LiAlH4 -Induced Selective Ring Rearrangement of 2-(2-Cyanoethyl)aziridines toward 2-(Aminomethyl)pyrrolidines and 3-Aminopiperidines as Eligible Heterocyclic Building Blocks.

2-(2-Cyanoethyl)aziridines and 2-aryl-3-(2-cyanoethyl)aziridines were deployed as substrates for an In(OTf)3 -mediated regio- and stereoselective ring rearrangement upon treatment with LiAlH4, affording a variety of novel 2-(aminomethyl)pyrrolidines and 3-aminopiperidines, respectively. Further synthetic elaboration of the obtained 3-aminopiperidines resulted in the formation of a peculiar and unexplored conformationally constrained imidazolidinone and diketopiperazine scaffold.

Synthesis of 2-aminomethyl-4-phenyl-1-azabicyclo[2.2.1]heptanes via LiAlH₄-induced reductive cyclization of 2-(4-chloro-2-cyano-2-phenylbutyl)aziridines and evaluation of their antimalarial activity.

2-(4-Chloro-2-cyano-2-phenylbutyl)aziridines were employed for the one-step stereoselective construction of both endo- and exo-2-aminomethyl-4-phenyl-1-azabicyclo[2.2.1]heptanes as new azaheterobicyclic scaffolds via a double LiAlH(4)-induced reductive cyclization protocol.

Radical-mediated nitrile translocation as the key step in the stereoselective transformation of 2-(4-chloro-2-cyanobutyl)aziridines to methyl cis-(1-arylmethyl-4-phenylpiperidin-2-yl)acetates.

Non-activated 2-(4-chloro-2-cyano-2-phenylbutyl)aziridines were used as building blocks for the stereoselective synthesis of novel cis-2-cyanomethyl-4-phenylpiperidines via a microwave-assisted aziridine to piperidine ring expansion followed by a radical-induced nitrile translocation through initial formation and subsequent cleavage of intermediate bicyclic iminyl radicals. Furthermore, these 2-(cyanomethyl)piperidines were shown to be eligible substrates for the preparation of methyl cis-(1-arylmethyl-4-piperidin-2-yl)acetates through a Pinner reaction using gaseous HCl in methanol.

Synthesis of 2-amino-3-arylpropan-1-ols and 1-(2,3-diaminopropyl)-1,2,3-triazoles and evaluation of their antimalarial activity.

A variety of 2-amino-3-arylpropan-1-ols, anti-2-amino-3-aryl-3-methoxypropan-1-ols and anti-2-amino-1-arylpropan-1,3-diols were prepared selectively through elaboration of trans-4-aryl-3-chloro-β-lactams. In addition, a number of 2-(azidomethyl)aziridines was converted into novel 2-[(1,2,3-triazol-1-yl)methyl]aziridines by Cu(I)-catalyzed azide-alkyne cycloaddition, followed by microwave-assisted, regioselective ring opening by dialkylamine towards 1-(2,3-diaminopropyl)-1,2,3-triazoles. Although most of these compounds exhibited weak antiplasmodial activity, six representatives showed moderate antiplasmodial activity against both a chloroquine-sensitive and a chloroquine-resistant strain of Plasmodium falciparum with IC(50)-values of ≤25 μM.

Chemical and enzymatic synthesis of 2-(2-carbamoylethyl)- and 2-(2-carboxyethyl)aziridines and their conversion into δ-lactams and γ-lactones.

Treatment of 1-arylmethyl-2-(2-cyanoethyl)aziridines with a nitrile hydratase afforded the corresponding 2-(2-carbamoylethyl)aziridines, which underwent rearrangement into 5-hydroxypiperidin-2-ones upon heating under microwave irradiation. In addition, treatment of 2-(2-cyanoethyl)aziridines with a nitrilase selectively afforded 5-hydroxypiperidin-2-ones in good yields. On the other hand, chemical hydrolysis of 2-(2-cyanoethyl)aziridines using KOH in EtOH/H(2)O furnished the corresponding potassium 3-(aziridin-2-yl)propanoates, which, upon acidification with acetic acid, smoothly rearranged into 4-(aminomethyl)butyrolactones.

