Antonella Capperucci

Bis(trimethylsilyl)sulfide based thionation of carbonyl compounds : synthesis of thioketones

Abstract A wide range of thioketones may be conveniently obtained by silyl triflate promoted bis(trimethylsilyl)sulfide thionation of ketones.

Organosilane‐Induced Synthesis and Functionalization of Sulfur‐Containing Compounds

Reactions of organothiosilanes with organic substrates generally lead to delivery of a sulfur moiety onto the target molecule, the precise outcome being related to the structure of the silyl sulfide used. Aromatic and aliphatic silyl sulfides react with carbonyl compounds under acidic or basic conditions to afford thioacetals and thioketals, but reactions with more activated compounds such as α,β-unsaturated acylsilanes give the Michael adducts, which represent versatile intermediates in organic synthesis. Silyl sulfides can also participate in substitution reactions of silyl enol ethers to afford vinyl sulfides. On the contrary, hexamethyldisilathiane reacts with various carbonyl compounds under the catalysis of CoCl2·6H2O or CF3SO3SiMe3 with thionation of the carbonyl unit, thereby providing a general access to thioketones and thioaldehydes, which can be trapped in situ by dienes. The use of CF3SO3SiMe3 in the reaction with cyclohexadiene gives rise to the interesting feature that stereopredetermined access to either the endo or the exo isomer can be obtained. Furthermore, when using aromatic or heteroaromatic o-azidoaldehydes, the reactivity of hexamethyldisilathiane may be finely tuned to drive the reaction towards the synthesis of o-azidothioaldehydes, fused isothiazole ring systems, or aromatic and heteroaromatic o-amino aldehydes and o-amino thioaldehydes. Lastly, by taking advantage of the high reactivity of the C−Si bond under fluoride ion catalysis, selective regiospecific thiophilic functionalizations of thioketones, dithioesters, trithiocarbonates, and their sulfines by various organosilanes such as allylsilanes, benzylsilane, and α-hetero-substituted silyl nucleophiles can be realized.

Stannylcupration of γ-heterosubstituted acetylenic esters: A new route to 4-stannylated five membered N- and O- heterocycles

Abstract 4-Tributylstannyl,2-(5H)-furanone and pyrrolone have been prepared in good yields by addition of mixed stannylcuprate reagent on γ-amino and γ-hydroxy acetylenic esters. The use of these compounds as useful intermediates for the selective functionalization of these heterocyclic rings is discussed.

2-Trimethylsilyl-1,3-dithiolane as a masked dithiolane anion

Abstract 2-Trimethylsilyl-1,3-dithiolane, easily obtainable through transthioacetalization of corresponding silylated acetals, can be efficiently reacted, under fluoride-ion catalysis, with different organic electrophiles, leading to a general and mild functionalization protocol. This reactivity discloses the ability of compound 3 to act as a masked dithiolane anion.

Evaluation of selenide, diselenide and selenoheterocycle derivatives as carbonic anhydrase I, II, IV, VII and IX inhibitors

A series of selenides, diselenides and organoselenoheterocycles were evaluated as carbonic anhydrase (CA, EC 4.2.1.1) inhibitors against the human (h) isoforms hCA I, II, IV, VII and IX, involved in a variety of diseases among which glaucoma, retinitis pigmentosa, epilepsy, arthritis and tumors etc. These investigated compounds showed inhibitory action against these isoforms and some of them were selective for inhibiting the cytosolic over the membrane-bound isoforms, thus making them interesting leads for the development of isoform-selective inhibitors.

Silicon in organosulphur chemistry. Part 2. Synthesis of unsymmetrical disulphides

Abstract Unsymmetrical aryl- and alkyl- disulphides are prepared from silylsulphides and thiosulphinates or thiosulphonates. Silyl sulphinic esters are also obtained in the reaction of the thiosulphonates.

Azide cyclizations with acetylenic silyl ketone: a general access to functionalized-1,2,3-triazolylacylsilanes and aldehydes

Abstract Reaction of several azido compounds with acetylenic silyl ketone affords a simple and direct entry to triazolylacylsilanes and, alter desilylation to the corresponding functionalized triazolylaldehydes

Silylcupration of N-phenyl-N-ethynyl-aniline: A versatile route to functionalized N,N-bis(phenyl)enamines

Abstract The silylcupration of N-phenyl-N-ethynyl-aniline, occurs regioselectively leading to silylation at the β-carbon atom. Subsequent reaction of the resulting vinyl copper adduct with electrophiles, opens a new flexible route to functionalized enamines.

Silicon in organosulphur chemistry. Part 1. Synthesis of trisulphides

Abstract The reaction of bis(trimethylsilyl)sulphide with thiosulphinates and thiosulphonates in an inert solvent under neutral and mild conditions gives symmetrical alkyl- or aryl-trisulphides.

Composition and mean residence time of molecular weight fractions of organic matter extracted from two soils under different forest species

The organic matter extracted from various mineral horizons of two forest soils, one under silver fir (Abies alba Mill.), the other under European beech (Fagus sylvatica L.), was fractionated by dialysis into three fractions, 100–1000, 1000–8000, and >8000 Da. On a C basis, in all horizons the recovered organic matter amounted to less than a half of the total and was mainly composed of molecules >8000 Da. The 100–1000 Da fraction had a principal elemental composition profoundly different from the other two fractions, which, instead differed from each other significantly only for the S content and the molar ratio of C with N. No significant difference in this regard was found between soils. The richness in O and some typical absorption bands in the FT-IR spectra indicated that the 100–1000 Da fraction had a lot of carboxyl moieties. The spectroscopic (13C NMR) investigation showed that the 1000–8000 and >8000 Da fractions had a prevalently aliphatic nature and signals attributable to polysaccharides (O-alkyl C) revealed overall a high presence of non-humic biopolymers. These latter were significantly more abundant, suggesting a lower degree of humification, in the >8000 Da fraction than in the 1000–8000 Da fraction. Comparing soils, that under beech appeared significantly richer in O-alkyl C than that under fir. The organics extracted from the A horizon of both soils had positive Δ14C values, indicating recent synthesis mainly due to the present forest cover. The mean residence time (MRT) of the combined 100–1000 Da and 1000–8000 Da fractions and the >8000 Da fraction increased with depth, even to about 5000 years in the more than 1-m deep BC horizons under beech. In some cases, and especially in the soil under fir, despite higher values of δ13C denoting stronger microbial decomposition, the 100–8000 Da fraction showed a higher MRT than that of the >8000 Da fraction, perhaps due to its ascertained lower content of non-humic biopolymers.