylation reactions and asymmetric transformations have combined to substantially expand access to natural polyynes. This Review recounts these synthetic achievements and also highlights both the natural source(s) and biological relevance for many of these compounds.

Synthesis of Naturally Occurring Polyynes

Sizable resources, both financial and human, are invested each year in the development of new pharmaceutical agents. However, despite improved techniques, the new compounds often encounter difficulties in satisfying and overcoming the numerous physicochemical and many pharmacological constraints and hurdles. Oxetanes have been shown to improve key properties when grafted onto molecular scaffolds. Of particular interest are oxetanes that are substituted only in the 3-position, since such units remain achiral and their introduction into a molecular scaffold does not create a new stereocenter. This Minireview gives an overview of the recent advances made in the preparation and use of 3-substituted oxetanes. It also includes a discussion of the site-dependent modifications of various physicochemical and biochemical properties that result from the incorporation of the oxetane unit in molecular architectures.

Oxetanes as Versatile Elements in Drug Discovery and Synthesis

Acyclic stereocontrol via allylic organometallic compounds

An efficient method for the alkynylation of oxiranes using alkynyl boranes

A ring opening reaction of oxetanes with lithium acetylides promoted by boron trifluoride etherate

a highly stereoselective synthesis of carbocyclic compounds by the michael induced intramolecular alkylation a stereocontrol of extracyclic chiral centers

Ichiro Hirao

Papers

An efficient method for the alkynylation of oxiranes using alkynyl boranes

A ring opening reaction of oxetanes with lithium acetylides promoted by boron trifluoride etherate

a highly stereoselective synthesis of carbocyclic compounds by the michael induced intramolecular alkylation a stereocontrol of extracyclic chiral centers

A highly stereoselective Michael reaction of simple ester enolates to α,β-unsaturated esters

The alkynylation reaction of oxetanes