Shuleewan Rajviroongit

Metal ion catalysed asymmetric 1,3-dipolar cycloaddition reactions of imines of α-amino esters

Abstract Cycloaddition of a range of imines of α-amino esters to homochiral menthyl acrylate proceeds with complete asymmetric induction at room temperature in the presence of silver(I), lithium(I) and thallium(I) salts. The imine of 2-aminomethylpyridine reacts similarly. Reversal of cycloaddition regiochemistry, together with complete asymmetric induction, occurs when titanium (IV) complexes are used as catalysts. The absolute configuration of one of the cycloadducts has been established by X-ray crystallography.

Biomimetic transformation and biological activities of globiferin, a terpenoid benzoquinone from Cordia globifera.

A new 10-membered ring meroterpene (1), named globiferin, was isolated from root extracts of Cordia globifera. Biomimetic transformations of 1 and its derivatives, either by acid cyclization or by Cope rearrangement, provided information relating to the biogenesis of cordiachromes A-C. Globiferin (1) underwent Cope rearrangement upon refluxing in xylene and DMSO-d(6) to yield cordiachrome C (3) and cordiaquinol C (4), respectively. Heating in DMSO-d(6) resulted in an unexpected reduction of a quinone moiety. Globiferin diacetate (1b) cyclized under acidic conditions to give compounds 10 and 11, respective derivatives of natural cordiachromes B (2) and A (12). The present study indicates that globiferin (1) is a genuine intermediate for the biosynthesis of cordiachromes in Cordia species. Compounds 1 and 3 exhibited significant antimycobacterial activity, with MIC values of 6.2 and 1.5 mug/mL, respectively. Antimalarial, antifungal, and cytotoxic activities of 1 and its derivatives were also evaluated.

Synthesis of N-substituted 4-methylene-3,4-dihydro-1(2H)-isoquinolin-1-ones via a palladium-catalysed three-component process

A novel palladium-catalysed three-component cascade process involving 2-iodobenzoyl chloride or methyl 2-iodobenzoate, allene and primary aliphatic or aromatic amines furnishes N-substituted 4-methylene-3,4-dihydro-1(2H)-isoquinolin-1-ones in good yield.

Flash vacuum pyrolysis of cyclopropene–anthracene adducts

Flash vacuum pyrolysis of cyclopropene–anthracene adducts 4, 6 and 8 results in ring opening of the cyclopropane moiety to yield 5, 7 and 5e, respectively.