Search results for "medicina."

Deprotonation of Benzoxazole and Oxazole Using Lithium Magnesates

2005

International audience; The first deprotonations of oxazole and benzoxazole using lithium magnesates are described. The reactions occurred in tetrahydrofuran at room temperature using 1/3 equiv of lithium tributylmagnesate. As 2-lithiooxazole and 2-lithiobenzoxazole, lithium tri(2-oxazolyl)magnesate and lithium tri(2-benzoxazolyl)magnesate very rapidly and completely isomerized to the more stable 2-(isocyano)enolate and 2-(isocyano)phenolate type structures, respectively, a result shown by NMR analysis. The isolation of 2-substituted oxazoles and benzoxazoles in medium to good yields after electrophilic trapping was interpreted in two ways:  (1) the equilibration between the open and closed…

A Selenium-Nitrogen Chain with Selenium in Different Oxidation States

2017

Alkali Blues: Blue‐Emissive Alkali Metal Pyrrolates

2019

2-Iminopyrroles [HtBu L, 4-tert-butyl phenyl(pyrrol-2-ylmethylene)amine] are non-fluorescent π systems. However, they display blue fluorescence after deprotonation with alkali metal bases in the solid state and in solution at room temperature. In the solid state, the alkali metal 2-imino pyrrolates, M(tBu L), aggregate to dimers, [M(tBu L)(NCR)]2 (M=Li, R=CH3 , CH(CH3 )CNH2 ), or polymers, [M(tBu L)]n (M=Na, K). In solution (solv=CH3 CN, DMSO, THF, and toluene), solvated, uncharged monomeric species M(tBu L)(solv)m with N,N'-chelated alkali metal ions are present. Due to the electron-rich pyrrolate and the electron-poor arylimino moiety, the M(tBu L) chromophore possesses a low-energy intra…

Synthesis, crystal structure, DFT and biological activity of E-pyrene-1-carbaldehyde oxime and E-2-naphthaldehyde oxime

2020

Abstract The aldoximes E-pyrene-1-carbaldehyde oxime 1 and E-2-naphthaldehyde oxime 2 were synthesized, in ca. 90% yield, by treatment of pyrene-1-carbaldehyde or 2-naphthaldehyde, respectively, with hydroxylamine hydrochloride and sodium carbonate in MeOH. Compounds 1 and 2 were characterized by IR, 1H and 13C{1H} NMR spectroscopies, elemental analyses and single crystal X-ray diffraction (in the case of 1). The studied system (compound 1) showed significant amounts of H⋯H (44.4%), C⋯H (25.4%) and C⋯C (13.3%) intermolecular interactions in addition to the short N⋯H (5.9%) and O⋯H (6.2%) intermolecular interactions. These interactions affect the molecular packing of the studied system in th…

A new polyketide from the bark of Hypericum roeperianum Schimp. (Hypericaceae)

2019

The isolation and spectroscopic data of a hitherto undescribed polyketide (1) from Hypericum roeperianum Schimp. (Hypericaceae) together with six known compounds (2–7) is herein reported. The struc...

Cis versus Trans: The Coordination Environment about the Tin(IV) Atom in Spirocyclic Amino Alcohol Derivatives.

2018

The syntheses of amino alcohols MeN(CH2 CH2 CMe2 OH)2 (1), MeN(CMe2 CH2 OH)(CH2 CMe2 OH) (2), MeN(CH2 CH2 CH2 OH)(CH2 CMe2 OH) (3), MeN(CH2 CH2 CMe2 OH)(CH2 CMe2 OH) (4), MeN(CH2 CH2 CMe2 OH)(CH2 CH2 OH) (5), and MeN(CH2 CH2 OH) (CH2 CH2 CH2 OH) (6) as well as spirocyclic tin(IV) alkoxides spiro-[nBuN(CH2 CMe2 O)2 ]2 Sn (7), spiro-[MeN(CH2 CH2 CMe2 O)2 ]2 Sn (8), spiro-[para-FC6 H4 N (CH2 CMe2 O)2 ]2 Sn (9), spiro-[MeN(CMe2 CH2 O)(CH2 CMe2 O)]2 Sn (10), spiro-[MeN(CH2 CH2 CH2 O)(CH2 CMe2 O)]2 Sn (11), spiro-[MeN(CH2 CH2 CMe2 O)(CH2 CMe2 O)]2 Sn (12), spiro-[MeN(CH2 CH2 CMe2 O)(CH2 CH2 O)]2 Sn (13) and spiro-[MeN(CH2 CH2 O)(CH2 CH2 CH2 O)]2 Sn (14) are reported. The compounds were characteri…

