Topic
Annulation
About: Annulation is a research topic. Over the lifetime, 10152 publications have been published within this topic receiving 189701 citations.
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TL;DR: A rhodium-catalyzed annulation between ethyl benzimidates and α- aroyl sulfur ylides was developed, affording a series of pyrano[4,3,2-ij]isoquinoline derivatives in moderate to good yields with good functional group compatibility.
108 citations
TL;DR: An annulation reaction proceeding by the intermolecular addition of an arylpalladium(II) halide across a strained alkene, followed by an intramolecular C-H functionalization of a pendant heterocycle is described.
108 citations
TL;DR: Tricyclic indolines were obtained by the present new intramolecular [3+2] annulation between a vinyl group and an aniline moiety using Selectfluor as oxidant.
Abstract: Tricyclic indolines are obtained by the present new intramolecular [3+2] annulation between a vinyl group and an aniline moiety using Selectfluor as oxidant.
108 citations
TL;DR: A series of enantiomerically enriched tropanes was synthesized by the rhodium(II) octanoate-catalyzed reaction of various N-BOC-protected pyrroles with vinyldiazomethanes as mentioned in this paper.
Abstract: A series of enantiomerically enriched tropanes was synthesized by the rhodium(II) octanoate-catalyzed reaction of various N-BOC-protected pyrroles with vinyldiazomethanes. The overall 3 + 4 annulation occurs by a tandem cyclopropanation/Cope rearrangement. Asymmetric induction was best achieved in these transformations by using either (S)-lactate or (R)-pantolactone as a chiral auxiliary on the vinyldiazomethanes. Reactions carried out with the chiral catalyst tetrakis[N-(4-tert-butylbenzenesulfonyl)-(L)-prolinato]dirhodium (2) provided moderate asymmetric induction, but also resulted in the formation of isomeric azabicyclooctane side products. The utility of the synthetic process was demonstrated through the asymmetric synthesis of (−)-anhydroecgonine methyl ester and (−)-ferruginine.
108 citations
TL;DR: This two-step ring-forming sequence involved initial generation of the benzyl enamine through either a condensation or conjugate addition reaction with BnNH 2 , followed by aza-annulation with acryloyl chloride or acrylic anhydride.
Abstract: The aza-annulation of β-enamino carbonyl substrates with acrylate derivatives provides an efficient and convenient route for the regioselective construction of δ-lactams. This two-step ring-forming sequence involved initial generation of the benzyl enamine through either a condensation or conjugate addition reaction with BnNH 2 , followed by aza-annulation with acryloyl chloride or acrylic anhydride. Controlled by the rigid framework of the intermediate lactam, introduction of ring substituents was accomplished with high relative stereoselectivity. The carbonyl functionality, which was necessary to direct the regioselectivity of the aza-annulation reaction, was then transformed into a protected hydroxyl substituent through Baeyer-Villiger oxidation. The resultant δ-lactam product was used as a valuable intermediate in the synthesis of three natural products. Subsequent modification of this δ-lactam gave the naturally occuring α-mannosidase inhibitors (±)-mannonolactam and (±)-deoxymannojirimycin, while synthesis of the alkaloid (±)-prosopinine was accomplished through homologation of the lactam carbonyl
108 citations