The synthesis of tetrafluorinated aminosugars

The synthesis of two tetrafluorinated 4-aminosugars, 4-amino-2,3,4-trideoxy-2,2,3,3-tetrafluoro-d-erythro-hexopyranose hydrochloride (7•HCl) and 4-amino-2,3,4-trideoxy-2,2,3,3-tetrafluoro-d-threo-hexopyranose hydrochloride (8•HCl), is described. The amino group in ?-position of a CF2(CF2) group is proposed as a mimic for the hydrogen bond accepting capacity of an alcohol group in an unfluorinated sugar. The synthesis of the two sugars was achieved in 4 steps each from the sulfinylimine diastereoisomers of d-glyceraldehyde

Sequential Migrations between Boron and Rhodium Centres: A Cooperative Process between Rhodium and a Mono-Substituted Borohydride Unit

The sodium salt of a monosubstituted borohydride anion containing a 2-mercaptopyridyl unit (mp) is reported herein. This compound was coordinated to a rhodium(I) center providing the complex [Rh{κ3-H,H,S–H3B(mp)}(NBD)] (1) (where NBD = 2,5-norbornadiene) in which the boron-based ligand is coordinated to the rhodium center via the thione donor and two of the B–H bonds of the BH3 unit. Reaction of complex 1 with carbon monoxide results in the activation of the complex leading to the product of a formal intramolecular hydroboration reaction, where the NBD unit has, in effect, inserted into one of the B–H bonds. Three complexes were prepared in which the newly formed norbornenyl unit (nbe) is located at the boron center, namely, [Rh{κ3-H,H,S–H2B(nbe)(mp)}(CO)2] (2), [Rh{κ3-H,H,S–H2B(nbe)(mp)}(CO)(PCy3)] (3), and [Rh{κ3-H,H,S–H2B(nbe)(mp)}(CO)(PPh3)] (4). The identities of the three complexes were confirmed by spectroscopic and analytical techniques. Further confirmation was obtained via structural characterization of 3. Studies confirmed that the reactivity occurs at the metal center. A metal–ligand cooperative mechanism, involving initial migration of hydride from boron to metal center, was postulated for the formation of the new complexes based on previous investigations. The newly formed norbornenyl unit then migrates from metal center to boron

Fe III in a low-spin state in caesium bis[3-ethoxysalicylaldehyde 4-methylthiosemicarbazonato(2–)-κ3O2,N1,S]ferrate(III) methanol monosolvate

The synthesis and crystal structure (at 100K) of the title compound, Cs[Fe(C11H13N3O2S2) 2] CH3OH, is reported. The asymmetric unit consists of an octahedral [FeIII(L)2]- fragment, where L 2- is 3-ethoxysalicylaldehyde 4-methylthiosemicarbazonate(2-) {systematic name: [2-(3-ethoxy-2-oxidobenzylidene)hydrazin-1-ylidene] (methylamino)methanethiolate}, a caesium cation and a methanol solvent molecule. Each L2- ligand binds through the thiolate S, the imine N and the phenolate O atoms as donors, resulting in an FeIIIS2N 2O2 chromophore. The O,N,S-coordinating ligands are orientated in two perpendicular planes, with the O and S atoms in cis positions and the N atoms in trans positions. The FeIII cation is in the low-spin state at 100K

Massachusetts model system for educator evaluation

The synthesis and characterization of a series of platinum and palladium complexes containing a secondary borane Z-class ligand supported by 2-mercaptopyridine heterocycles is reported herein. Addition of 2 equiv of Na[H2B(mp)2] to [Pt(μ-Cl)(COEOMe)]2 (where COEOMe = 8-methoxycyclooct-4-en-1-ide) in the presence of 2 equiv of a tertiary phosphine (PR3 = PPh3, PCy3, PCyp3, P(o-tol)3, PPh2(o-tol), PPh2(2-(3-methyl)indolyl)) leads to the formation of the complexes [Pt{κ3-S,B,S-HB(mp)2}(PR3)] (1–6). Addition of 2 equiv of Na[H2B(mp)2] to [Pd(μ-Cl)(COEOMe)]2 in the presence of 2 equiv of a tertiary phosphine (PR3 = PPh3, PCy3, PCyp3, PPh2(o-tol)) leads to the formation of the complexes [Pd{κ3-S,B,S-HB(mp)2}(PR3)] (7–10). It was also demonstrated that the synthesis of the palladium complex 7 could be achieved from the palladium precursor [PdCl(Me)(COD)] (where COD = 1,5-cyclooctadiene) as an alternative synthetic strategy. In the above reactions, either the COEOMe fragment or the methyl fragment serves to act as a “hydride acceptor” facilitating the ultimate transformation of the borohydride-based ligand [H2B(mp)2]− to the corresponding secondary borane κ3-S,B,S coordinated HB(mp)2 pincer ligand. The complexes [Pd{κ3-S,B,S-HB(mp)2}(PR3)] and [Pt{κ3-S,B,S-HB(mp)2}(PR3)] are rare examples of metal–borane complexes where one hydrogen substituent remains at the boron center. These compounds have particularly short palladium– and platinum–boron distances, the shortest of the structurally characterized compounds being 2.067(6) Å for [Pd{κ3-S,B,S-HB(mp)2}(PPh2(o-tol))] and 2.076(10) Å for [Pt{κ3-S,B,S-HB(mp)2}(PCy3)], respectively (the shorter distances of two independent complexes in the unit cells of both structures)

