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An efficient one-step synthetic strategy was used to prepare a set of dicarboxamides through palladium-catalysed amino carbonylation of iodoalkenyl and iodoaryl compounds, with use of various alkyl- and aryldiamines as N-nucleophiles. The isolated yields of the dicarboxamides depended signifi cantly on the iodo substrate and diamine structures, as well as on the reaction conditions, the best one (ca. 70 %) being achieved with 1-iodocyclohexene as substrate and 1,4-di aminobutane as nucleophile, at 100 °C and 30 bar of CO. When iodobenzene was used as model aryl halide, the high est yield of the target dibenzamides (ca. 65 %) was obtained with 1,4-diaminobenzene as coupling amine, at 100 °C and 10 bar of CO. Preliminary studies on their in vitro cytotoxicity against human lung carcinoma A549 cells showed N,N�- (butane-1,4-diyl)dibenzamide and androst-16-ene-based di carboxamides to be the most efficient cytotoxic agents, with IC50values of approximately 40μM.

Novel androstene-based dimers linked through A- and D-ring with 3,3′- and 17,17′-dicarboxamide spacers, were synthesized via palladium-catalyzed aminocarbonylation. Androstane derivatives possessing either 3-iodo-3,5-diene or 17-iodo-16-ene functionality were used as substrates in the presence of palladium-phosphine in situ catalysts and aliphatic and aromatic diamines as N-nucleophiles. Since androst-4-ene-3,17-dione was used as starting material, a multistep synthesis including protection/deprotection of one of the keto functionalities (3-one or 17-one) as ethylene ketals, transformation of the other keto group to iodoalkene functionality via its hydrazone, and palladium-catalyzed aminocarbonylation of the iodoalkene functionality was used. In this way, new dimeric compounds possessing a keto functionality were obtained in moderate-to-good isolated yields, via highly chemoselective reactions, under relatively mild conditions.

3,17-Dicarboxamido-androst-3,5,16-triene derivatives possessing various amine moieties were synthesized under mild conditions using palladium-catalyzed homogeneous aminocarbonylation as key reaction. Compounds containing the corresponding iodoalkene functionalities, i.e., 17-iodo-16-ene and 3-iodo-3,5-diene structural motifs, were used in the aminocarbonylation and the N -nucleophiles were varied systematically. Three amines, such as tert -butylamine, piperidine and methyl alaninate were used as N -nucleophiles in the aminocarbonylation. All variations of 3,17-dicarboxamides were synthesized using this methodology. Androst-4-ene-3,17-dione was used as starting material. The synthetic strategy of the multistep synthesis was based on the systematic variation and consecutive use of three different reactions: (i) the protection/deprotection of one of the keto functionalities (3-one or 17-one) as ethylene ketals, (ii) the transformation of the other keto group to iodoalkene functionality via its hydrazone, and (iii) palladium-catalyzed aminocarbonylation of the iodoalkene functionality.

3,17-Dicarboxamido-androst-3,5,16-triene, 3-carboxamido-androst-3,5-dien-17-one, 17-carboxamido-androst-4,16-dien-3-one and 11-carboxamido-androst-5,9(11)-dien-3,17-dione derivatives were synthesized in homogeneous carbonylation reactions from the corresponding 3,17-diiodo-androst-3,5,16-triene, 3-iodo-androst-3,5-diene-17-ethylene ketal, 17-iodo-androst-5,16-dien-3-ethylene ketal, 11-iodo-androst-5,9(11)-diene-3,17-bis(ethylene ketal) derivatives, respectively. A highly chemoselective palladium-catalyzed aminocarbonylation of the corresponding iodo-alkene, carried out under mild reaction conditions, can be considered as the key-step for the introduction of the carboxamide functionalities. The synthesis of the iodo-alkene substrate is based on the transformation of the corresponding keto derivative to hydrazone, which was treated with iodine in the presence of a base (1,1,3,3-tetramethyl guanidine). The aminocarbonylation reaction is highly tolerant towards the N-nucleophiles, i.e. various primary and secondary amines including amino acid methyl esters can also be used.

A versatile and atom-economical route to alkenyl and aryl dicarboxamides by catalytic aminocarbonylation is described.