PubMed Health⌕ Search

Biomedical subjects

Andrea Porcheddu

Publications and source records attributed to Andrea Porcheddu.

15 recordsLinked to original sources
PubMed2006

Angeli-Rimini's reaction on solid support: a new approach to hydroxamic acids.

Angeli-Rimini's reaction has been performed for the first time on solid phase. A convenient one-step procedure for the synthesis of hydroxamic acids starting from aldehydes and solid-supported N-hydroxybenzenesulfonamide is reported. The hydroxamates are isolated in good to high yields and purities by simple evaporation of the volatile solvents, after treatment of the crude reaction mixture with sequestering agents.

Aldehydes↗
PubMed2005

Peptide nucleic acids (PNAs), a chemical overview.

Peptide nucleic acid (PNA) is a nucleic acid analogue and a fully synthetic DNA/RNA-recognising ligand with a neutral peptide-like backbone. In spite of the large change on the backbone structure, PNA molecules bind strongly to complementary DNA and RNA sequences. Originally conceived as ligand for the recognition of double stranded DNA, the unique physico-chemical properties of PNAs have led to the development of a variety of research and diagnostic assays. The extraordinary properties of PNA may advance routine clinical tests and environmental analyses that will utilise the PNA technology. PNAs may also have an impact on in situ hybridisation, cytogenetics and industrial microbiology. This paper presents some recent achievements on peptide nucleic acids and discusses, from the viewpoint of literature, what the potential is and what the limitations of such compounds are. This review, which is not intended to be exhaustive, is mostly aimed at the current progress in PNA chemistry, structure, and hybridisation, highlighting some applications too.

Amination↗
PubMed2004

A new polymer-supported reagent for the synthesis of beta-lactams in solution.

A modified Mukaiyama reagent was prepared on a PS-DVB resin. This reagent was used for the preparation of beta-lactams, using the Staudinger reaction. The products were obtained by generating the ketene from a carboxylic acid under sonication with the resin followed by reaction with the imine. Excess of the imine was removed by reduction followed by acid scavenging.

Indicators and Reagents↗
PubMed2004

New cellulose-supported reagent: a sustainable approach to guanidines.

[reaction: see text] A new cellulose-supported reagent for the synthesis of guanidine in aqueous medium is reported starting from commercially available functionalized cellulose beads. Primary and secondary amines, anilines, and amino acids were transformed to the corresponding guanidines in high yields and under very mild conditions.

Amines↗
PubMed2003

Simple one-flask method for the preparation of hydroxamic acids.

[reaction: see text] A one-step conversion of carboxylic acids to hydroxamic acids under very mild conditions is described. This simple and efficient method has been applied for the synthesis of enantiopure hydroxamate of alpha-amino acids and peptides.

Carboxylic Acids↗
PubMed2003

Trichloroisocyanuric/TEMPO oxidation of alcohols under mild conditions: a close investigation.

Efficient oxidation of primary alcohols to the corresponding carboxylic acids can be carried out at room temperature and in acetone/water, using trichloroisocyanuric acid (TCCA) in the presence of catalytic TEMPO. The mild conditions of this procedure and the total absence of any transition metal make this reaction suitable for safe laboratory use. A possible mechanism is presented and discussed.

Journal Article↗
PubMed2002

Beckmann rearrangement of oximes under very mild conditions.

A variety of ketoximes, easily prepared from the corresponding ketones, undergo the Beckmann rearrangement upon treatment with 2,4,6-trichloro[1,3,5]triazine in N,N-dimethylformamide at room temperature in excellent yields. This procedure can be applied to aldoximes for obtaining the corresponding nitriles.

Journal Article↗
PubMed2002

Mild and highly selective formyl protection of primary hydroxyl groups.

Efficient conversion of primary alcohols to the corresponding formate esters can be carried out at room temperature in methylene chloride, using 2,4,6-trichloro-1,3,5-triazine and N,N-dimethylformamide in the presence of lithium fluoride. This procedure appears as a valid method for selectively protecting primary hydroxyl groups.

Journal Article↗
PubMed2002

An efficient route to alkyl chlorides from alcohols using the complex TCT/DMF.

[reaction: see text] Efficient conversion of alcohols and beta-amino alcohols to the corresponding chlorides (and bromides) can be carried out at room temperature in methylene chloride, using 2,4,6-trichloro[1,3,5]triazine and N,N-dimethyl formamide. This procedure can also be applied to optically active carbinols.

Journal Article↗
PubMedDate not supplied

Cellulose beads: a new versatile solid support for microwave- assisted synthesis. Preparation of pyrazole and isoxazole libraries.

The synthesis of libraries of substituted pyrazoles and isoxazoles has been developed via in situ generation of polymer-bound enaminones. The synthetic protocol makes use of commercially available aniline cellulose, a low-cost and versatile biopolymer, under very mild conditions. This new support allowed us to carry out reactions in polar solvents under both conventional heating and MW irradiation without degradation of the polymer. The reaction between cellulose-bound enaminone and hydroxylamine or hydrazines to afford the target heterocycles in high yields directly in solution is the key step. The support can be conveniently recycled.

Cellulose↗
PubMedDate not supplied

A "catch and release" strategy for the parallel synthesis of 2,4,5-trisubstituted pyrimidines.

A resin capture and release strategy for making a combinatorial array of 2,4,5-trisubstituted pyrimidines is demonstrated by capturing beta-ketoesters and beta-ketoamides on a solid-supported piperazine. Through a cyclocondensation reaction, the solid-supported enaminone is reacted with several guanidines under heating or microwave irradiation affording the corresponding pyrimidines in good yield and chemical purity directly on solution. After this final step, the support can be effectively recycled.

Journal Article↗
PubMedDate not supplied

Colorimetric tools for solid-phase organic synthesis.

One of the unresolved problems of solid-phase organic synthesis (SPOS) is the availability of general and rapid methods to monitor the transformation of functional groups present in molecules supported on insoluble supports. Color tests, far from providing the ultimate solution, may help in detection (and sometimes in quantification) of different functional groups. In this short review, we have collected most of the methods available and applied in SPOS with an Experimental Section that describes the procedure we have successfully applied to bead analyses in our laboratories.

Journal Article↗
PubMedDate not supplied

Synthesis of 1-alkyl-4-imidazolecarboxylates: a catch and release strategy.

The novel alkyl N-methyl-N-polystyreneamino-2-isocyanoacrylate was used for the synthesis of 1-substituted imidazole-4-carboxylates utilizing a "catch and release" methodology. The reactions were performed under microwave irradiation, affording the title compounds in both high yields and chemical purity directly to solution, from the solid phase support.

Journal Article↗