Novel synthesis of the ocular age pigment A2-E: new method for substituted pyridine synthesis via azaelectrocyclization

(Z)-alpha-haloacrylates: an exceptionally stereoselective preparation via Cr(II)-mediated olefination of aldehydes with trihaloacetates

(Z)-alpha-Fluoro-, (Z)-alpha-chloro-, and (Z)-alpha-bromoacrylates were obtained with unprecedented yield and stereocontrol (>99%) via addition of the corresponding commercial trihaloacetates to aldehydes at room temperature using stoichiometric Cr(II) salts or catalytic Cr(II) with a regeneration system. The intermediate 2,2-dihalo-3-hydroxy adducts could be isolated in good yields under conditions of limited reagent at 0 degrees C.

Highly stereoselective asymmetric 6pi-azaelectrocyclization utilizing the novel 7-alkyl substituted cis-1-amino-2-indanols: formal synthesis of 20-epiuleine

Highly stereoselective asymmetric 6pi-azaelectrocyclization was achieved with generality, based on the reaction between the (E)-3-carbonyl-2,4,6-trienal compounds and the (-)-7-alkyl-cis-1-amino-2-indanol derivatives as the effective novel chiral amines. Furthermore, the chiral auxiliaries of the cyclized products obtained were efficiently removed by the novel manganese dioxide oxidation under remarkably mild conditions, and the method was successfully applied to the formal synthesis of optically active 20-epiuleine.

Fluorescent pigments of the retinal pigment epithelium and age-related macular degeneration

The major hydrophobic fluorophore of the retinal pigment epithelium (RPE) is A2E, a pyridinium bis-retinoid derived from all-trans-retinal and phosphatidyl-ethanolamine. The accumulation of fluorophores such as A2E is implicated in the pathogenesis of age-related macular degeneration (AMD), a disease associated with the deterioration of central vision and a leading cause of blindness in the elderly. Recent chemical and biological studies have provided insight into the synthesis and biosynthesis of A2E, the spectroscopic properties of this pigment, and the role of A2E and RPE cell death.

Significant acceleration of 6 pi-azaelectrocyclization resulting from a remarkable substituent effect and formal synthesis of the ocular age pigment A2-E by a new method for substituted pyridine synthesis

The remarkable acceleration of 6 pi-azaelectrocyclization due to the combination of the C4-carbonyl and the C6-alkenyl or phenyl substituents in 1-azatrienes was found. This observation was rationalized by considering the remarkable orbital interaction between the HOMO and LUMO of 1-azatrienes, which were obtained by molecular orbital calculations. The formal synthesis of the unusual retinal metabolite, A2-E, was achieved by two types of the new one-pot synthesis of substituted pyridines by utilizing the obtained facile 6 pi-azaelectrocyclization, one of which is compatible with the proposed metabolic pathway of A2-E.