Stable σ-adducts of 4,6-dinitrotetrazolo[1,5-a]pyridine with alkoxide anions

The reaction of 2-chloro-3,5-dinitropyridine with two equivalents of KN₃ in the presence of ROH results in stable Meisenheimer-type -adducts of 4,6-dinitrotetra-zolo[1,5-a]pyridine with RO^– anions (R = H, Alk, Ph). The mechanism of -complex formation was suggested. The structure of the -adduct with R = Me was established by IR and NMR spectroscopy and by X-ray diffraction analysis.For the preliminary communication, see Ref. 1.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1278–1283, July, 1994.This work was supported by the Russian Foundation for Basic Research (project code 93-03-5329).     

Luminescent PtII and PtIV Platinacycles with Anticancer Activity Against Multiplatinum-Resistant Metastatic CRC and CRPC Cell Models

Platinum-based chemotherapy persists to be the only effective therapeutic option against a wide variety of tumours. Nevertheless, the acquisition of platinum resistance is utterly common, ultimately cornering conventional platinum drugs to only palliative in many patients. Thus, encountering alternatives that are both effective and non-cross-resistant is urgent. In this work, we report the synthesis, reduction studies, and luminescent properties of a series of cyclometallated (C,N,N′)Pt^IV compounds derived from amine–imine ligands, and their remarkable efficacy at the high nanomolar range and complete lack of cross-resistance, as an intrinsic property of the platinacycle, against multiplatinum-resistant colorectal cancer (CRC) and castration-resistant prostate cancer (CRPC) metastatic cell lines generated for this work. We have also determined that the compounds are effective and selective for a broader cancer panel, including breast and lung cancer. Additionally, selected compounds have been further evaluated, finding a shift in their antiproliferative mechanism towards more cytotoxic and less cytostatic than cisplatin against cancer cells, being also able to oxidize cysteine residues and inhibit topoisomerase II, thereby holding great promise as future improved alternatives to conventional platinum drugs.     

From Bowls to Capsules: Assembly of Hexanuclear NiII Rings Tailored by Alkali Cations

An anionic hexanuclear Ni^II metallamacrocycle with endo and exo linking sites has been employed as a building block to generate a series of capsules and bowls of nanometric size. The supramolecular arrangement of the {Ni₆} rings was tailored by the size of the alkali cations, showing the transition from {Ni₆-M₂-Ni₆} capsules (M=Li^I and Na^I) to {Ni₆-M} bowls (M=K^I and Cs^I). The alkyl co-cations are determinant to stabilize the assemblies by means of CH⋅⋅⋅π interactions on the exo side of the metallamacrocycles. The effect on the topology of the supramolecular assemblies of the cation size, cation charge, Et₃NH⁺ or Me₄N⁺ counter cations has been analyzed. Magnetic measurements reveal the presence of ferromagnetic and antiferromagnetic interactions inside the rings that allow a S=0 ground state.     

Alternative syntheses of the D2d symmetric 1,3,5,7-tetraiodotricyclo[3.3.0.0]octane

Three alternative syntheses of 1,3,5,7-tetraiodotricyclo[3.3.0.0^3,7]octane are described. Reaction of this tetraiodide with sodium amalgam in the presence of dienes or with molten sodium in boiling 1,4-dioxane in the absence of trapping agents led to very complex mixtures of products, presumably due to competitive 1,2- and 1,3-deiodination reactions.     

Reaction of 2-amino-4-imino-2-perfluoropentene with ethylenediamine and diethylenetriamine

The transamination of 2-amino-4-imino-2-perfluoropentene with ethylenediamine gives the corresponding 6-fluoro-5,7-bis(trifluoromethyl)-2,3-dihydro-1H-1,4-diazepine. The transamination of 2-amino-4-imino-2-perfluoropentene by diethylenetriamine is accompanied by intramolecular nucleophilic substitution of the α-fluorine atom to form 1,9-bis(trifluoromethyl)-3,4,6,7-tetrahydro-2H-pyrazino[1,2-a]pyrazine whose structure was established by an X-ray structural investigation. Several salts of this bicyclic compound and its complex with BF₃ have been described. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1773–1776, October, 1993.     

Diastereoselective preparation of (S)-(1,4,4-trimethylpyrrolidin-3-yl)amine, a new chiral 1,2-diamine for thiourea-type organocatalysts

The enantioselective synthesis of the title compound, its conversion into a thiourea-type organocatalyst and the behavior of this organocatalyst in several enantioselective Michael reactions are described.