Studies on the synthesis of orthogonally protected azalanthionines, and of routes towards β-methyl azalanthionines, by ring opening of N-activated aziridine-2-carboxylates

The regioselective Wacker oxidation of internal allylamines: synthesis of functionalized and challenging β-amino ketones

A convenient and general protocol for the palladium-catalysed oxidation of internal allylamine derivatives to β-amino ketones is reported. The transformation occurs at room temperature and shows a wide substrate scope as well as high functional group and N-protecting group tolerance. We also describe potential applications of the method, e.g., the synthesis of bioactive molecules or simple transformations of selected β-amino ketones into other interesting building blocks.

Discovery of steroidal lactam conjugates of POPAM-NH2 with potent anticancer activity

Aim: Steroidal prodrugs of nitrogen mustards such as estramustine and prednimustine have proven effective anticancer agents in clinical use since the 1970s. In this work, we aimed to develop steroidal prodrugs of the novel nitrogen mustard POPAM-NH2. POPAM-NH2 is a melphalan analogue that was coupled with three different steroidal lactams. Methodology: The new conjugates were preclinically tested for anticancer activity against nine human and one rodent cancer experimental models, in vitro and in vivo. Results & conclusion: All the steroidal alkylators showed high antitumor activity, in vitro and in vivo, in the experimental systems tested. Moreover, these hybrid compounds showed by far superior anticancer activity compared with the alkylating agents, melphalan and POPAM-NH2.

Nucleophilic ring opening reactions of aziridines

Aziridine ring opening reactions have gained tremendous importance in the synthesis of nitrogen containing biologically active molecules. During recent years, a great effort has been put forward by scientists toward unique bond construction methodologies via ring opening of aziridines. In this regard, a wide range of chiral metal- and organo-catalyzed desymmetrization reactions of aziridines have been reported with carbon, sulfur, oxygen, nitrogen, halogen, and other nucleophiles. In this review, an outline of methodologies adopted by a number of scientists during 2013-2017 for aziridine ring opening reactions as well as their synthetic applications is described.

Conformational-dependent reaction mechanism: case of acid hydrolysis ofN-benzoyl-9-azabicyclo[6.1.0]non-4-ene

Quantum chemical studies of the acid hydrolysis of cis-cis-N-benzoyl-9-azabicyclo[6.1.0]non-4-ene in gas phase and sulfuric acid solution have been carried out. Conformational analysis of reactant and intermediates were done at DFT level of calculations, using different basis sets. Transition states were identified and IRC calculations were done at the same level. In the first step of the reaction, the protonation occurs preferentially on the nitrogen atom. Three products are obtained. The type of mechanism, stepwise or concerted, depends on the stable conformers and the cleaved N–C bond. The main conclusion is that the products of the reaction depend on the nature of the stable conformer of the reactant.

Synthesis of β-substituted tryptamines by regioselective ring opening of aziridines

Functionalized tryptamines are targets of interest for development as small molecule therapeutics. The ring opening of aziridines with indoles is a powerful method for tryptamine synthesis if site selectivity can be controlled. 4-Nitrobenzyl carbamate (PNZ)-protected aziridines undergo regioselective ring opening to produce β-substituted tryptamines for a series of indoles. The PNZ-protected tryptamines can be further manipulated by PNZ removal under mild conditions.

Aziridine electrophiles in the functionalisation of peptide chains with amine nucleophiles

We describe herein the synthesis of aziridine-containing amino acids embedded within tripeptide structures.