O(-)---C interactions and bond formation in 1-naphtholate anions with peri-located electrophilic carbon centres

The first peri interactions between naphtholate oxyanions and electrophilic double bonds are described. Tetramethylguanidine forms crystalline salts with 8-acetyl- and 8-benzoyl-naphthol which show O---C distances for the anions in the range 2.558-2.618 Å and small increases in carbonyl pyramidalities over the corresponding naphthols, whereas DMAP forms only hydrogen bonded complexes. Replacement of the acyl group with an alkene leads to intramolecular O-C bond formation for just the most electron deficient alkenes, with long peri O-C bonds (1.508 and 1.521 Å) observed in one case. However, both cyclised and uncyclised examples can be deprotonated to give cyclic structures according to NMR, and DFT calculations suggest very long peri- O-C bond lengths of 1.540 and 1.622 Å for two of these anions

Interaction, bond formation or reaction between a dimethylamino group and an adjacent alkene or aldehyde group in aromatic systems controlled by remote molecular constraints

Peri-peri interactions in naphthalene systems control the degree of bond formation between a peri-dimethylamino group and a polarised alkene or aldehyde group. Two peri-phenyl groups, which repel, induce closer N⋯C interactions or bond formation, while the ethylene link in the corresponding acenaphthene system has the opposite effect, and for the more electron-deficient alkenes lead to formation of a fused azepine ring initiated by the tert-amino effect. In related 1,8-fluorene derivatives N⋯C interactions occur for an aldehyde and a moderately polarised alkene, but fused azocines are formed when the alkene is more reactive

Modelling of an aza-Michael reaction from crystalline naphthalene derivatives containing peri–peri interactions: very long N–C bonds?

The separation between a pair of peri-located dimethylamino and ethene-2,2-dinitrile groups in a naphthalene molecule, which models the progress of a Michael reaction, can be controlled by the installation of a short ethylene bridge or the introduction of repulsive interactions at the opposite set of peri positions. Introduction of a dimethylammonium substituent produced a hydrated chloride salt in which the Me2N⋯C(H)[double bond, length as m-dash]C(CN)2 separation between reactive groups decreases, reversibly, from 2.167 Å at 200 K to 1.749 Å at 100 K, with the maximum rate of change in the range 128–140 K, which was studied by variable temperature X-ray crystallography and solid state NMR. From these and other crystallographic data a correlation between Me2N⋯C bond formation and alkene bond breaking was constructed for the first step of an aza-Michael reaction

One step conversion of 1,5-bis(dimethylamino)naphthalene to salts of “back to back” bis-acridine derivatives

Oxidation of 1,5-bis(dimethylamino)naphthalene with iodine leads directly to a bis(dimethyliminium) derivative of acridino[2,1,9,8-klmna]acridine, containing six fused six-membered rings, as a bis triiodide salt. The cation has a twisted structure due to the minimisation of peri interactions between each dimethyliminium group and a hydrogen atom. Use of TCNQ as oxidizing agent leads to the same dication as a tetrakis(TCNQ) salt, while use of TCNQ-F4 gave a related monocation which is dimethylated on a ring nitrogen atom

A novel and highly stereoselective route for the synthesis of non-racemic 3-substituted isoindolin-1-one targets

A new, versatile and highly stereoselective approach for the synthesis of non-racemic 3-substituted isoindolin-1-ones is described from a readily available chiral template. The potential of this new protocol is demonstrated through the synthesis of an enantiomerically enriched 3-alkyl N-H isoindolin-1-one target with an e.e. of 98%

Multiple interactions between the alpha2C- and beta1-adrenergic receptors influence heart failure survival

<p>Abstract</p> <p>Background</p> <p>Persistent stimulation of cardiac β₁-adrenergic receptors by endogenous norepinephrine promotes heart failure progression. Polymorphisms of this gene are known to alter receptor function or expression, as are polymorphisms of the α_2C-adrenergic receptor, which regulates norepinephrine release from cardiac presynaptic nerves. The purpose of this study was to investigate possible synergistic effects of polymorphisms of these two intronless genes (<it>ADRB1 </it>and <it>ADRA2C</it>, respectively) on the risk of death/transplant in heart failure patients.</p> <p>Methods</p> <p>Sixteen sequence variations in <it>ADRA2C </it>and 17 sequence variations in <it>ADRB1 </it>were genotyped in a longitudinal study of 655 white heart failure patients. Eleven sequence variations in each gene were polymorphic in the heart failure cohort. Cox proportional hazards modeling was used to identify polymorphisms and potential intra- or intergenic interactions that influenced risk of death or cardiac transplant. A leave-one-out cross-validation method was utilized for internal validation.</p> <p>Results</p> <p>Three polymorphisms in <it>ADRA2C </it>and five polymorphisms in <it>ADRB1 </it>were involved in eight cross-validated epistatic interactions identifying several two-locus genotype classes with significant relative risks ranging from 3.02 to 9.23. There was no evidence of intragenic epistasis. Combining high risk genotype classes across epistatic pairs to take into account linkage disequilibrium, the relative risk of death or transplant was 3.35 (1.82, 6.18) relative to all other genotype classes.</p> <p>Conclusion</p> <p>Multiple polymorphisms act synergistically between the <it>ADRA2C </it>and <it>ADRB1 </it>genes to increase risk of death or cardiac transplant in heart failure patients.</p