Asymptotic behavior of solutions of forced nonlinear neutral delay differential equations with impulses

Sufficient conditions for asymptotic behavior of the solutions of nonlinear forced neutral delay differential equations with impulses are found. The results given in [2,4,6,7] are generalized and improved.     

Synthesis of chiral 4-hydroxy-2,3-unsaturated carbonyl compounds from 3,4-epoxy alcohols by oxidation: application in the formal synthesis of macrosphelide A

An interesting transformation during the oxidation of 3,4-epoxy alcohols 1a-d, derived from the corresponding homoallylic alcohols, led to the formation of 4-hydroxy-2,3-unsaturated carbonyls 2a-d in very good yields. One of these products 2c was transformed into the functionalised carboxylic acid 5, an advanced stage intermediate from which the total synthesis of macrosphelide A has been reported.     

Thiol-mediated radical cyclization: regioselective formation of indole-annulated sulfur heterocycles by tandem cyclization

Indole-2-yl-prop-2-ynyl sulfides, under thiophenol-mediated alkenyl radical cyclization conditions, afforded exclusively 4-thiophenyl-2,3,4,9-tetrahydrothiopyrano[2,3-b]indoles or 3-thiophenylmethyl-2,3,8-trihydrothieno[2,3-b]indoles depending on the substituent at the indole nitrogen.     

Synthesis and characterization of Boc-protected 4-amino- and 5-amino-pyrrole-2-carboxylic acid methyl esters

Syntheses of Boc-protected 4-amino- and 5-amino-pyrrole-2-carboxylic acid methyl esters have been achieved and the structures of these compounds have been fully characterized by detailed NMR studies.     

Nucleation of β-hairpin structure in a pyrrole amino acid containing peptide

Synthesis and conformational studies of two short peptides containing pyrrole amino acids (1, Paa), Boc-Paa-Paa-d-Pro-Gly-Xaa-Paa-Paa-OMe (2: Xaa=Ala; 3: Xaa=Val), were carried out in which it was established that replacement of Ala in 2 with a Val residue helps peptide 3 to adopt a well-defined β-hairpin conformation in a nonpolar solvent, like CDCl₃.     

Organometallic building blocks with amino-substituted cyclopentadienyl and boratabenzene ligands for the synthesis of heterometallic complexes and clusters

A comparative study of the reactivity of isolobal rhenium and molybdenum carbonylmetallates containing a borole, in [Re(eta5-C4H4BPh)(CO)3]- (2), a boratanaphthalene, in [Mo(eta5-2,4-MeC9H6BMe)(CO)3]- (4a) and [Mo(eta5-2,4-MeC9H6BNi-Pr2)(CO)3]- (4b), a boratabenzene, in [Mo(eta5-3,5-Me2C5H3BNi-Pr2)(CO)3]- (6) or a dimethylaminocyclopentadienyl ligand, in [Mo(eta5-C5H4NMe2)(CO)3]- (7), toward palladium(II), gold(I), mercury(II) and platinum(II) complexes has allowed an evaluation of the role of these pi-bonded ligands on the structures and unprecedented coordination modes observed in the resulting metal-metal bonded, heterometallic complexes. The new metallate 6 was reacted with [AuCl(PPh3)], and with 1 or 2 equiv. HgCl2, which afforded the new heterodinuclear complexes [Au{Mo(eta5-3,5-Me2C5H3BNi-Pr2)(CO)3}(PPh3)] (Mo-Au) (10) and [Hg{Mo(eta5-3,5-Me2C5H3BNi-Pr2)(CO)3}Cl] (Hg-Mo) (11) and the heterometallic chain complex [Hg{Mo(eta5-3,5-Me2C5H3BNi-Pr2)(CO)3}2] (Mo-Hg-Mo) (12), respectively. Reactions of the new metallate 7 with HgCl2, trans-[PtCl2(CNt-Bu)2] and trans-[PtCl2(NCPh)2] yielded the heterodinuclear complex [Hg{Mo(eta5-C5H4NMe2)(CO)3}Cl] (Mo-Hg) (15), the heterotrinuclear chain complexes trans-[Pt{Mo(eta5-C5H4NMe2)(CO)3}2(CNt-Bu)2] (Mo-Pt-Mo) (16) and trans-[Pt{Mo(eta5-C5H4NMe2)(CO)3}2(NCPh)2] (Mo-Pt-Mo) (17), the mononuclear complex [Mo(eta5-C5H4NMe2)(CO)3Cl] (18), the lozenge-type cluster [Mo2Pt2(eta5-C5H4NMe2)2(CO)8] (19) and the heterodinuclear complex [[upper bond 1 start]Pt{Mo(eta5-C5H4N[upper bond 1 end]Me2)(CO)3}(NCPh)Cl](Mo-Pt) (20), respectively. The complexes 11, 16, 17.2THF, 18 and 20 have been structurally characterized by X-ray diffraction and 20 differs from all other compounds in that the dimethylaminocyclopentadienyl ligand forms a bridge between the metals.     

A small molecule discrimination map of the antibiotic resistance kinome

Kinase-mediated resistance to antibiotics is a significant clinical challenge. These enzymes share a common protein fold characteristic of Ser/Thr/Tyr protein kinases. We screened 14 antibiotic resistance kinases against 80 chemically diverse protein kinase inhibitors to map resistance kinase chemical space. The screens identified molecules with both broad and narrow inhibition profiles, proving that protein kinase inhibitors offer privileged chemical matter with the potential to block antibiotic resistance. One example is the flavonol quercetin, which inhibited a number of resistance kinases in vitro and in vivo. This activity was rationalized by determination of the crystal structure of the aminoglycoside kinase APH(2″)-IVa in complex with quercetin and its antibiotic substrate kanamycin. Our data demonstrate that protein kinase inhibitors offer chemical scaffolds that can block antibiotic resistance, providing leads for co-drug design.