3-[2-(Aminocarbonyl)pyridinium-1-yl]propane-1-sulfonate, a promising medicinal betain, was prepared by a one-pot synthesis with a 89% yield via N-alkylation of ethyl picolinate with 1,3-propanesultone in MeCN followed by ammonolysis. The reaction involving picolinamide in MeOH followed by the treatment with acetone afforded a novel 3,3-dimethyl- 1-oxo-2,3-dihydro-1H-imidazo[1,5-a]pyridin-4-ium 3-methoxypropane-1-sulfonate.

A series of anionic phenylsilicon(IV) bis-catecholate complexes, where (Cat1)– = catecholate, (Cat2)– = 3,4,5,6-tetrabromocatecholate, (Cat3)– = 4-cyanocatecholate, (Cat4)– = 4-nitrocatecholate, (Cat5)– = 3-fluorocatecholate, and (Cat6)– = 4,5-dibromocatecholate, were prepared by the reaction of trimethoxyphenylsilane with two equivalents of catechol or its derivatives containing electron-withdrawing substituents in the benzene ring in the presence of dicyclohexylamine. The complexes were characterized by IR spectra and 1H, 13C, and 29Si NMR spectra, voltammetry, and ESR. The heteroligand anionic phenylsilicon(IV) complexes crystallized from solutions as salts (Chex2NH2)[PhSi(Cat1)2] (I), (Chex2NH2)-[PhSi(Cat2)2]·0.5C6H14 (II), (Chex2NH2)[PhSi(Cat3)2]·2C6H6 (III), (Chex2NH2)[PhSi(Cat4)2]· H2O (IV), (Chex2NH2)[PhSi(Cat5)2] (V), and (Chex2NH2)[PhSi(Cat6)2] (VI) (Chex2 $${\text{NH}}_{2}^{ + }$$ = dicyclohexylammonium). The composition and structure of the products were confirmed by X-ray diffraction data (CCDC nos. 2150293–2150297 for I–V, respectively). The effect of substituent in the benzene ring on the electronic structure of the anion was studied by PBE0/6-311G(d,p) quantum chemical calculations with allowance for non-specific solvation (PCM model). The oxidation potentials of II–VI were measured; radical formation upon electrochemical oxidation and reduction was observed for II.

A virtual set of new lactam-containing derivatives of arylsulfonylglycines 1a–d and 2a–d was designed and analyzed using structure–activity computer models (web-services PASS Online, AntiBac-Pred, and GUSAR Acutetoxicity). The antimicrobial activity against Staphylococcus aureus along with low toxicity was predicted for these derivatives. Compounds 1a–d and 2a–d were synthesized by the reactions of N-trimethylsilyl lactams with 4-substituted [(phenyl)sulfonyl]aminoacetyl chlorides. The structures of new compounds were confirmed by IR spectroscopy, NMR spectroscopy, and elemental analysis data. According to the results of studies in vitro, compounds 1a–d and 2a–d efficiently suppress the growth of S. aureus. Lactam-containing benzenesulfonamides bearing the bromine atom or methyl or nitro group at position 4 manifested the most pronounced activity.

Halogen exchange reactions between hexacoordinate tin dihalides (LnCH2)2SnX2 and (LnCH2)2SnY2 (LnCH2 = C,O-chelate n-membered lactamomethyl ligand, n = 5–7, X, Y = Cl, Br, I) produce mixed dihalides (LnCH2)2SnXY. Along with the signals of original complexes, NMR 119Sn spectra of solutions containing two different homodihalides show the third signal with a median chemical shift. The results of NMR monitoring studies, conductivity data and quantum-chemical calculations suggest that mixed dihalides readily form in solutions, although these complexes have not been isolated as individual compounds.

The reaction of N -trimethylsilyl derivatives of amides and imides with alkyl sulfonates on heating affords the corresponding N -alkyl derivatives and trimethylsilyl sulfonates.

Reactions of (O -> Ge)-bischelate dibromogermane ((LCH2)-C-7)(2)GeBr2 (4c) with trimethyliodosilane and trimethylsilyl triflate proceed with the substitution of only one bromine atom and yield (O -> Ge)-bischelate monobromogermanes ((LCH2)-C-7)(2)Ge(Br)X (8c, X = I; 9c, X = OTf; (LCH2)-C-n = lactamomethyl C,O-chelate ligand; n = lactam ring size). According to X-ray crystal analysis data, triflate 9c is characterized by nearly ionic structure with the monodentate ligand and anion in trans-positions. The configuration of the germanium atom in the complex is intermediate between trigonal bipyramidal and square pyramidal. Quantum chemical calculations show the absence of additional coordinate bonding between the germanium atom and anion. Dynamic H-1 NMR spectroscopy (H-1 DNMR) was used to study the stereochemical non-rigidity of monobromides 8c and 9c. Activation parameters for the inversion of the germanium atom configuration were calculated in various solvents. Based on the H-1 DNMR data and quantum chemistry calculations, possible mechanisms of permutational isomerization are discussed. (C) 2020 Elsevier B.V. All rights reserved.

