Roberto Ballini 1,*, Marino Petrini 1 and Goffredo Rosini 2
1 Dipartimento di Scienze Chimiche, Università di Camerino, via S.Agostino, 1, I-62032 Camerino, Italy; E-mail: [email protected]
2 Dipartimento di Chimica Organica ‘A. Mangini’, Alma Mater Studiorum–Università di Bologna, Viale del Risorgimento n. 4, 40136 Bologna, Italy; E-mail: [email protected]
* Author to whom correspondence should be addressed; E-mail: [email protected]; Fax: +39 0737 402297
Received: 8 January 2008; in revised form: 2 February 2008 / Accepted: 4 February 2008 / Published: 7 February 2008
Review: Nitroalkanes as Central Reagents in the Synthesis of Spiroketals
Molecules 2008, 13, 319-330 (PDF format 81 K)
Giuseppe A. Consiglio, Salvatore Failla and Paolo Finocchiaro*
Dipartimento di Metodologie Fisiche e Chimiche per l`Ingegneria, Università di Catania, Viale A. Doria, 6-95125-Catania Italy; E-mails: [email protected] (Giuseppe A. Consiglio);
[email protected] (Salvatore Failla); [email protected] (Paolo Finocchiaro)
* Author to whom correspondence should be addressed; E-mail: [email protected]
Received: 25 February 2008; in revised form: 14 March 2008 / Accepted: 16 March 2008 / Published: 20 March 2008
Review: New Cleft-like Molecules and Macrocycles from Phosphonate Substituted Spirobisindanol
Molecules 2008, 13, 678-700 (PDF format 190 K)
M. Isabel García-Moreno 1,*, Juan M. Benito 2,*, Carmen Ortiz Mellet 1 and José M. García Fernández 2
1 Departamento de Química Orgánica, Facultad de Química, Universidad de Sevilla, Profesor García González 1, 41012 Sevilla, Spain; E-mail: [email protected]
2 Instituto de Investigaciones Químicas, CSIC – Universidad de Sevilla, Américo Vespucio 49, Isla de la Cartuja, 41092 Sevilla, Spain; E-mail: [email protected]
* Author to whom correspondence should be addressed: E-mail: [email protected], [email protected].
Received: 20 June 2008; in revised form 22 July 2008 / Accepted: 28 July 2008 / Published: 12 August 2008
Review: Chemical and Enzymatic Approaches to Carbohydrate-Derived Spiroketals: Di-D-Fructose Dianhydrides (DFAs)
Molecules 2008, 13, 1640-1670 (PDF format 508 K); DOI: 10.3390/molecules13081640
B. Rama Raju and Anil K. Saikia *
Department of Chemistry, Indian Institute of Technology Guwahati, Guwahati 781039, India
E-mail: [email protected]
* Author to whom correspondence should be addressed; E-mail: [email protected].
Received: 21 July 2008; in revised form: 22 August 2008 / Accepted: 22 August 2008 / Published: 28 August 2008
Review: Asymmetric Synthesis of Naturally Occuring Spiroketals
Molecules 2008, 13, 1942-2038 (PDF format 814 K); DOI: 10.3390/molecules13081942
Mounir Maafi
Leicester School of Pharmacy, De Montfort University, The Gateway, Leicester, LE1 9BH, UK.
E-mail: [email protected]. Tel: +44 116 257 7704; Fax: +44 116 257 7287
Received: 14 August 2008; in revised form: 19 September 2008 / Accepted: 19 September 2008 / Published: 25 September 2008
Review: Useful Spectrokinetic Methods for the Investigation of Photochromic and Thermo-Photochromic Spiropyrans
Molecules 2008, 13, 2260-2302 (PDF format 487 K); 10.3390/molecules13092260
Molecules Manuscript ID: spirocompounds-20071214-Gerber-ch
Type of the paper: Review
Title: Synthetic Approaches toward the Spiroketals Subunits of Spongistatins
Authors: Sandrine Gerber * and Sylvain Favre
ISIC-Direction, Ecole Polytechnique Fédérale de Lausanne, EPFL SB ISIC, Station 6
CH-1015 Lausanne, Switzerland
Laboratoire de Glycochimie et Synthèse Asymétrique
Tel : +41 21 693 93 72, Fax: +41 21 693 93 55; E-mail: [email protected]
http://isic2.epfl.ch/page59148.htlm
Abstract: Spiroketals and in particular 6,6-congeners are key structural features of a variety of natural products of biological interest. In particular, spongistatins (altohyrtins), which have been isolated in 1993 by three research groups from marine sponges of the genus Spongia, present two highly functionalized 6,6-spiroketal subunits in their skeleton. These molecules were found to be among the most potent cancer cells growth inhibitors tested to date by the U.S. National Cancer Institute on a panel of 60 human carcinoma cell lines, with GI50 values in the nanomolar and picomolar ranges. Despite these promising properties, further biological investigations were precluded by the extremely low quantities that can be obtained by extraction of marine organisms and the unacceptable ecological impact of larger scale isolation of the producing sponges. This scarce abundance, combined with remarkable structural complexity, prompted many research groups to address the challenge of the synthesis of these macrolides. Several total syntheses have been reported and many routes to key subunits have also been described. In particular, considerable efforts have been devoted to the efficient preparation of the axial / axial AB and axial / equatorial CD spiroketals and on the EF tetrahydropyran fragment. In this review we shall concentrate on the various approches that have been reported toward the efficient delivery of the spiroketals fragments of spongistatins and on their assembly. The biological activity of these macrolides will also be discussed.
Molecules Manuscript ID: spirocompounds-20080209-Guirado-es
Type of the paper: Review
Title: Stable Spirocyclical Meisenheimer Complexes
Authors: Rabih O. Al-Kaysi 1,*, Iluminada Gallardo2 and Gonzalo Guirado2,*
1 King Saud Bin Abdulaziz University for Health Sciences. National Guard-Health Affairs.
Mail Building Code 1150. Riyadh 11423. Kingdom of Saudi Arabia. Phone: (966)-5-61429528 ; Email: [email protected]
2Departament de Química, Universitat Autònoma de Barcelona, 08193-Bellaterra, Barcelona, Spain; Phone: (+ ) 00 34 93 581 48 82; Fax: (+) 00 34 93 581 29 20
E-mail: [email protected] ; [email protected]
* Author to whom correspondence should be addressed. (Apply M_address)
Abstract: Meiseheimer complexes are important intermediates in Nucleophilic Aromatic Substitution Reaction (SNAr) formed by the addition of electron rich species to polynitoraromatic compounds or aromatic compounds with strong electron withdrawing groups. It is possible to distinguish two types of Meisenheimer or σ-complexes, the σH-complex or σX-complex (also named ipso), depending on the aromatic ring position attacked by the nucleophile (a non-substituted or substituted one, respectively). A special case of σX- or ipso-complexes are formed through intermediate spiro adducts, via intramolecular SNAr. Some of these spirocyclical Meisenheimer or sX-complexes are exceptionally stable in solution and/or as solids. They can be isolated and characterized using X-ray, and various spectroscopical techniques such as NMR, UV-vis, IR, and fluorescence. However, only a few of these stable spirocyclical Meisenheimer complexes are zwitterionic and exhibit interesting photophysical and redox properties. This manuscript will review recent advances, scope and potential applications of these stable spirocyclical Meisenheimer complexes.