Synergistic effects of inhibiting the MNK-eIF4E and PI3K/AKT/mTOR pathways on cell migration in MDA-MB-231 cells

The study of eukaryotic initiation factor 4E (eIF4E) is a key focus in cancer research due to its role in controlling the translation of tumour-associated proteins, that drive an aggressive migratory phenotype. eIF4E is a limiting component of the eIF4F complex which is a critical determinant for the translation of mRNAs. Mitogenactivated protein kinase interacting protein kinases (MNK1/2) phosphorylate eIF4E on Ser209, promoting the expression of oncogenic proteins, whereas mTORC1 phosphorylates and de-activates the eIF4E inhibitor, 4E-BP1, to release translational repression. Here we show that inhibiting these pathways simultaneously effectively slows the rate of cell migration in breast cancer cells. However, a molecular hybridisation approach using novel, cleavable dual MNK1/2 and PI3K/mTOR inhibiting hybrid agents was less effective at slowing cell migration

Caesium bis­(5-bromo­salicyl­aldehyde thio­semicarbazonato-κ3O,N,S)ferrate(III): supramolecular arrangement of low-spin FeIII complex anions mediated by Cs+ cations

The synthesis and crystal structure determination (at 293 K) of the title complex, Cs[Fe(C8H6BrN3OS)2], are reported. The compound is composed of two dianionic O,N,S-tridentate 5-bromo­salicyl­aldehyde thio­semicarbazonate(2-) ligands coord­inated to an FeIII cation, displaying a distorted octa­hedral geometry. The ligands are orientated in two perpendicular planes, with the O- and S-donor atoms in cis positions and the N-donor atoms in trans positions. The complex displays inter­molecular N-H...O and N-H...Br hydrogen bonds, creating R44(18) rings, which link the FeIII units in the a and b directions. The FeIII cation is in the low-spin state at 293 K

Adding to the Family of Copper Complexes Featuring Borohydride Ligands Based on 2-Mercaptopyridyl Units

Borohydride ligands featuring multiple pendant donor functionalities have been prevalent in the chemical literature for many decades now. More recent times has seen their development into new families of so-called soft scorpionates, for example, those featuring sulfur based donors. Despite all of these developments, those ligands containing just one pendant group are rare. This article explores one ligand family based on the 2-mercaptopyridine heterocycle. The coordination chemistry of the monosubstituted ligand, [H3B(mp)]− (mp = 2-mercaptopyridyl), has been explored. Reaction of Na[BH3(mp)] with one equivalent of Cu(I)Cl in the presence of either triphenylphosphine or tricyclohexylphosphine co-ligands leads to the formation of [Cu{H3B(mp)}(PR3)] (R = Ph, 1; Cy, 2), respectively. Structural characterization confirms a κ3-S,H,H coordination mode for the borohydride-based ligand within 1 and 2, involving a dihydroborate bridging interaction (BH2Cu) with the copper centers

N1-arylation of 1,4-benzodiazepine-2-ones with diaryliodonium salts

A library of N1-arylated 5-phenyl-1,3-dihydro-2H-1,4-benzodiazepin-2-ones has been synthesized starting with unsymmetrical diaryliodonium salts using aqueous ammonia as a base. This can also be applied to a similar 1,3,4-benzotriazepin-2-one derivative

Frustrated Lewis pair (FLP)-catalyzed hydrogenation of aza-Morita–Baylis–Hillman adducts and sequential organo-FLP catalysis

Herein we report the metal-free diastereoselective frustrated Lewis pair (FLP)-catalyzed hydrogenation of aza-Morita–Baylis–Hillman (aza-MBH) adducts, accessing a diverse range of stereodefined β-amino acid derivatives in excellent isolated yields (28 examples, 89% average yield, up to 90:10 d.r.). Furthermore, sequential organo-FLP catalysis has been developed. An initial organocatalyzed aza-MBH reaction followed by in situ FLP formation and hydrogenation of the electron-deficient α,β-unsaturated carbonyl compounds can be performed in one-pot, using DABCO as the Lewis base in both catalytic steps