Access to Indoles via Diels-Alder Reactions of 5-Methylthio-2-vinylpyrroles with Maleimides

Abstract

in Wiley InterScience (www.interscience.wiley.com).Variously substituted 2-vinylpyrroles underwent an endo-addition [4þ2] cycloaddition reaction with maleimides followed by a spontaneous highly diastereoselective (93-98% de) isomerization to give tetrahydroindoles in moderate to excellent yield. Treatment with activated MnO 2 in refluxing toluene provided the corresponding indoles in moderate to good yield. This highly convergent methodology for formation of indoles is versatile and the starting materials are conveniently prepared.

Crystal structure of (1S,2R,6R,7R,8S,12S)-4,10,17-triphenyl-15-thia-4,10-diazapentacyclo[5.5.5.01,16.02,6.08,12]heptadeca-13,16-diene-3,5,9,11-tetronep-xylene hemisolvate

“…Reported heterocycles include indole, pyrrole (Le Strat et al, 2005;Noland et al, 2013), furan (Brewer et al, 1971;Brewer & Elix, 1975b;Davidson & Elix, 1970), benzofuran, and benzothiophene (Marrocchi et al, 2001;Pihera et al, 1999). A DielsAlder reaction was attempted between 2-(-styryl)thiophene (1) (Tasch et al, 2013) and N-phenylmaleimide (2) in an effort to expand this methodology (Fig.…”

Electrooxidation Is a Promising Approach to Functionalization of Pyrazole-Type Compounds

“…Thiocyanation of the C–H bond of arenes is an effective tool for C–S coupling [ 81 , 82 , 83 , 84 ]. The resulting aryl thiocyanates are valuable precursors of sulfur and nitrogen-containing compounds (thiols [ 85 ], (di)sulfides [ 86 , 87 ], dithiocarbamates [ 88 ], thiazoles [ 89 ], tetrazoles [ 90 ]), and are highly bioactive compounds (antifungal [ 91 ], antitumor [ 92 ], antiparasitic [ 93 ]). Recently synthesized thiocyanates of pyrazole derivatives also have sufficient antifungal [ 94 ] and antitumor [ 95 ] activity.…”

Highly selective Diels–Alder and Heck arylation reactions in a divergent synthesis of isoindolo- and pyrrolo-fused polycyclic indoles from 2-formylpyrrole

“…On the other hand, the formation of pyrrolo [3,4-e]indoles 9/10 can be achieved via a Diels-Alder cyloaddition of 2-vinylpyrroles 8 with maleimides 7 [31][32][33][34][35]. This is a representative example of the less common approach for the construction of the indole skeleton on substituted pyrroles by generating the benzene ring via an annulation process [36][37][38][39].…”