168030-84-0Relevant academic research and scientific papers
Iodine-mediated electrophilic cyclization of 2-alkynyl-1-methylene azide aromatics leading to highly substituted isoquinolines and its application to the synthesis of norchelerythrine
Fischer, Dirk,Tomeba, Hisamitsu,Pahadi, Nirmal K.,Patil, Nitin T.,Huo, Zhibao,Yamamoto, Yoshinori
supporting information; scheme or table, p. 15720 - 15725 (2009/03/12)
The reaction of 2-alkynyl-1-methylene azide aromatics 1 with iodine and/or other iodium donors, such as the Barluenga reagent (Py2IBF 4/HBF4) and NIS, gave highly substituted cyclization products, namely, the 1,3-disubstituted 4-iodoisoquinolines 2, in good to high yields. Not only simple 2-alkynyl benzyl azides 1a-j and their substituted analogues 1k-u and 6 but also heteroaromatic analogues, including pyridine 8, pyrroles 10a-c, furane 10d, and thiophenes 10e-g, gave the corresponding isoquinoline derivatives in excellent to allowable yields. Electron-donating and electron-accepting substituents on the aromatic ring were equally tolerated, and either acidic or basic (or even neutral) reaction conditions, depending on the reactivity of the substrate, could be applied to smoothly convert the azide starting materials into the desired isoquinoline products in moderate to good yields. Limits were found only in connection with the substituent at the alkyne terminus, where electron-neutral or electron-donating substituents are clearly favored. The iodine-mediated electrophilic cyclization of 1 most probably proceeds through the iodonium ion intermediate 4 followed by nucleophilic cyclization of the azide and subsequent elimination of N2. This new methodology was successfully applied to the short synthesis of norchelerythrine.
Studies of palladium-catalyzed coupling reactions for preparation of hindered 3-arylpyrroles relevant to (-)-rhazinilam and its analogues
Ghosez, Leon,Franc, Cecile,Denonne, Frederic,Cuisinier, Claire,Touillaux, Roland
, p. 1827 - 1839 (2007/10/03)
Suzuki cross-coupling reactions of 3-pyrroleboronic acid derivatives with haloaromatics and the reverse process i.e., the coupling of 3-iodo(bromo)pyrroles with arylboronic acids have been investigated as a potential key step in the synthesis of (-)-rhazinilam and analogues. It was found that 3-iodo-2-formyl-1-tosylpyrroles efficiently coupled with a variety of arylboronic acids in the presence of PdCl2(dppf) as catalyst. This catalytic system is compatible with a broad spectrum of arylboronic acids - electron-rich, electron-poor, hindered, heterocyclic - which easily coupled with the pyrrole substrate.
A new approach to the synthesis of N-protected 2- and 5-substituted 3-halopyrroles
Masquelin,Obrecht
, p. 276 - 284 (2007/10/02)
A new and efficient method for the preparation of N-protected 5- and 2-substituted 3-bromopyrroles 15 and 16 via acid-catalyzed cyclization of the corresponding acetylenic ketones 6 and acetylenic acetals 14 has been found (Scheme 3). Using this methodolo
