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ABSTRACT: Heterocyclic enols are used for the first time as acid components in an Ugi-type multicomponent condensation. For that purpose, we have chosen enols containing a Michael acceptor, in order to facilitate an irreversible rearrangement of the primary Ugi adduct. The new four-component process leads readily and efficiently to heterocyclic enamines containing at least six elements of diversity.
Organic Letters 11/2012; · 5.86 Impact Factor
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ABSTRACT: We report a novel Lewis acid catalysed tandem reaction of isocyanides, chromone 3-carboxylic acid and nucleophiles. An experimentally very simple procedure, involving the use of microwave irradiation in the presence of a Lewis acid catalyst, affords a representative collection of chromone-2-carboxamides and chromone-2-carboxamido-3-esters in high yields, in just a few minutes. Such an unprecedented strategy is formally equivalent to a conjugate addition of isocyanides to Michael acceptors.
Organic & Biomolecular Chemistry 03/2012; 10(17):3406-16. · 3.70 Impact Factor
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ABSTRACT: 2-Aminobenzothiazoles are readily synthesised from anilines, sulfur monochloride and isocyanides. The key step consists of an iodine-catalysed insertion of isocyanides into the S-S bond of hydrolysed Herz salts, with concomitant extrusion of sulfur monoxide.
Organic & Biomolecular Chemistry 07/2011; 9(13):4850-5. · 3.70 Impact Factor
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ABSTRACT: A general synthesis of 1,3-dicarbonylic compounds using multicomponent reactions of isocyanides is described. The process involves a Passerini three-component condensation of glyoxal derivatives, isocyanides and acetic acid, followed by metal mediated reductive or solvolytic removal of the acid component. Noteworthy, reductive deacetoxylation of Passerini glyoxylamide adducts was successfully achieved using photochemically activated SmI(2). This procedure constitutes a novel convenient method for the direct synthesis of malonic retro-peptidic subunits.
Molecular Diversity 05/2011; 15(2):529-39. · 3.15 Impact Factor
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ABSTRACT: We have developed a useful modification of the classical preparation of phenanthrenes by UV irradiation of stilbenes in the presence of an oxidant. This modification involves the irradiation, in the presence of base, of stilbenes possessing a sulfonyl group linked to the central double bond. We have proved that this protocol can be successfully applied for the synthesis of diverse phenanthrenes and phenanthrenoids.
The Journal of Organic Chemistry 10/2010; 75(20):6764-70. · 4.45 Impact Factor
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ABSTRACT: Push-pull chromophores based on 1-dicyanomethylene-2-chloro-3-aminoindene are readily synthesized. These compounds undergo dramatic colour changes in the presence of metal cations as a result of the interaction of the amino substituent with the analytes. One of these compounds is a selective copper(ii) colorimetric probe in acetonitrile solution, displaying a dramatic colour change upon coordination of the amine group to the metal centre. These compounds are also selective cyanide sensors in acetonitrile solution because of the disruption of the intramolecular charge transfer process as the result of the nucleophilic addition of the anion to the indene moiety.
Organic & Biomolecular Chemistry 02/2010; 8(3):552-8. · 3.70 Impact Factor
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ABSTRACT: Herein we report a novel, diastereoselective, one-pot, two-step, sequential synthesis of highly functionalized natural product-like spiropyrrolidinochromanones. The process consists of an Ugi four-component condensation of 3-formylchromones with amines, isocyanides, and glyoxylic acids followed by a nucleophilic conjugate addition and intramolecular cyclization. The experimental simplicity and tolerance to a wide variety of substituents makes this method suitable for combinatorial synthesis.
The Journal of Organic Chemistry 08/2009; 74(17):6888-90. · 4.45 Impact Factor
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ABSTRACT: A photocyclization of tosylstilbenes in the presence of base is used as a key reaction in the synthesis of the CC-1065 analogue 5.
The Journal of Organic Chemistry 05/2009; 74(8):3203-6. · 4.45 Impact Factor
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Annalen der Chemie und Pharmacie 10/2005; 2005(23):5055 - 5066. · 3.10 Impact Factor
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ABSTRACT: Several new liquid-crystalline indene and pseudoazulene systems are reported. These molecules give rise to either columnar hexagonal mesophases and/or columnar plastic phases. The unique nature of these compounds stems from their non-classical discotic structure. Although the molecules have rigid aromatic cores, they lack terminal tails and instead the polarizable atoms (S, halogens) or polar groups (CN, CO) act as unusual soft parts. On the basis of many structurally related materials, we conclude that for this type of compound molecular stacking in the solid state is a prerequisite for the appearance of a columnar mesophase, although other intermolecular interactions within the layers are also important in establishing liquid-crystalline order. The behavior reported for these mesomorphic molecules opens up new possibilities in the search for related molecular interactions that might be useful for the construction of supramolecular architectures with particular properties.
Chemistry 10/2005; 11(18):5362-76. · 5.93 Impact Factor
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ABSTRACT: Indene and cyclopentene enaminonitriles were reacted with SCl2, iBu3N and NCS to give the first cyclopenta[1,2,6]thiadiazines that showed unusual characteristics, one as a NIR dye and another as a liquid crystal.
Chemical Communications 02/2005; · 6.17 Impact Factor
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ABSTRACT: The irradiation with UV light of a number of 1,2-diaryl-1-tosylstilbenes, in the presence of base, leads to the corresponding phenanthrenes and heterocyclic analogues. These results are consistent with a mechanism involving the base-induced elimination of p-toluenesulfinic acid from an intermediate 9-tosyl-4a,4b-dihydrophenanthrene, formed by photochemical cyclization of the starting 1,2-diaryl-1-tosylstilbenes. [reaction: see text]
Organic Letters 01/2004; 5(26):4939-41. · 5.86 Impact Factor
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Tetrahedron Letters 46(46):7977-7979. · 2.68 Impact Factor
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ABSTRACT: The Passerini reaction between glyoxals, isocyanides and acetic acid forms β-keto acyloxyamides, which are readily transformed in β-keto amides by reductive deacetoxylation with zinc. The versatility of this procedure, which allows introducing different groups both in position-3 and the amide nitrogen, makes it ideal for its use in diversity-oriented synthesis, in combination with subsequent complexity generation reactions.Graphical abstract
Tetrahedron Letters 46(1):23-26. · 2.68 Impact Factor
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Tetrahedron Letters 49(13):2099-2102. · 2.68 Impact Factor