Derivatives of the amino acids sarcosine and proline – triflates TsN(Me)CH2C(O)N(Me)-CH2SiMe2OTf and Ns–Pro–N(Me)CH2SiMe2OTf (Ns is 4-NO2C6H4SO2) – were synthesized by the reaction of trimethylsilyl triflate with halosilanes prepared previously. Bromide NsNHCH(Me)C(O)N(Me)CH2SiMe2Br was synthesized by the cleavage of the Si–O–Si moiety of the appropriate disiloxane with excess acetyl bromide. The X-ray diffraction study of these compounds and of the previously characterized bromide TsN(Ac)CH2C(O)N(Me) CH2SiMe2Br showed that the Si–O coordination bond lengths in the triflates are 1.7692(14)– 1.8623(14) Å. The interatomic distances between the bromine and silicon atoms are 2.7095(8) and 2.9704(7) Å, which indicates that these bonds are weak. To elucidate the nature of Si…X bonding (X = OTf, Br), the topological analysis of electron density was performed and 29Si NMR chemical shifts were calculated. The interatomic Si…X interaction in triflate TsN(Me)CH2C(O)- N(Me)CH2SiMe2OTf and bromide TsN(Ac)CH2C(O)N(Me)CH2SiMe2Br is weak. In triflate Ns–Pro–N(Me)CH2SiMe2OTf and bromide NsNHCH(Me)C(O)N(Me) CH2 SiMe2Br, the Si…X interaction is significantly stronger and corresponds to a weak coordination bond. Hence, the tosylates can be considered as salts, whereas the para-nitrobenzenesulfonyl derivatives are monochelated five-coordinate silicon complexes.

Anionic five-coordinate complexes with two bis-O,O’-chelating ligands bearing α-hydroxy acid moieties, dicyclohexylammonium salts $$\text{Cy}_{2}\text{NH}_{2}{^+}\{\text{PpnCH}_2\text{Si}[\text{OCR}_2\text{C}\text{(O)O]}_2\}^-$$ (Cy is cyclohexyl, PpnCH2 is 4-methyl-2,5-dioxopiperazin-1-ylmethyl, R = Me, Ph), were synthesized by esterification of alkoxysilane PpnCH2Si(OMe)3 with α-hydroxy acids (dimethyl- and diphenylgylcolic acids) in the presence of dicyclohexylamine. The five-coordinated state of the silicon atom in the resulting compounds in solution was confirmed by 29Si NMR spectroscopy. According to the X-ray diffraction data, the synthesized compounds contain the SiCO4 coordination unit.

The structures and stereodynamic behavior of (O -> Si)-chelate methyldifluorosilanes in solutions were studied by multinuclear (H-1, C-13, F-19, Si-29) and 2D (COSY, HETCOR H-1, C-13) NMR spectroscopy. The range of studied complexes included amides RC(O)N(R')CH2SiMeF2 [R = Ph, R' = H (1a); R = R' = Me (1b); R = Me, R' = CHMePh (1c)], lactams LCH2SiMeF2 (L = 2-oxoazepan-1-yl (2a), 2,2-dimethyl-4-oxo-2H-benzo[1,3] oxazin-3-yl (2b) or 4-methyl-2-oxoquinolin-l-yl (2c)] and the six-membered imide Im(6)CH(2) [2,6-dioxopiperidin-1-yl (3)]. The pentacoordination of silicon atoms in all studied compounds was confirmed by NMR study in solutions and single-crystal X-ray studies of complexes 1c, 2a, 2c and 3. The temperature dependency observed for the F-19 NMR signals in solution was explained by the ligand exchange in the coordination environment of silicon atoms (permutational isomerization) and used for determining the activation parameters of this process by F-19 DNMR. Quantum-chemical calculations for various isomers of complexes 1c, 2a, 2c and 3 suggested the "turnstile rotation" as the most likely mechanism for the observed stereodynamic processes. (C) 2018 Elsevier B.V. All rights reserved.

A series of mono-, bis-, and tris-substituted lactamomethyl derivatives of diphenols were synthesized. The solution and solid-state structures of these compounds were confirmed by IR and NMR spectroscopy and X-ray diffraction. The in silico evaluation indicated a high probability that these compounds have various biological activities.

Silylmethylation of N-acetylvaline with the ClCH2SiMe2Cl(Me3Si)(2)NH system gave the previously unknown 2-silamorpholin-6-one derivative, whose hydrolysis in aqueous ethanol produced bis-acetylvaline-containing disiloxane. The X-ray diffraction study and quantum chemical calculations demonstrated that both silicon atoms in the final product are four-coordinated.

Pentacoordinated monofluorosilanes R1SO2NHCHR2C(O)N(Me)CH2SiMe2F containing moieties of N′-methyl-N-(organosulfonyl)-2-amino acid amides of glycine, alanine, and leucine as C,O-chelating ligands were synthesized via the reaction of corresponding disiloxanes with BF3•Et2O. The structures of obtained compounds were investigated by single-crystal X-ray diffraction analysis.

