New Organolithium Addition Methodology to Diversely Functionalized Indoles
作者:Claire M. Coleman、Donal F. O'Shea
DOI:10.1021/ja034283h
日期:2003.4.1
A novel synthetic approach to diversely functionalized indoles is described. Boc-protected ortho-aminostyrenes undergo an alkyllithium addition reaction, thereby generating a lithiated intermediate, which upon reaction with specific electrophiles sets up a cascade reaction process between the reacted electrophile and ortho-amino substituent, facilitating an in situ ring closure, followed by dehydration
Indole Synthesis by Controlled Carbolithiation of <i>o</i>-Aminostyrenes
作者:Albane Kessler、Claire M. Coleman、Patchanee Charoenying、Donal F. O'Shea
DOI:10.1021/jo048723e
日期:2004.11.1
An effective synthesis of the functionalized indole ring system has been developed from substituted o-aminostyrene starting material. Our methodology involves a novel cascade reaction sequence of alkyllithium addition to the styrene double bond and subsequent trapping of the intermediate organolithium with a suitable electrophile, followed by an in situ ring closure and dehydration to generate the indole ring. This new reaction sequence allows for the introduction of molecular diversity at all positions on the indole scaffold. The procedure was shown to be successful with a range of both C and N substituents on the o-aminostyrenes. The reaction sequence was tolerant to the reactivity range of alkyllithiums such as tert-, sec-, and n-butyllithium. The electrophiles used were DMF, which generated indole products with C-2 unsubstituted, and nitriles, which incorporated the nitrile substituent at C-2. The o-aminostyrene starting materials were generated by a Pd-catalyzed cross-coupling reaction of a vinyl boronic acid equivalent with the readily available substituted o-bromoanilines.
Indole synthesis from N-allenyl-2-iodoanilines under mild conditions mediated by samarium(<scp>ii</scp>) diiodide