One-Pot Synthesis of Weinreb Amides Employing 3,3-Dichloro-1,2-Diphenylcyclopropene (CPI-Cl) as a Chlorinating Agent

The synthesis of Na -protected amino alkyl Weinreb amides starting from the corresponding a-amino acids as well as carboxylic acids has been delineated through the in situ generation of acid chlorides using CPI-Cl as a chlorinating agent. The protocol is simple; the reaction conditions employed were mild, and compatible with all the three commonly used urethane protecting groups namely, Boc, Cbz and Fmoc groups. The resulting Weinreb amides are obtained in good yields as optically pure products

Montmorillonite K-10 supported palladium nanoparticles: A catalyst for the preparation of α-aminoynones employing copper free acyl Sonogashira reaction

977-982Palladium nanoparticles supported by Montmorillonite K-10 (MMT K-10) are utilized for the synthesis of α-amino ynones using amino acid chlorides and a mild base at room temperature. All the compounds were obtained in good yields. Furthermore, the catalyst is also utilized for the deprotection of protecting groups operating in peptide chemistry

Montmorillonite K-10 supported palladium nanoparticles: A catalyst for the preparation of α-aminoynones employing copper free acyl Sonogashira reaction

Palladium nanoparticles supported by Montmorillonite K-10 (MMT K-10) are utilized for the synthesis of α-amino ynones using amino acid chlorides and a mild base at room temperature. All the compounds were obtained in good yields. Furthermore, the catalyst is also utilized for the deprotection of protecting groups operating in peptide chemistry.

Peptide Bond Formation via Nα-Protected Diacyldiselenides

Abstract A simple, straightforward, for the peptide bond formation employing corresponding carboxylic acids and amines derived from amino acids via Nα -protected diacyldiselenide is delineated. The key step of the synthesis is the in situ generation of Nα -protected diacyldiselenide using NaBH2Se3 as selenating reagent, followed by trapping with an amino acid ester leading to the peptide. The formation of Nα -protected diacyldiselenide was confirmed through TLC and HRMS analysis using crude sample. The reaction is clean and all the products were obtained in moderate to good yields, including for sterically hindered amino acids. The protocol is free from racemisation, compatible with Fmoc, Cbz and Boc groups

Synthesis of carbodiimides from 1,3-disubstituted selenoureas by iodine-mediated deselenization

1291-1294A facile one-pot synthesis of symmetrical and unsymmetrical carbodiimides from 1,3-disubstitued selenoureas by iodine mediated oxidative deselenization in high yields is reported. Advantages of the method include mild conditions, short duration, cost effective and environmentally benign iodine reagent, and wide substrate scope including the preparation of 1,3-dialkyl carbodiimides and simple work-up, purification of the products

Dehydration of Chiral α-Amides to Chiral α-Nitriles under the Appel Reaction Conditions

An efficient synthesis of Nα-protected amino nitriles from Nα-protected amino acid amides employing Ph3P, I2 and NMM was described. Various amino acid amides, protected by Fmoc, Z and Boc were conveniently converted to nitriles in high yields. Side chain protected amino acid amides were well-tolerated and a good yield of products was obtained. The protocol serves as one of the mild, among a few available, methods for the racemization-free conversion of Nα-protected amino acid amides to corresponding nitriles with neither harsh condition nor catalyst. Graphic Nα-protected amino acid amides were efficiently transformed to Nα-protected amino acid nitriles employing I2, PPh3, and NMM under mild reaction conditions. Fmoc, Boc and Cbz-protected amino acid amides were converted into their corresponding nitriles groups. Side chain protected amino acid amides also underwent facile conversion to their corresponding nitriles with good yields

Thionation of Di and Tripeptides Employing Thiourea as a Sulphur Transfer Reagent

A simple and efficient method for the synthesis of thiopeptides by the treatment of Nα-protected peptide esters employing DMF/PCl5 and thiourea as a sulphur transfer reagent is described. The conversion is carried out at room temperature within a short reaction time. The method is high yielding and free from racemization. Multiple thionation is demonstrated by conversion of two peptide bonds of tripeptides into thioamides. In addition, amino acid derived arylamides are also converted into aryl thioamides

Synthesis of an Amino Phosphinodiselenoic Acid Ester and β-Amino Diselenides Employing P2Se5

The synthesis of a new class of amino phosphinodiselenoic acid ester and β-amino diselenides is conducted by employing a reaction between Nβ-protected aminoalkyl iodide and phosphorus pentaselenide (P2Se5) has been described. In the presence of protic solvents, amino phosphinodiselenoic acid esters were found to be the major products, whereas β-amino diselenides were formed exclusively when the reaction was carried out in polar aprotic solvents

Synthesis of thioureido peptidomimetics employing alkyl azides and dithiocarbamates

An unprecedented approach for the assembly of thioureido peptidomimetics is developed employing alkyl azides and dithiocarbamates. Dithiocarbamates react with alkyl azides with the liberation of N2 and elemental sulfur thereby leading to thiourea in a traceless manner. Thioureido peptidomimetics are thus furnished in good yields with no epimerization. This process is mild, free from the use of a base, scalable and step economic. The practicability of this methodology has been highlighted by the synthesis of N,N′-orthogonally protected thioureido peptidomimetics