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: The unprecedented annulation reaction successfully facilitated the construction of sp(3) -rich and highly substituted 3,2'-pyrrolidinyl spirooxindoles supporting many chiral centers.
Abstract: Catalytic addition of chiral phosphine, that is, (R)- or (S)-SITCP, to an α-substituted allene ester generated a zwitterionic dipole. Under optimized reaction conditions, this dipole could engage isatine-derived N-Boc-ketimines in a novel mode of [3+2] annulation reaction. Pyrrolinyl spirooxindoles are thus afforded in high yields and with excellent enantioselectivities. The unprecedented annulation reaction successfully facilitated the construction of sp(3) -rich and highly substituted 3,2'-pyrrolidinyl spirooxindoles supporting many chiral centers.
95 citations
TL;DR: All pyrido[1,2-a]benzimidazoles, polysubstituted benzenes, poly SubStituted indoles, and some key reaction intermediates are characterized by (1)H and (13)C NMR, MS, IR spectra, and elemental analysis as well as X-ray crystallography.
Abstract: Polysubstituted pyrido[1,2-a]benzimidazole derivatives are efficiently produced in moderate yields in a novel one-pot, four-component reaction from pyridine or 3-picoline, chloroacetonitrile, malononitrile, and aromatic aldehyde in refluxing acetonitrile. The mechanism of this novel reaction was believed involving the formation of polysubstituted benzenes with subsequent substitution and annulation reaction of pyridine. All pyrido[1,2-a]benzimidazoles, polysubstituted benzenes, polysubstituted indoles, and some key reaction intermediates are characterized by 1H and 13C NMR, MS, IR spectra, and elemental analysis as well as X-ray crystallography.
95 citations
TL;DR: This method features inexpensive catalysts, no need for extra oxidant, and high step-enconomy, which make it pratical and attractive.
Abstract: A concise copper-catalyzed N–O bond cleavage/C–C/C–N bond formation procedure has been described for the synthesis of multisubstituted pyridines. Various oxime acetates, activated methylene compounds, and a wide range of aldehydes bearing aryl, heteroaryl, vinyl, and trifluoromethyl groups were employed to provide the tri- or tetrasubstituted pyridines with flexible substitution patterns. Moreover, this method features inexpensive catalysts, no need for extra oxidant, and high step-enconomy, which make it pratical and attractive.
95 citations
TL;DR: In this article, it was shown that the intermediacy of iminyl radicals in the rearrangements of the spirocyclohexadienyls obtained by 3 + 2 annulation between imidoyl radicals and alkynes can be demonstrated.
95 citations
TL;DR: A novel and selective palladium-catalyzed carbonylative annulation process for the synthesis of 3-(halomethylene)indolin-2-ones was demonstrated and selectively obtained from the carbonyLative annulations of 2-(1-alkynyl)benzenamines with CO in moderate to good yields.
94 citations