Reactivity of activated versus nonactivated 2-(bromomethyl)aziridines with respect to sodium methoxide: a combined computational and experimental study.

The difference in reactivity between the activated 2-bromomethyl-1-tosylaziridine and the nonactivated 1-benzyl-2-(bromomethyl)aziridine with respect to sodium methoxide was analyzed by means of DFT calculations within the supermolecule approach, taking into account explicit solvent molecules. In addition, the reactivity of epibromohydrin with regard to sodium methoxide was assessed as well. The barriers for direct displacement of bromide by methoxide in methanol are comparable for all three heterocyclic species under study.

Synthesis of 2-(aminomethyl)aziridines and their microwave-assisted ring opening to 1,2,3-triaminopropanes as novel antimalarial pharmacophores.

A variety of 2-(aminomethyl)aziridines was prepared and converted into the corresponding 1,2,3-triaminopropanes through a novel, microwave-assisted and regioselective ring opening by diethylamine in acetonitrile. Antiplasmodial assays revealed antimalarial activity for 2-[(1,2,4-triazol-1-yl)methyl]aziridines and 2-(N,N-diethylaminomethyl)aziridines, as well as for the corresponding 1-(diethylamino)propanes obtained through ring opening, pointing to the relevance of both the 2-(aminomethyl)aziridine and the 1,2,3-triaminopropane unit as novel antimalarial pharmacophores.

Synthesis of stereodefined piperidines from aziridines and their transformation into conformationally constrained amino acids, amino alcohols and 2,7-diazabicyclo[3.3.1]nonanes.

2-(2-Cyano-2-phenylethyl)aziridines were converted into novel cis- and trans-2-chloromethyl-4-phenylpiperidine-4-carbonitriles via alkylation with 1-bromo-2-chloroethane followed by microwave-assisted 6-exo-tet cyclization and regiospecific ring opening. The latter piperidines were used as eligible substrates for the synthesis of stereodefined 2-chloromethyl-, 2-hydroxymethyl-, and 2-carboxymethyl-4-phenylpiperidine-4-carboxylic acids, 2-hydroxymethyl-4-phenylpiperidine-4-carbonitriles, 3-hydroxy-5-phenylazepane-5-carbonitriles, and 5-phenyl-2,7-diazabicyclo[3.3.

A new approach towards 1-phenyl and 1-benzyl substituted 2-(aminomethyl)cyclopropanecarboxamides as novel derivatives of the antidepressant Milnacipran.

2-(2-Cyano-2-phenylethyl)aziridines were converted into novel trans-2-aminomethyl-1-phenylcyclopropanecarboxamides via regiospecific ring opening and 3-exo-tet cyclisation, thus providing the first convenient entry into the trans-isomer of Milnacipran as a useful template for further derivatisation. Furthermore, unprecedented 2-aminomethyl-1-benzylcyclopropanecarboxamides have been synthesized using two different routes starting from 2-(2-cyanoethyl)aziridines, both involving alpha-benzylation with respect to the nitrile group and aziridine to cyclopropane ring transformation.

Synthesis of 1-arylmethyl-2-(2-cyanoethyl)aziridines and their rearrangement into novel 2-(aminomethyl)cyclopropanecarbonitriles.

1-Arylmethyl-2-(bromomethyl)aziridines were transformed into novel 2-(2-cyanoethyl)aziridines upon treatment with alpha-lithiated trimethylsilylacetonitrile in THF in an efficient and straightforward approach. The latter aziridines underwent ring opening by reaction with benzyl bromide in acetonitrile, affording 5-amino-4-bromopentanenitriles through a regiospecific ring opening of intermediate aziridinium salts by bromide. Further elaboration of these gamma-bromonitriles resulted in the synthesis of novel 2-[N,N-bis(arylmethyl)aminomethyl]cyclopropanecarbonitriles in high yields by means of a 1,3-cyclization protocol upon treatment with KOtBu in THF.