Amino‐Substituted Ferra‐bis(tricarbollides) − Metallatricarbaboranes Designed for Linear Molecular Constructions

2004

Reactions between high purity FeCl2 and the anion [nido-7-(tBuHN)-7,8,9-C3B8H10)]− (1−) have been used for efficient syntheses of the twelve-vertex double-cluster metallatricarbollide complexes of the para,para (p,p) type [closo-9,9′(RHN)2-commo-2,2′-FeII-1,7,9-(C3B8H10)-1′,7′,9′-(C3B8H10)] (2) (2a, R = tBu and 2b, R = H) (yields 42−45% for 2a). Compound 2b, which contains two reactive amino substituents conveniently attached to the tricarbollide subclusters in p-positions with respect to the metal center, was prepared via facile cleavage of the tBu substituent in 2a either by AlCl3 or by thermal means. The structure of 2b constitutes a good setting for the synthesis of building blocks for …

Influence of the solvent and R groups on the structure of (carboranyl)R2PI2 compounds in solution. Crystal structure of the first iodophosphonium sal…

2008

The influence of the electron-donor or electron-acceptor capacity of the R groups (R = (i)Pr, Ph, Et) and the solvent on the molecular geometry in solution of adducts of carboranylphosphanes [(carboranyl)(i)Pr2P, (carboranyl)Ph2P and (carboranyl)Et2P] with I2 in 1 : 1 ratios, has been studied in detail by 31P{1H} and 11B{1H} NMR spectroscopies. The more electron-accepting Ph groups make the (carboranyl)Ph2P less nucleophilic, thus stabilizing the I2 encapsulated neutral biscarboranylphosphane-diiodine adducts in solution, such as (carboranyl)Ph2PI-IPPh2(carboranyl), generating P---I-I---P motifs. Even in a polar solvent, such as EtOH, the arrangement is preserved. The expected basicity of t…

The [Pd(bipy)]2+ “merry-go-round”: Insights into the lability of the Pd–N bond

2009

Abstract Two tripods (1 and 2) featuring pyrimidinyl pendant arms have been synthesized from 5-(1H-pyrazol-3-yl)-pyrimidine (5) and 1,3,5-tribromomethylbenzene derivatives. Reaction with three equivalents of [Pd(bipy)](NO3)2 to form a macrotricycle closed by palladium coordination unexpectedly afforded the mononuclear species [Pd(1)(bipy)]2+ and [Pd(2)(bipy)]2+. These complexes show fluxional behavior on the 1H NMR timescale, the [Pd(bipy)]2+ fragment hopping between the pyrimidinyl coordinating moieties. The ΔGc‡’s estimated by the coalescence method are temperature independent, which means that ΔSc‡ = 0. This indicates that the “merry-go-round” process of [Pd(bipy)]2+ occurs intramolecula…

Asymmetric Vinylogous Mannich-Type Addition of α,α-Dicyanoalkenes to α-Fluoroalkyl Sulfinyl Imines

2018

Abstract. The asymmetric vinylogous Mannich reaction (AVMR) of alfa,alfa-dicyanoalkenes with alfa-fluoroalkyl sulfinyl imines has been successfully accomplished. This transformation is unprecedented with fluorinated imines at the same time as the use of dicyanoalkenes in AVMR has been scarcely reported. Several fluorinated sulfinyl imines are compatible with the process, which gaves access to a family of chiral fluorinated amines with excellent level of stereocontrol. Interestingly, the selectivity found in our protocol is reverse to that encountered in analogous AVMR previously reported. Additionally, the synthetic applicability of the addition products has been exemplified with several tr…