Josefina Quirante

Synthesis of 2-azabicyclo[3.3.1]nonanes by means of (carbamoyl)dichloromethyl radical cyclization

Abstract A new procedure for the synthesis of 2-azabicyclo[3.3.1]nonanes by intramolecular carboradical cyclization of 4-(trichloroacetamido)cyclohexenes substituted with an electron withdrawing substituent (ester or nitrile) is described. The procedure allows the preparation of synthetically interesting azabicyclos 14 and 15 in nearly 70% yield.

Isatin derivatives, a novel class of transthyretin fibrillogenesis inhibitors

The isatin core structure was found to be a novel chemical scaffold in transthyretin (TTR) fibrillogenesis inhibitor design. Among the series of isatin analogues prepared and tested, the nitro compound 1,3-dihydro-3-[(4-nitrophenyl)imino]-2H-indol-2-one (2r) is as potent as triiodophenol, which is one of the most active known TTR inhibitors. The E/Z stereochemistry of these molecules in solution, elucidated by (1)H NMR, does not influence their biological activity. The compounds do not bind to the native tetrameric TTR suggesting that their inhibitory action is independent of the protein binding and stabilization.

Diastereomerically pure platinum(II) complexes as antitumoral agents.: The influence of the mode of binding {(N), (N,O)- or (C,N)}- of (1S,2R)[(η5-C5H5)Fe{(η5-C5H4)CHNCH(Me)CH(OH)C6H5}] and the arrangement of the auxiliary ligands.

The study of the reactivity of (1S,2R) [(η(5)-C(5)H(5))Fe{[(η(5)-C(5)H(4)) CHNCH(Me)CH(OH)C(6)H(5)}] (1a) with cis-[PtCl(2)(DMSO)(2)] under different experimental conditions has allowed to isolate and characterize three pairs of isomeric and diastereomerically pure platinum(II) complexes. Two of the pairs are the trans- and cis- isomers of (1S,2R)[Pt{(η(5)-C(5)H(5))Fe[(η(5)-C(5)H(4))CHNCH(Me)CH(OH)C(6)H(5)]}Cl(2)(DMSO)] [trans-(2a) and cis-(3a), respectively], and of (1S,2R) [Pt{(κ(2)-N,O)(η(5)-C(5)H(5))Fe[(η(5)-C(5)H(4))CHNCH(Me)CH(O)C(6)H(5)]}Cl(DMSO)], {trans-(Cl, N) in (4a)} or a cis-(Cl, N) {in (5a)}; while the third one is formed by platinacycles: [Pt{(κ(2)-C,N[(η(5)-C(5)H(3))]CHN-CH(Me)CH(OH)C(6)H(5)]Fe(η(5)-C(5)H(5))}Cl(DMSO)] with different planar chirality [S(p) (in 6a) or R(p) (in 7a)]. The crystal structures of compounds 2a, 3a, 5a and 6a are also reported. The cytotoxic assessment of 1a-7a on lung (A549), breast (MDA-MB-231) and colon (HCT-116) cancer cell lines is also reported and reveals that the potency of the complexes is strongly dependent on the mode of binding of the iminoalcohol {(N) in 2a and 3a, (N,O)(-) in 4a and 5a or (C,N)(-) in 6a and 7a}, the relative arrangement of the monodentate ligands (in 2a-5a), and the planar chirality of the 1,2-ferrocenylunit in (6a and 7a). Among the new products (2a-7a), compounds 4a and 5a exhibit the highest potency with IC(50) values smaller than cisplatin in the three cancer cell lines assayed. Electrophoretic DNA migration studies in the presence of 2a-7a have been performed in order to get further insights into their mechanism of action. A comparative study of the solution behaviour of all the complexes in DMSO-d(6) or in DMSO-d(6):D(2)O (1:1) mixtures at 298 K is also reported.

Synthetic entry to 8-(o-nitrophenyl-2-azabicyclo[3.3.1]nonan-7-ones. Intermediates for the synthesis of strychnos-type systems.

Abstract The first synthetic route to 8-aryl-2-azabicyclo-[3.3.1]nonan-7-ones (e.g. 5) is reported. The synthesis involves acid cyclization of an appropriate 4-acetonyl-2-piperidinecarbonitrile (4) which, in turn, is obtained from the corresponding piperidine (3) by a modified Polonovski reaction. The o -nitrophenyl substituent of 3 is introduced by arylation of 4-piperidineacetoacetate 1 with o -fluoronitrobenzene followed by acid hydrolysis. The conversion of α-( o -nitrophenyl)ketone 5 to the bridged azocinoindole 7, an intermediate in the synthesis of deethyltubifolidine, is also reported.

