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Intramolecular reaction
About: Intramolecular reaction is a research topic. Over the lifetime, 5015 publications have been published within this topic receiving 138213 citations.
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TL;DR: Various phenylsulfonyl allene derivatives were prepared with double bonds tethered either to the alpha-position or the gamma-position of the allene, resulting in highly regio- and stereospecific thermal [2 + 2]-cycloaddition across the nonactivated cumulene double bond.
Abstract: Various phenylsulfonyl allene derivatives were prepared with double bonds tethered either to the α-position or the γ-position of the allene. These substrates underwent a highly regio- and stereospecific thermal [2 + 2]-cycloaddition across the nonactivated cumulene double bond, forming distal cycloadducts (i.e., 57) in the case of α-tethered allenes and proximal adducts (i.e., 25) in the case of γ-tethered allenes. The mechanistic rationale for the observed stereospecificity involves initial diradical formation, followed by a rapid ring closure to the more stable cis-fused ring system. The tether may be equipped with heteroatoms, allowing for the formation of fused heterocycles (e.g., 61), and the cycloaddition can be facilitated by the introduction of sterically bulky groups and/or by conformational rigidity to the tether. Other modes of cyclization were observed in the presence of sodium benzenesulfinate or Lewis acids, in which cases polar mechanisms prevail. The chemoselectivity is reversed for [4 + 2...
60 citations
TL;DR: Cobalt carbonyl complexes of electron-deficient internal alkynes undergo Pauson-Khand cycloaddition efficiently and regioselectively as mentioned in this paper.
Abstract: Cobalt carbonyl complexes of electron-deficient internal alkynes undergo Pauson-Khand cycloaddition efficiently and regioselectively
60 citations
TL;DR: The A-ring fragment of the gambieric acids has been prepared by a short and efficient route and the key 3(2H)-furanone intermediate has been obtained by [2,3] rearrangement of an allylic oxonium ylide generated from intramolecular reaction of a crotyl ether with a copper carbenoid.
60 citations
60 citations
TL;DR: Aldoximes and ketoximes containing two alkenyl moieties in different side chains undergo thermal conversion to 5 - and 6 - membered cyclic nitrones, via concerted 1,3 -azaprotio cyclotransfer, followed by stereospecific intramolecular cycloaddition to give tricyclic spiro- and fused-ring systems as discussed by the authors.
60 citations