A new synthetic route to monophosphaferrocenes

Phosphacyclopentadienyl anions (A) derived from 1 phenylphospholes cleave the η⁶-bonded arene from η⁶-arene-η⁵-cyclopentadienyliron(II) cations (B)via nucleophilic attack at iron to yield η⁵-cyclopentadienyl- η⁵-phosphacyclopentadienyliron(II) sandwich compounds (C).

The reaction provides a versatile synthetic route to phosphaferrocenes with one general reaction giving a pathway to phosphaferrocenes with greatly varying degrees of ring substitution.     

Heme-peptide/protein ions and phosphorous ligands: search for site-specific addition reactions

High-resolution Fourier transform ion cyclotron resonance mass spectrometry is employed to gain thorough kinetics and thermodynamics information on the reaction of free and ligated heme-type ions with selected ligands, with the aim of obtaining an insight into the coordination environment of the prosthetic group in a variety of biomolecular ions. Adopting a stepwise approach towards systems of increasing complexity, we examined the reactivity of free gaseous iron(III) protoporphyrin IX ions, Fe(III)-heme(+), of the charged species from microperoxidase-11 (MP11) (covalently peptide bound heme), and of the multiply charged ions from heme proteins, namely, cytochrome c (cyt c) and myoglobin (examples of noncovalently protein bound hemes). Among an array of test compounds allowed to react with Fe(III)-heme(+), OP(OMe)(3) and P(OMe)(3) proved to be similarly efficient ligands in the first addition step, yet displayed markedly distinct reactivity towards heme iron already engaged in axial coordination. The ease with which P(OMe)(3) acts as a second axial ligand is exploited to probe structural and conformational features of biomolecular ions. In this way, circumstantial evidence is gained of a folded conformation of +2 charge state ions from MP11 and an elongated one for the +3 charge state ions. Similarly, both the general reaction pattern and detailed kinetics and thermodynamics data point to a regiospecific addition reaction of P(OMe)(3) directed at the heme iron within multiply charged ions from cyt c. This unprecedented example of ion-molecule reaction which specifically involves a prosthetic group belonging to protein ions stands in contrast to the multiple, nonspecific interactions established by OP(OMe)(3) molecules with the protonated sites of multiply charged cyt c and apomyoglobin ions. This finding may develop and provide sensitive probes of the structure and bonding features of protein ions in the gas phase.     

A new synthetic route to 2- and 4-methoxyestradiols by nucleophilic substitution

A new snythetic route to 2- and 4-methoxyestradiols is described. Benzo-15-crown-5 with CuI catalyzes the specific nucleophilic substitution at the carbon atom carrying a non-activated halogen on ring A of the estradiol.     

A new synthetic route to pyrogallolestrogen dimethyl ethers by nucleophilic substitution of 2,4-dibromoestrogens

A novel synthetic route to pyrogallolestrogen dimethyl ethers was developed. Benzo-15-crown-5 with CuI catalyses the specific nucleophilic substitution of bromo atoms by methoxide ions.     

A new synthetic route to thioacetyl-functionalised 2,2′-bipyridyl complexes

A fast two-step synthetic approach for 4,4′-thioacetyl-functionalised 2,2′-bipyridine is described. Ethylcarbamoyl groups are used as spacers between the sulfur atoms and the pyridyl rings. Both reactions proceed in a highly selective manner. The coordinating properties of the ligand have been assessed.     

1-Aryl-4,6-diamino-1,2-dihydrotriazine as antimalarial agent: a new synthetic route

Some novel derivatives of 1-aryl-4,6-diamino-1,2-dihydrotriazines have been synthesized using neat technology under microwaves. These were tested in vitro against both sensitive and resistant Plasmodium falciparum strains for antimalarial activity.     

Pollination of Campomanesia phaea (Myrtaceae) by night‐active bees: a new nocturnal pollination system mediated by floral scent

• Bees are the most important diurnal pollinators of angiosperms. In several groups of bees a nocturnal/crepuscular habit developed, yet little is known about their role in pollination and whether some plants are adapted specifically to these bees. We used a multidisciplinary approach to investigate the reproductive biology and to understand the role of nocturnal/crepuscular bees in pollination of Campomanesia phaea (Myrtaceae), popularly named cambuci.
• We studied the floral biology and breeding system of C. phaea. We collected the floral visitors and tested the pollinators' effectiveness. We also determined the floral scents released at night and during daytime, and studied behavioural responses of crepuscular/nocturnal bees towards these scents.
• The flowers of cambuci were self‐incompatible and had pollen as the only resource for flower visitors. Anthesis lasted around 14 h, beginning at 04:30 h at night. The flowers released 14 volatile compounds, mainly aliphatic and aromatic compounds. We collected 52 species of floral visitors, mainly bees. Nocturnal and crepuscular bees (four species) were among the most frequent species and the only effective pollinators. In field bioassays performed at night, nocturnal/crepuscular bees were attracted by a synthetic scent blend consisting of the six most abundant compounds.
• This study describes the first scent‐mediated pollination system between a plant and its nocturnal bee pollinators. Further, C. phaea has several floral traits that do not allow classification into other nocturnal pollination syndromes (e.g. pollinator attraction already before sunrise, with pollen as the only reward), instead it is a plant specifically adapted to nocturnal bees.

