Direct Synthesis of Indoles from Azoarenes and Ketones with Bis(neopentylglycolato)diboron Using 4,4′-Bipyridyl as an Organocatalyst was written by Misal Castro, Luis C.;Sultan, Ibrahim;Nishi, Kohei;Tsurugi, Hayato;Mashima, Kazushi. And the article was included in Journal of Organic Chemistry in 2021.Synthetic Route of C12H15NO3S This article mentions the following:
Multifunctionalized indole derivatives were prepared by reducing azoarenes in the presence of ketones and bis(neopentylglycolato)diboron (B2nep2) with a catalytic amount of 4,4′-bipyridyl under neutral reaction conditions, where 4,4′-bipyridyl acted as an organocatalyst to activate the B-B bond of B2nep2 and form N,N’-diboryl-1,2-diarylhydrazines as a key intermediate. Further reaction of N,N’-diboryl-1,2-diarylhydrazines with ketones afforded N-vinyl-1,2-diarylhydrazines, which rearranged to the corresponding indoles via the Fischer indole mechanism. This organocatalytic system was applied to diverse alkyl cyclic ketones, dialkyl, and alkyl/aryl ketones, including heteroatoms. Me alkyl ketones gave the corresponding 2-methyl-3-substituted indoles in a regioselective manner. This protocol allowed us to expand the preparation of indoles having high compatibility with not only electron-donating and electron-withdrawing groups but also N- and O-protecting functional groups. In the experiment, the researchers used many compounds, for example, 1-Tosylpiperidin-4-one (cas: 33439-27-9Synthetic Route of C12H15NO3S).
1-Tosylpiperidin-4-one (cas: 33439-27-9) belongs to piperidine derivatives. The piperidine ring can be found not only in more than half of the currently known structures of alkaloids, but also in many natural or synthetic compounds with interesting biological activities. Fluorinated piperidines are also the subject of continued interest in medicinal chemistry, for example in the synthesis of selective dipeptidyl peptidase II (DPP II) inhibitors. Piperidine derivatives are also used in solid-phase peptide synthesis (SPPS) and many degradation reactions.Synthetic Route of C12H15NO3S
Referemce:
Piperidine – Wikipedia,
Piperidine | C5H11N – PubChem