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We have developed a simple method for the chemoselective aromatization of tetrahydro-β-carboline with selective nondeallylation O-allyl groups in the presence of iodine (100 mol %) in dimethyl sulfoxide/H 2 O 2 . A convergent approach toward the oxidative aromatization with selective deallylation (deprotection) of O-allyl-tetrahydro-β-carboline using iodine in dimethyl sulfoxide/HCl has been described. The present protocol contains cheap catalyst, easy work up, normal reaction conditions, and high selectivity.

A new protocol for the chemoselective aromatization of tetrahydro-β-carboline-3-carboxylic acids to direct biomimetic one step synthesis of β-carboline-3-carboxylic acids 2 A-L using catalytic amount of I 2 in DMSO/H + produces very good yield. This method was also successfully extended for the aromatiza-tion of tetrahydro-β-carboline-3-methyl esters 5 A-G as well as one-step synthesis of Marinacarbolines-D analog, respectively. Further, the mechanism and role of iodine-DMSO in aromatization has been studied by Density Functional Theory Calculation.[a] S.

Synthesis of flavones from 2'-allyloxy-α, β-dibromochalcones has been described. The iodine induced oxidative cyclization of 2'-allyloxy-α, β-dibromochalcones results into the formation of 3-bromoflavanones which ultimately gives flavones. Dehydrobromination of 3-bromoflavanone to give flavone is the preferred reaction over dehydrogenation.

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