Structural elaboration of the surprising ortho-zincation of benzyl methyl ether

Breaking with convention, the reaction of the sodium zincate, [(TMEDA)Na(μ-TMP)(μ-tBu)Zn(tBu)] with benzyl methyl ether (PhCH2OMe) produces exclusively an ortho-zincated intermediate [(TMEDA)Na(μ-TMP)(μ-C6H4CH2OMe)Zn(tBu)] instead of the expected 'thermodynamic' α-metallated product

Pre-inverse-crowns : synthetic, structural and reactivity studies of alkali metal magnesiates primed for inverse crown formation

Two new alkali metal monoalkyl-bisamido magnesiates, the potassium compound [KMg(TMP)2nBu] and its sodium congener [NaMg(TMP) 2nBu] have been synthesised in crystalline form (TMP = 2,2,6,6-tetramethylpiperidide). Devoid of solvating ligands and possessing excellent solubility in hydrocarbon solvents, these compounds open up a new gateway for the synthesis of inverse crowns. X-ray crystallography established that [KMg(TMP)2nBu] exists in three polymorphic forms, namely a helical polymer with an infinite KNMgN chain, a hexamer with a 24-atom (KNMgN)6 ring having endo-disposed alkyl substituents, and a tetramer with a 16-atom (KNMgN)4 ring also having endo-disposed alkyl substituents. Proving their validity as pre-inverse-crowns, both magnesiates react with benzene and toluene to generate known inverse crowns in syntheses much improved from the original, supporting the idea that the metallations take place via a template effect. [KMg(TMP)2nBu] reacts with naphthalene to generate the new inverse crown [KMg(TMP)2(2-C 10H7)]6, the molecular structure of which shows a 24-atom (KNMgN)6 host ring with six naphthalene guest anions regioselectively magnesiated at the 2-position. An alternative unprecedented 1,4-dimagnesiation of naphthalene was accomplished via [NaMg(TMP) 2nBu] and its NaTMP co-complex "[NaMg(TMP) 2nBu]·NaTMP", manifested in [{Na 4Mg2(TMP)4(2,2,6-trimethyl-1,2,3,4- tetrahydropyridide)2}(1,4-C10H6)]. Adding to its novelty, this 12-atom (NaNNaNMgN)2 inverse crown structure contains two demethylated TMP ligands as well as four intact ones. Reactivity studies show that the naphthalen-ide and -di-ide inverse crowns can be regioselectively iodinated to 2-iodo and 1,4-diiodonaphthalene respectively

Structural diversity in alkali metal and alkali metal magnesiate chemistry of the bulky 2,6-diisopropyl-N-(trimethylsilyl)anilino ligand

Bulky amido ligands are precious in s-block chemistry since they can implant complementary strong basic and weak nucleophilic properties within compounds. Recent work has shown the pivotal importance of the base structure with enhancement of basicity and extraordinary regioselectivities possible for cyclic alkali metal magnesiates containing mixed n-butyl/amido ligand sets. This work advances alkali metal and alkali metal magnesiate chemistry of the bulky aryl-silyl amido ligand [N(SiMe3)(Dipp)] (Dipp = 2,6-iPr2-C6H3). Infinite chain structures of the parent sodium and potassium amides are disclosed, adding to the few known crystallographically characterised unsolvated s-block metal amides. Solvation by PMDETA or TMEDA gives molecular variants of the lithium and sodium amides; whereas for potassium, PMDETA gives a molecular structure but TMEDA affords a novel, hemi-solvated infinite chain. Crystal structures of the first magnesiate examples of this amide in [MMg{N(SiMe3)(Dipp)}2(μ-nBu)]∞ (M = Na or K), are also revealed though these breakdown to their homometallic components in donor solvent as revealed through NMR and DOSY studies

MOS11: A New Component in the mRNA Export Pathway

Nucleocytoplasmic trafficking is emerging as an important aspect of plant immunity. The three related pathways affecting plant immunity include Nuclear Localization Signal (NLS)–mediated nuclear protein import, Nuclear Export Signal (NES)–dependent nuclear protein export, and mRNA export relying on MOS3, a nucleoporin belonging to the Nup107–160 complex. Here we report the characterization, identification, and detailed analysis of Arabidopsis modifier of snc1, 11 (mos11). Mutations in MOS11 can partially suppress the dwarfism and enhanced disease resistance phenotypes of snc1, which carries a gain-of-function mutation in a TIR-NB-LRR type Resistance gene. MOS11 encodes a conserved eukaryotic protein with homology to the human RNA binding protein CIP29. Further functional analysis shows that MOS11 localizes to the nucleus and that the mos11 mutants accumulate more poly(A) mRNAs in the nucleus, likely resulting from reduced mRNA export activity. Epistasis analysis between mos3-1 and mos11-1 revealed that MOS11 probably functions in the same mRNA export pathway as MOS3, in a partially overlapping fashion, before the mRNA molecules pass through the nuclear pores. Taken together, MOS11 is identified as a new protein contributing to the transfer of mature mRNA from the nucleus to the cytosol

Caracterisation genetique de la proteine C31, une sous-unite acide de l'ARN polymerase C de Saccharomyces cerevisae

SIGLEINIST T 72632 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc