Intramolecular addition of acyl radicals to α-substituted vinylogous carbonates: demonstrating the effect of ring size on acyclic stereocontrolElectronic supplementary information (ESI) available: spectral data (IR, 1H and 13C NMR) and high resolution MS for 1/2a-c, 7–10. See http://www.rsc.org/suppdata/cc/b1/b106766b/

Evans, P. Andrew; Raina, Sushil; Ahsan, Khalid

doi:10.1039/b106766b

Cited by 20 publications

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“…For instance, while moderate diastereocontrol was observed in the formation of 180 (Scheme 108), higher selectivity was achieved in the formation of the corresponding pyran, while surprisingly five-membered ring formation gave the weakest stereochemical control of all. 218 Diazo-decompositions to give medium-ring ethers have focused mainly on O-H insertion and formation and rearrangement of oxonium ylides. More recently it has been shown that treatment of 181 with copper() hexafluoroacetylacetonate gives 182 chemoselectively.…”

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confidence: 99%

Saturated oxygen heterocycles

Elliott

2002

J. Chem. Soc., Perkin Trans. 1

143

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mentioning

confidence: 99%

Saturated oxygen heterocycles

Elliott

2002

J. Chem. Soc., Perkin Trans. 1

143

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Advances in Free Radical Reactions of Organoselenium and Organotellurium Compounds

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2011

Patai's Chemistry of Functional Groups

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Free radical reactions of organoselenium and tellurium compounds have been widely studied and exploited since the first two volumes of this series appeared. Alkyl aryl selenides and tellurides undergo alkyl C‐Se or C‐Te cleavage with stannanes or silanes to generate alkyl radicals that can be employed in reductions, allylations and both intermolecular and intramolecular additions to a large variety of unsaturated substrates, terminated by either hydrogen or arylchalcogen transfer. Selenoesters, telluroesters and related species generate acyl radicals that are useful in overall decarboxylations of carboxylic acids, and in addition and radical cyclization processes, including cascade reactions of polyenes to afford polycyclic products. Homolytic cleavage of diselenides and ditellurides produces selenyl and telluryl radicals that can be employed in additions to unsaturated acceptors, while the dichalcogenides themselves function as effective trapping agents for radicals produced in a variety of other ways, as from Barton thiohydroxamates. Selenols are efficient hydrogen donors that are of importance in kinetic studies of radical processes. When selenium and tellurium are joined to other heteroatoms, the resulting reagents effect radical 1,2‐additions to unsaturated substrates, as in the case of selenosulfonation and azidoselenenylation reactions. Other radical processes include oxidations, S H 2 substitutions, single electron transfers, extrusions and fragmentations, and reactions performed on solid supports. The synthetic utility of these processes, as well as mechanistic considerations are covered in this chapter.

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Iron‐Catalyzed Reductive Cyclization of Alkenyl Vinylogous Carbonates for Stereoselective Synthesis of Substituted Tetrahydrofurans, Tetrahydropyrans, and Chromans

2022

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A method for the stereoselective synthesis of substituted tetrahydrofurans (THFs), tetrahydropyrans (THPs), as well as chromans using intermolecular hydrogen atom transfer (HAT) followed by intramolecular radical cyclization of alkenyl vinylogous carbonates is described. This Fe(acac)3‐catalyzed reaction uses PhSiH3 as H‐source and works under ambient conditions in HFIP/ethylene glycol (5:1 mixture) as solvent. The methodology developed has broad substrate scope and is amenable to gram‐scale synthesis. The method gives ready access to even hexa‐substituted cyclic ethers containing two quaternary carbons. This strategy is used in the construction of oxaspirocyclic systems. Diastereoselective synthesis of fused bicyclic as well as tricyclic motifs could be achieved. The stereochemistry of the products was assigned using NOE experiments and was further confirmed by single‐crystal X‐ray diffraction studies on two derivatives.

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Abstract: The level of stereocontrol obtained in the reduction of the free radical derived from the intramolecular addition of an acyl radical to an alpha-branched vinylogous carbonate is dependent upon the ring-size of the cyclic ether.

Cited by 20 publications

References 16 publications

Saturated oxygen heterocycles

Saturated oxygen heterocycles

Advances in Free Radical Reactions of Organoselenium and Organotellurium Compounds

Iron‐Catalyzed Reductive Cyclization of Alkenyl Vinylogous Carbonates for Stereoselective Synthesis of Substituted Tetrahydrofurans, Tetrahydropyrans, and Chromans

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