Highly Selective Catalyst-Directed Pathways to Dihydropyrroles from Vinyldiazoacetates and Imines

Abstract

Copper-catalyzed reactions of vinyldiazoacetates with imines occur via a pathway in which the activated imine undergoes electrophilic addition to the vinyldiazo compound, whereas reactions catalyzed by rhodium(II) proceed through a metal carbene to an intermediate iminiumylide. Both pathways exhibit high stereoselectivities.

Recent applications of the divinylcyclopropane–cycloheptadiene rearrangement in organic synthesis

“…The cis -divinylaziridine rearrangement ( 311 to 312 , see Scheme 38) after rhodium-catalyzed aziridine formation between vinyl-diazo compound 317 and imine 318 has been found by Doyle [224–226]. Rearrangement occurred smoothly to give desired dihydroazepine 320 .…”

Cycloaddition reactions of enoldiazo compounds

“…Under similar reaction conditions, divergent products can be obtained from identical reactants solely controlled by different catalysts. 178–180 In previous studies, α-diazocarbonyl compounds, such as α-hydro-, 181 α-alkyl-, 182 α-vinyl-, 183,184 and α-aryl-α-diazoacetates, 185 have proven to be versatile reagents in several catalyst-dependent processes. The controllable versatility of enoldiazo compounds (catalyst-controlled switchable chemoselectivity) in cycloaddition reactions is discussed in this section.…”

Katalytische selektive Synthese

“…[147] In diesem Fall wird zur Erklärung der Selektivität eine mechanistische Divergenz geltend gemacht, und zwar zwischem dem sAllyl-Eisenkomplex 143, [148] der zu 144 mit einem sperrigen (tBu) 38 b). [152] In diesem Fall folgt der Bildung eines RhCarbenoid der Angriff des Iminstickstoffs, der zu 151 führt, während Aktivierung des Imins mit Lewis-Säure nucleophile Addition des Diazo-Zentrums bevorzugt und sich letztendlich ein regioisomeres Produkt 152 bildet.…”