A reaction of bicyclic 2-sila-5-piperazinone, 2,2,4-trimethyl-1,4-diaza-2-silabicyclo-[4.3.0]nonan-5-one containing a proline moiety, and N-tosylglycine acyl chloride with subsequent hydrolysis of the primary unstable product to the intermediate disiloxane and its treatment with BF3•OEt2 furnished a first representative of pentacoordinate C,O-chelate halosilanes with a dipeptide fragment, namely, Ts—Gly—(S)-Pro—N(Me)CH2SiMe2F.

Bis(chelate) dichlorogermane (L8CH2)2GeCl2 (1) with the monoanionic lactamomethyl (С,О)-chelate ligand based on enantolactam (L8H) was synthesized, and its molecular and crystal structures were studied. The germanium atom is characterized by the octahedral configuration with the mutual cis-arrangement of the Cl and O atoms and trans-arrangement of the C atoms. The scheme of transformation of dichlorogermane 1 into the bis(chelate) cationic complex (L8CH2)2Ge(Cl)OTf (2) was proposed. The H-bonded complexes of dichlorogermane 1 with HOSO2CF3 and HCl assumed to be intermediates in this process were studied by quantum chemical calculation. The energy necessary for the dissociation of the H-bonded complexes to the germylium cation and HCl2 – and СlHOSO2CF3 – anions depends on the relative arrangement of the Cl atoms in the coordination polyhedron of the Ge atom. In the case of the cis-arrangement of the Cl atoms in the H-bonded complexes, the dissociation energy was estimated as 11.5—16.1 kcal mol–1.

Bis[(2,2-dimethyl-4-oxo-2 H -benzo[ e ][1,3]oxazin-3(4 H )-yl)methyl]dichlorosilane ( 1 ) and -germane ( 2 ) were synthesized by the reaction of 2,2-dimethyl-3-(trimethylsilyl)-2 H -benzo[e][1,3]oxazin-3(4 H )-one with bis(chloromethyl)dichlorosilane and -germane, respectively, taken in a ratio of 2 : 1. The structures of these compounds were determined and their stereodynamic behavior in solution was studied by multinuclear ( 1 H, 13 C, and 29 Si) and twodimensional ( 1 H, 13 C COSY, HETCOR) NMR spectroscopy. The 29 Si NMR spectroscopic study of a solution of complex 1 provides evidence that the silicon atom in this complex is pentacoordinate. The X-ray diffraction study showed that the germanium atom in complex 2 in the solid state is hexacoordinate. The permutation isomerization in the coordination units of complexes 1 and 2 was found and investigated by dynamic 1 H NMR spectroscopy. Different mechanisms of stereodynamic transformations are suggested and discussed.

NMR spectroscopy was used to study a series of C,O-monochelate N ′-(fluorodimethyl-silylmethyl)- N ′-methyl- N -(organosulfonyl)proline amides in the solid state and in solutions in chloroform, pyridine, and acetone. The structure of one of the complexes was established by X-ray crystallography. Quantum chemical calculations were performed to interpret the spectral data obtained. The molecular conformation observed in crystal was found to be retained in solutions. The coordination bonds of silicon atom with acetone and pyridine are very weak and cannot stabilize the acyclic form (without the Si-O coordination bond). The 29 Si chemical shift was found to be directly dependent on the Si-O bond distance. The mutual influence of organosulfonyl group and chelate ring was described in terms of polarization effects.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

The reaction of amides RSO2-Pro-NHMe with ClCH2SiMe2Cl in the presence of (Me3Si)2NH gave pentacoordinated chlorosilanes RSO2-Pro-N(Me)CH2SiMe2Cl with an organosulfonyl group (R = Me, Ph, 4-ClC6H4, 4-BrC6H4, 4-MeC6H4, and 4-O2NC6H4) attached to the proline nitrogen atom. An alternative method for the preparation of these compounds comprises the cyclosilylmethylation of proline methylamide by dimethylchloromethylchlorosilane to give the previously unreported heterocyclic 2-sila-5-piperazinone system in the first step. The bicyclic silacyclane synthesized is 2-sila5-piperazinone condensed with a proline residue. The action of sulfonyl chlorides RSO2Cl leads to cleavage of the sila ring Si–N bond to give the desired chlorosilanes. The hydrolysis of these products, depending on the reaction conditions, gives either silyloxonium chlorides [RSO2-ProN(Me)CH2SiMe2OH2]Cl or disiloxanes [RSO2-Pro-N(Me)CH2SiMe2]2O. X-ray diffraction structural analysis showed that the silicon atom in the chlorides and silyloxonium chlorides is pentacoordinated due to an intramolecular O → Si bond and has distorted trigonal-bipyrimidal configuration. 29Si NMR spectroscopy showed that the disiloxanes and bicyclic sila-5-piperazinone have a tetracoordinated silicon atom.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.