Algirdas Šačkus

1,2-Glycerol Carbonate: A Versatile Renewable Synthon

INTRODUCTION been investigated using lipase-catalysed acetylation and/or alcoholysis [5a]. More recently, self-condensation to oligomers has been explored [6], but little has been developed on chemical transformations of 2 when treated with various nucleophiles. Our interest is focused on the versatility of such an activated form of glycerol as a multielectrophilic synthon in which the primary hydroxyl group can also be activated (Scheme 2). Glycerol carbonate might Valorisation of glycerol 1 is becoming a crucial challenge for industrial companies: this small molecule appears as a major side-product during manufacturing of bio-diesels, fatty acids and surfactants [1]. This abundant and renewable itol is a prochiral C-3 synthon which has been widely investigated and used as raw material [2]. Among the glycerol-based

Synthesis of new functionalized aziridine-2- and azetidine-3-carboxylic acid derivatives of potential interest for biological and foldameric applications.

A short synthesis of alkyl 2-(bromomethyl)aziridine-2-carboxylates and alkyl 3-bromoazetidine-3-carboxylates was developed involving amination, bromination, and base-induced cyclization of alkyl 2-(bromomethyl)acrylates. The aziridines are the kinetically favored cyclization products and could be transformed into 3-bromoazetidine-3-carboxylic acid derivatives via thermal isomerization. The new small-membered azaheterocyclic α- and β-amino acid derivatives contain a bromo-substituted carbon center as a useful moiety for functionalization. Transformation of these functionalized azaheterocycles via nucleophilic substitution with carbon, sulfur, oxygen, and nitrogen nucleophiles and via elaboration of the amino and carboxyl group provided a broad range of new conformationally constrained aziridine-2- and azetidine-3-carboxylic acid derivatives, which are of interest from a biological point-of-view as well as for applications in the field of foldamers.

Inhibition of the D-fructose transporter protein GLUT5 by fused-ring glyco-1,3-oxazolidin-2-thiones and -oxazolidin-2-ones

The glucose transporter 5 (GLUT5)-a specific D-fructose transporter-belongs to a family of facilitating sugar transporters recently enlarged by the human genome sequencing. Prompted by the need to develop specific photolabels of these isoforms, we have studied the interaction of conformationally locked D-fructose and L-sorbose derived 1,3-oxazolidin-2-thiones and 1,3-oxazolidin-2-ones to provide a rational basis for an interaction model. The inhibition properties of the D-fructose transporter GLUT5 by glyco-1,3-oxazolidin-2-thiones and glyco-1,3-oxazolidin-2-ones is now reported. In vitro, the fused-rings systems tested showed an efficient inhibition of GLUT5, thus bringing new insights on the interaction of D-fructose with GLUT5.

Base-modified nucleosides from carbohydrate derived oxazolidinethiones: a five-step process

Abstract Starting from unprotected carbohydrates, base-modified nucleosides could be reached in four steps through the condensation of anthranilic acid with a suitably protected sugar-derived 2-alkylthio-1,3-oxazoline.

Stereoselectivity in the construction of rigidified homoserine analogues

Abstract Methyl substituted cyclohexyl-1-amino-3-hydroxy-1-carboxylic acid derivatives have been prepared from 5,5-tethered dienes of (2 R )-2,5-dihydro-2-isopropyl-3,6-dimethoxypyrazine in stereoselective syntheses. Ring closing metathesis reaction of the diene 2 afforded a heterospirenone which was the substrate for conjugate addition with an alkyl cuprate. Reduction of the adduct followed by hydrolytic cleavage of the heterocyclic ring provided a cyclic α-amino acid derivative. The absolute configuration at the new stereocenters in the products were established by X-ray crystallography analyses.

Highly efficient and chemoselective α-iodination of acrylate esters through Morita–Baylis–Hillman-type chemistry

The chemoselective α-iodination of various simple and multi-functionalised acrylic esters is efficiently accomplished by a Morita-Baylis-Hillman protocol involving the use of N-iodophthalimide, 3-quinuclidinol and KF-Celite in acetonitrile. No degradation of the obtained compounds was observed under the optimized conditions thus, furnishing α-iodoacrylates suitable for organometallic reactions (i.e. Nozaki-Kishi-Hiyama type coupling).

Sonogashira Coupling Offers a New Synthetic Route to Thieno[2,3-c]pyrazoles

Abstract 1,3-Disubstituted-5-chloro-4-iodopyrazoles are selectively coupled with phenylacetylene under typical Sonogashira reaction conditions [PdCl2(PPh3)2, CuI, Et3N, dimethylformamide (DMF)] to obtain the corresponding 5-chloro-4-(phenylethynyl)pyrazoles in good yield. The latter are smoothly cyclized with Na2S in DMF into the corresponding thieno[2,3-c]pyrazoles. Detailed spectroscopic investigations (1H, 13C, and 15N NMR, mass, and infrared) of all compounds are reported.

Colorimetric Cyanide Chemosensor Based on 1',3,3',4-Tetrahydrospiro[chromene-2,2'-indole].

A new class of chemosensors based on the 1′,3,3′,4-tetrahydrospiro[chromene-2,2′-indole] ring system, which detects cyanide with high specificity, is described. These chemosensors show a distinct color change when treated with cyanide in acetonitrile solution buffered with sodium phosphate, and this procedure is not affected by the presence of other common anions. The chemisensors exhibit high sensitivity to low concentrations of cyanide, meeting the European Union water quality control criterion of sensitivity below 0.05 mg L−1, and show a very fast response within tens of seconds. The mechanism for detection is rationalized by the nucleophilic substitution of the phenolic oxygen atom at the indoline C-2 atom by the cyanide anion to form a stable indolylnitrile adduct and to generate the colored 4-nitrophenolate chromophore. These chemosensors can be synthesized by a simple procedure from commercially available starting materials.

Synthesis of functionalised indoline spiropyrans by condensation of indolo[2,1-b][1,3]benzoxazines with ortho-hydroxy-substituted aromatic aldehydes

Condensation of 5a,6-dihydro-5a,6,6-trimethyl-2-nitro-12H-indolo[2,1-b][1,3]benzoxazine derivatives with ortho-hydroxy-substituted aromatic aldehydes afforded 1′-(2-hydroxy-5-nitrobenzyl)spiro[1-benzopyran-2,2′-indoline].

Synthesis of alkyl 3-chloroazetidine-3-carboxylates via regioselective ring transformation of alkyl 2-(bromomethyl)aziridine-2-carboxylates

The synthesis of alkyl 3-chloroazetidine-3-carboxylates was developed by ring transformation of alkyl 2-(bromomethyl)aziridine-2-carboxylates utilizing ring opening with hydrochloric acid at the more sterically hindered carbon atom of the aziridine ring and subsequent base-promoted ring closure.