Semi-synthetic diversification of coronarin D, a labdane diterpene, under Ugi reaction conditions.

The prevalence of 5-hydroxydihydrofuran-2(3)-one moiety in natural products is exploited for the first time using coronarin D, a labdane diterpene, to afford Ugi reaction product and interrupted Ugi product . The potential of the Ugi reaction was further extended to l-phenylalanine, 2-aminopyridine, and d-glucosamine, which afforded Ugi reaction products , , and , respectively. Cytotoxicity studies in RAW cells reveal that compounds and were non-toxic up to 50 µM, and these compounds were able to reduce the LPS stimulated NO production in RAW cells in par with the standard anti-inflammatory drug dexamethasone.

Dienaminodioate based multicomponent reactions with post-benzylic oxidative transformations mediated by DDQ.

Multicomponent reactions (MCRs) using dienaminodioate with post-benzylic oxidative transformation mediated by DDQ that afforded a diverse array of products are described. An unprecedented rearrangement of 1,2-dihydropyridines (1,2-DHPs), 3CR products, to 2-pyridones in good yields with a broad substrate scope by DDQ-mediated benzylic oxidation via a pyridinium intermediate is reported. Treatment of the pyridinium intermediate with tert-butyl isocyanide afforded isomerized 1,2-DHPs, analogous to Ritter amides.

A metal-free one-pot cascade synthesis of highly functionalized biaryl-2-carbaldehydes.

A metal-free one-pot cascade annulation of acyclic substrates dienaminodioate, cinnamaldehydes and allyl amine was achieved for the synthesis of polyfunctional biaryl-2-carbaldehydes. The reaction proceeds at room temperature by a trifluoroacetic acid mediated Diels-Alder pathway. Synthetic applications of the resulting biaryl-2-carbaldehyde have been demonstrated by conversion into an array of diverse molecules with biological and materials chemistry relevance.