Synthesis of enantiopure 2-azabicyclo[3.3.1]nonanes by a radical ring closure

Abstract The first synthesis of enantiomerically pure 2-azabicyclo[3.3.1]nonanes by an intramolecular radical reaction of the trichloroacetamido group bearing an ( S )- N -1-phenylethyl substituent with the silyl enol ether moiety in compounds 7 is described. The procedure allows the two enantiomers of the 2-azabicyclo[3.3.1]nonane-3,6-dione, 3 and ent - 3 , to be prepared separately. β-Lactam 8 and normorphan 9 are also formed from 7 through an initial radical translocation process in the cyclization step.

Functionalized 2-azabicyclo[3.3.1] nonanes. vii.: A new synthesis of 4-azatricyclo[5.2.2.04,8]undecan-11-one

Abstract An improved method for the synthesis of 4-azatricyclo [5.2.2.04,8] undecan-11-one (1) is reported. The synthesis involves hydrogenolysis of 8-hydroxyethyl-2-azabicyclo [3.3.1] nonan-7-one 3 followed by intramolecular alkylation of the resulting secondary amine 7. The required azabicyclic alcohol 3 was obtained by oxidative cyclization with mercuric acetate of the α-alkylated methyl 4-piperidineacetoacetate 5.

Cyclopalladated primary amines: a preliminary study of antiproliferative activity through apoptosis induction.

Twelve cyclometallated palladium(II) complexes containing primary aromatic amines [benzylamine (a), (R)-1-(1-naphthyl)ethylamine (b) and 2-phenylaniline (c)] as anionic bidentate (C,N)(-) ligands have been evaluated against a panel of human adenocarcinoma cell lines (A549 lung, MDA-MB231 and MCF7 breast, and the cisplatin resistant HCT116 colon). The results revealed a remarkable antiproliferative activity of the triphenylphosphane mononuclear compounds 3-4 (series a, b, c) and the best inhibition was provided for 3c and 4c with the 2-phenylaniline ligand and a six membered chelate ring. Interestingly, 3c and 4c were 14 and 19 times more potent than cisplatin for the inhibition of the cisplatin resistant HCT116 human adenocarcinoma cell line, respectively. Cyclopalladated complexes 3c and 4c exercise their antiproliferative activity over A549 cells mainly through the induction of apoptosis (38 and 31-fold increase in early apoptotic cells, respectively).

8-aryl-2-azabicyclo[3.3.1]nonan-7-ones. Synthesis and retro-michael ring opening

Abstract The synthesis of 8-aryl-2-azabicyclo[3.3.1]nonan-7-ones ( 7 ) by acid cyclization of 4-(3-aryl-2-oxopropyl)-2-piperidinecarbonitriles ( 5 ) is reported. Bicyclic α-aril-β-amino ketones 7 easily undergo a retro-Michael ring opening to give the corresponding 2-arylcyclohexenones 8 .

Cyclization of 1-(carbamoyl)dichloromethyl radicals upon activated alkenes. A new entry to 2-azabicyclo[3.3.1]nonanes

Abstract The synthesis of 2-azabicyclo[3.3.1]nonanes using a radical cyclization process as the piperidine ring-forming step is described. The reaction involves 1-(carbamoyl)-dichloromethyl radicals which react intramolecularly with simple or activated alkenes, such as enol acetates or silyl enol ethers.

Cyclopalladated and cycloplatinated benzophenone imines: Antitumor, antibacterial and antioxidant activities, DNA interaction and cathepsin B inhibition

The antitumor, antibacterial and antioxidant activity, DNA interaction and cathepsin B inhibition of cyclo-ortho-palladated and -platinated compounds [Pd(C,N)]2(μ-X)2 [X=OAc (1), X=Cl (2)] and trans-N,P-[M(C,N)X(PPh3)] [M=Pd, X=OAc (3), M=Pd, X=Cl (4), M=Pt, X=Cl (5)] are discussed [(C,N)=cyclo-ortho-metallated benzophenone imine]. The cytotoxicity of compound 5 has been evaluated towards human breast (MDA-MB-231 and MCF-7) and colon (HCT-116) cancer cell lines and that of compounds 1-4 towards the HCT-116 human colon cancer cell line. These cytotoxicities have been compared with those previously reported for compounds 1-4 towards MDA-MB-231 and MCF-7 cancer cell lines. Compound 3 and 4 were approximately four times more active than cisplatin against the MDA-MB-231 and MCF-7 cancer cell lines, and compound 5, was approximately four times more potent than cisplatin against the HCT-116 cancer cell line. The antibacterial activity of compounds 1-5 was in between the ranges of activity of the commercial antibiotic compounds cefixime and roxithromycin. Complexes 1-2 and 4-5 presented also antioxidant activity. Compounds 1-5 alter the DNA tertiary structure in a similar way to cisplatin, but at higher concentration, and do not present a high efficiency as cathepsin B inhibitors. Compound 5 has not been previously described, and its preparation, characterization, and X-ray crystal structure are reported.