Synthesis and biological evaluation of longanlactone analogues as neurotrophic agents.

Longanlactone analogues were synthesized using a route featuring Friedel-Crafts acylation, Sonogashira coupling and 1,3-dipolar cycloaddition reactions. Structure-activity relationships were investigated for neurotrophic activity. Compound 6 was found to have the most potent neurotrophic activity among all the synthesized analogues in Neuro2a cells as evidenced by a battery of in vitro/cell based assays for assessment of neurogenic and potential neurotrophic activity including neurite outgrowth assay and real time PCR for popular markers of augmented neurotrophic activity. Compound 6 might serve as a template for further development of highly effective neurotrophic molecules.

One-Pot Sequential Propargylation/Cycloisomerization: A Facile [4+2]-Benzannulation Approach to Carbazoles.

A novel one-pot [4+2]-benzannulation approach to substituted carbazoles is accomplished by acid-catalyzed C3-propargylation of 2-alkenyl/aryl indoles with 1-aryl propargylic alcohols, followed by cycloisomerization. A variety of 2-alkenylated indoles and 2-aryl/heteroaryl indoles successfully participated in this tandem reaction with 1-aryl/heteroaryl propargylic alcohols to provide diversely substituted and annulated carbazoles, as well as an aza[5]helicene.

Total synthesis and revision of the absolute configuration of seimatopolide B.

The asymmetric total synthesis of natural seimatopolide B along with its enantiomer is described starting from readily available 5-hexen-1-ol and 3-buten-1-ol. The key steps involved are Jacobson hydrolytic kinetic resolution, proline-catalyzed α-hydroxylation, Yamaguchi esterification and ring-closing metathesis. This asymmetric total synthesis necessitates the revision of the originally assigned (3R, 6S, 9S)-configuration to (3S, 6R, 9R).

An atom- and pot-economical consecutive multi-step reaction approach to polycyclic aromatic hydrocarbons (PAHs).

A novel one-pot benzannulation reaction has been developed for the synthesis of substituted polycyclic aromatic hydrocarbons (PAHs) from the direct coupling of propargylic aldehydes/alcohols with 1,1-diarylethanol through an atom-economical uninterrupted three/four-step reaction sequence under mild and metal-free reaction conditions. The strategy involves an acid-catalyzed dehydration and carbon-carbon bond formation followed by DBU-promoted cycloisomerization. Naphthalene and phenanthrene were obtained via mono-benzannulation, and chrysene, picene and benzopicene were obtained involving consecutive di-benzannulation reactions in good yields starting from easily accessible starting materials.

Novel [4 + 2]-benzannulation to access substituted benzenes and polycyclic aromatic and benzene-fused heteroaromatic compounds.

A common [4 + 2]-benzannulation of Morita-Baylis-Hillman acetates of acetylenic aldehydes with boronic acids has been developed for the synthesis of aromatic and heteroaromatic compounds through tandem allylic substitution/hydroarylative cycloisomerization process. This method provides a facile and general route to substituted benzenes, naphthalenes, other polycyclic aromatics, and various benzene-fused heteroaromatic compounds such as benzofuran, benzothiophene, indole, and carbazoles.