Jitendra A. Sattigeri

Chemoselective reductive deoxygenation of α,β-unsaturated ketones and allyl alcohols

A simple and convenient procedure for a highly chemoselective reductive deoxygenation of α,β-unsaturated ketones and allyl alcohols to olefins by sodium cyanoborohydride and boron trifluoride etherate in dry THF is described.

A stereoselective total synthesis of bakkenolide-A (fukinanolide)

A highly stereoselective synthesis of bakkenolide-A (fukinanolide. 1a) employing the radical mediated spirannulation methodology is described.

Reaction of spironaphthalenones with hydroxylamine hydrochloride: Part IV

Reaction of 1-methoxynaphthalene with 1-formylnaphthalene in presence of n-BuLi/TMEDA, followed by deoxygenation and demethylation gave the bisnaphthol 6. Oxidation of 6 with KOBr yielded the spironaphthalenones 4a-b and 5a-b. The spironaphthalenones 3a-c on reaction with NH2OH.HCl gave naphth[2,1-c]isoxazole derivatives 9a-c. While similar reaction of 4a-b gave the pyrrolotropones 11a-b, spironaphthalenones 5a-b afforded the naphth[1,2-c]isoxazole derivatives 12a-b.

A radical cyclisation based cyclopentenone annulation of allyl alcohols

A four-step cyclopentenone annulation reaction of allylic alcohols employing a 5-exo-trig radical cyclisation reaction of mixed allyl methyl ketals of bromoacetone as the key step is described. The annulated product 12b obtained from 2,3-dimethylcyclohexenol has been further elaborated into (±)-epibakkenolides employing a 5-exo-dig radical cylisation reaction based α-spiro-β-methylene-γ-butyrolactone annulation methodology.

Reaction of spironaphthalenones with hydroxylamine: Part I. A reinvestigation of the mechanism

Spironaphthalenones 1b–g on reaction with hydroxylamine hydrochloride gave the expected pyrrolotropones 2b–g. Furanotropone 6, postulated as an intermediate in the formation of pyrrolotropones, remained unchanged on reaction with hydroxylamine hydrochloride in ethanol. Reaction of unsymmetrical spironaphthalenones 1h–o with NH2OH.HCl gave the rearranged pyrrolotropones 2h–o.

Novel reduction (Zn-AcOH) of DDHQ esters. A new route to tropone synthesis☆

Zn/acetic acid reaction of DDHQ esters 1 a-d gave the saturated acids 3 a-d and the hydrocarbons 7 a-d. The intermediacy of the aldehydes 10 and 11 in the formation of the products has been established. Oxidation of hydrocarbons 7a and 7b gave the corresponding tropones (5a and 5b).

Dispironaphthalenones and spironaphthalenones as novel dehydrogenation reagents

Abstract Dehydrogenation of a number of dihydroaromatic substrates has been carried out using either dispironaphthalenone 1 or spironaphthalenones 2 & 3 as dehydrogenating agents. The reaction is over in refluxing mesitylene in 1– hr and the yields of the aromatised products are fairly good (65–70%).

Cyclopentaannulation of allyl alcohols via a radical cyclisation reaction. Total synthesis of 4-epibakkenolide-A

A four step cyclopentaannulation methodology starting from allyl alcohols using 5-exo-trig radical cyclisation as the key reaction, and its application to the total synthesis of 4-epibakkenolide is described.