Radical cyclization strategies to terpenoids; syntheses of (±)-β-cuparenone, (±)-laurene and epilaurenes

Radical cyclization of the bromide Image , obtained in 5 steps from the ketone Image , furnished exclusively Image Image 6-endo trig cyclization with out any observable amount of 5-exo trig product Image . 5-Exo dig radical cyclizatlon of the bromo acetate Image , prepared from Image Image the aldehyde Image , followed by routine transformations furnished the cyclopentenone Image , an immediate precursor to β-cuparenone (Image ). Similarly, total synthesis of laurenes Image and Image was achieved Image the 5-exo dig radical cyclization of the xanthate Image , obtained from the aldehyde Image .Syntheses to title compounds based on 5-exo-dig radical cyclisation, along with two unsuccessful approaches to cuparene, are described

A radical cyclisation reaction based strategy to 2,3,5-tri- and tetrasubstituted furans

Synthesis of 2,3,5-trisubstituted furans (5̲), starting from 2-methoxypropene and 1,3-disubstituted propargyl alcohols 3̲ via̲, the radical cyclisation of the bromo acetal 4̲ followed by aromatisation, is reported. Analogously, l-methoxycyclohexene and propargyl alcohols 3̲ furnished the tetrasubstituted furans 6̲

A radical cyclisation reaction based strategy to 2,3,5-tri- and tetrasubstituted furans

Synthesis of 2,3,5-trisubstituted furans ($5$), starting from 2-methoxypropene and 1,3-disubstituted propargyl alcohols $3$, $via$ the radical cyclisation of the bromo acetal $4$ followed by aromatisation, is reported. Analogously, l-methoxycyclohexene and propargyl alcohols $3$ furnished the tetrasubstituted furans $6$

Zeolite as a host for chiral induction

By employing a strategy that involves the use of chirally modified zeolite as the reaction medium, modest enantioselectivity is achieved during photolysis of two ketones capable of undergoing the Norrish-Yang reaction

The Lindlar catalyst revitalized: a highly chemoselective method for the direct conversion of azides to N-(tert-butoxycarbonyl)amines

An exceptionally chemoselective method for the direct conversion of azides to N-(tert-butoxycarbonyl)-protected amines under catalytic transfer-hydrogenation conditions, using the Lindlar catalyst, is reported. The extremely labile functional groups such as N-Cbz, benzyl ester are shown to be inert under the reaction conditions. The present method allows us to synthesize orthogonally protected (N-Cbz & N-Boc) 1,2-diamino systems, which will be immensely useful in organic synthesis