Ap alladium-catalyzed cascade reaction has been realized for the synthesis of 5H-pyrrolo[2,3b]pyrazines and 5H-pyrazino[2,3-b]indoles from benzyli socyanide by choosing o-pivaloyloximes or oiodoanilines as as uitable substrate.T he key steps involveda re (i)o xidative addition of palladium throughN -O or C-Ic leavage; (ii)m igratory double isocyanide insertion;a nd (iii)c ross-dehydrogenative coupling. Notable features are good functional group tolerance as well as formation of three C-C and one C-N bonds. Scheme 2. Scope and limitations of oximes with isocyanides. Reaction conditions: 1a-v (0.5 mmol), 2a--c (1.05 mmol), Pd(PPh 3 ) 4 (5.0 mol%), DBU (1.1 mmol) and toluene( 0.5 M) were stirred at reflux for the indicated time unless otherwise noted.Y ields of isolated products reported;trace refers to no product isolation. Scheme 5. Plausible reaction mechanismfor 5H-pyrrolo[2,3-b]pyrazines.
Versatile role of λ3‐iodanes has been identified between the reaction of hydroquinone and β‐enaminones for the synthesis of 5‐acyloxy‐4‐hydroxy indoles. The reaction is proposed to proceed through an intermolecular C−C bond formation, intramolecular cyclization, acyloxylation and 1,4‐acyl migration. The important features of this work include various acyloxylation from λ3‐iodanes and broad functional group tolerance to deliver 34 examples in moderate to good yields.magnified image
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.