     

A vinyl sulfone-modified carbohydrate mediated new route to aminosugars and branched-chain sugars

This minireview describes syntheses of various vinyl sulfone-modified carbohydrates and their reactions with nitrogen and carbon nucleophiles for accessing a wide range of aminosugars and branched-chain sugars.     

One-step preparation of dithiocarboimidate ligands by addition of phenylisothiocyanate to tetrathiomolybdate

Reaction of C₆H₅NCS with led to the formation of a dinuclear complex of molybdenum(V) with two dithiocarboimidate ligands, (NEt₄)₂[Mo₂(S)₂(μ-S)₂(η²-S₂CN(C₆H₅))₂] · 0.5CO(CH₃)₂. The crystallization of 1 is systematically accompanied by the formation of 4-phenyl-3,5-diphenylimino[1,2,4]-dithiazolidine [(C₆H₅)₃N₃C₂S₂] (2). The two compounds have been structurally characterized by XRD and a reaction scheme is proposed.     

FoxO: a new addition to the ESC cartel

The forkhead box O (FoxO) family is involved in diverse cellular processes such as tumor suppression, stress response, and metabolism. In a recent Nature Cell Biology Letter, Zhang et?al. (2011) uncover a novel role for FoxO proteins in regulating the identity of human ESCs.     

New potential antibacterials: a synthetic route to N-aryloxazolidinone/3-aryltetrahydroisoquinoline hybrids

A synthetic route to a new structural type of potential antibacterials, with a hybrid 3-aryltetrahydroisoquinoline-6,7-diol/N-aryloxazolidinone structure, is reported. The synthesis involves the successive construction of the 3-aryltetrahydroisoquinoline and 4-substituted oxazolidinone moieties, the latter taking advantage of the functionalization at the para position of the aryl group.     

A synthetic route to a novel type of conformationally constrained N-aryloxazolidinones

The synthesis of N-aryloxazolidinone 1, a conformationally constrained analog of linezolid embodying a tricyclic pyrrolo[1,2-a][4,1]benzoxazepine moiety as the N-aryl substituent, is reported. The synthetic route involves the successive construction of the pyrrole, oxazepine, and oxazolidinone rings, with incorporation of the isoxazolylamino moiety in the last synthetic steps.     

De novo synthetic route to a combinatorial library of peptidyl nucleosides

A stereoselective synthetic route has been developed for the combinatorial synthesis of a structurally unique class of C-4' side chain modified peptide-linked nucleosides. The synthetic strategy and approach involves initial synthesis of a strategically functionalized amino butenolide template, utilizing L-serine as a chiral starting material. Subsequent transformation of the above lactone to C4' aminoalkyl substituted nucleosides, followed by the peptidic coupling of the C4' side chain amine with various amino acids completed the syntheses of the target peptidyl nucleosides. Employing the above route, and utilizing a combination of easily available nucleobases (4) and amino acids (6) as the two diversity elements, synthesis of a 24-member combinatorial library of the title peptide-linked nucleosides has been accomplished.     

Ca2+ signalling: a new route to NAADP

The LKB1 serine/threonine kinase is a tumour suppressor responsible for the inherited familial cancer disorder Peutz-Jeghers syndrome and is inactivated in a large percentage of human lung cancers. LKB1 acts a master kinase, directly phosphorylating and activating a family of 14 AMPK (AMP-activated protein kinase)-related kinases which control cell metabolism, cell growth and cell polarity. In this issue of the Biochemical Journal, Hardie and colleagues discover an alternative splice form of LKB1 that alters the C-terminus of the protein containing a few known sites of post-translational regulation. Although widely expressed, the short isoform (LKB1(s)) is the sole splice isoform expressed in testes, and its expression peaks at the time of spermatid maturation. Male mice lacking the LKB1(s) isoform have dramatic defects in spermatozoa, resulting in sterility.     

Asymmetric cell division: a new way to divide unequally

It has long been known that cells can divide unequally by shifting the mitotic spindle to one side. Two recent reports identify an alternative way to generate daughter cells of different sizes.