Formation of fused tricyclic azetidinones and pyrrolidinones by intramolecular SH2 processes

Beckwith, A. L. J.; Boate, D. R.

doi:10.1021/jo00253a028

Cited by 46 publications

(9 citation statements)

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“…13 In addition, 12 displayed signals at  4.15 (J = 18 Hz) and  4.79 (J = 18 Hz) in its 1 H NMR spectrum assigned to the non-equivalent benzylic protons, and at  5.10 for the C-4 proton. These values are in good agreement with those reported by Beckwith and Boate for the closely-related sulfur analogue (14) Further reaction of (11, R = H) with N-hydroxypyridine-2-thione in the presence of dicyclohexylcarbodiimide (DCC) afforded the pyridinethioneoxycarbonyl (PTOC, Barton) 15 ester free radical precursor (15) (Scheme 3). The Barton ester proved to be quite labile and was not purified.…”

Section: Radical Routes To Optically-active Selenium Analogues Of -L...supporting

confidence: 88%

“…Our alternative approach to these classes of compound began with the previously reported 3,3-dichloro-2,2-dimethylpropionyl chloride 17 (30) which was converted firstly into the corresponding benzylseleno amide (31) by reaction with 2-benzylselenoaniline and then into the chloroazetidinone (32) following the general procedure reported by Beckwith and Boate. 14 To our surprise, treatment of chloride (32) with one equivalent of sodium iodide in acetone did not provide the expected iodide, rather, the ring-closed selenapenem nucleus, 2,2a-dihydro-2,2-dimethyl-1H-azeto[2,1-b]benzoselenazol-1-one (33) was obtained in 46% isolated yield (Scheme 7). † Scheme 7 † This transformation is catalytic in sodium iodide.…”

Section: Intramolecular Nucleophilic Chemistry: Formation Of Benzofus...mentioning

confidence: 98%

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Preparation of novel selenapenams and selenacephems by nucleophilic and radical chemistry involving benzyl selenides

Carland¹,

Martin²,

Schiesser³

2004

Org. Biomol. Chem.

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2,2a-Dihydro-1H,8H-azeto[2,1-b][1,3]benzoselenazin-1-one (12), 5-selena-1-azabicyclo[4.2.0]oct-3-en-8-one (13), ethyl 1-aza-7-oxo-4-selenabicyclo[3.2.0]heptane-2-carboxylate (16), and benzoselenopenem (33) can be prepared in 39-85% yield through the intramolecular homolytic substitution of aryl, vinyl or alkyl radicals at the selenium atom in suitably-substituted 4-benzylseleno-beta-lactams, or through intramolecular nucleophilic substitution by the benzylseleno moiety in 4-halo-beta-lactam precursors. Application of this chemistry to the preparation of optically active selenium-containing analogues of beta-lactam antibiotics is also detailed.

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Section: Radical Routes To Optically-active Selenium Analogues Of -L...supporting

confidence: 88%

Section: Intramolecular Nucleophilic Chemistry: Formation Of Benzofus...mentioning

confidence: 98%

Preparation of novel selenapenams and selenacephems by nucleophilic and radical chemistry involving benzyl selenides

Carland¹,

Martin²,

Schiesser³

2004

Org. Biomol. Chem.

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“…Since the minor product has been isolated by us by the linear thiocyclization of an N-acyliminium ion, [2,4] and by others by radical cyclization with Bu 3 SnH as a promoter, [14] a chemical separation protocol was envisioned, as reported by us for the related thiolactams. [4] Thus, oxidation of the mixture of 25 and 26 with 2.2 equiv.…”

Section: Role Of the N-acyliminium Aromaticity On The Cyclization Reamentioning

confidence: 99%

Exocyclic–Endocyclic N‐Acyliminium Ion Equilibration via an Intramolecular α‐Thioamidoalkylation in the Synthesis of Fused N,S‐Heterocyclic Systems: Some New Parameters

et al. 2005

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The reactivity of N‐[aryl(or alkyl)thio(oxo or seleno)alkylamidals 6 bearing the N‐(CH2)n‐X‐(CH2)m‐Ar functionality towards neat TFA has been examined. Substrates of type 6 give, together with the products 11, 17, 19, and 25 of the “expected” π‐cyclization process, the “unexpected” products 12, 18, and 26 resulting from a new tandem heteroamidoalkylation/isomerization/π‐cyclization. The composition of the final isomeric mixture depends on the temperature of the reaction, with a high selectivity in favor of the “expected” π‐cyclization product 11 as a thermodynamic isomer. Furthermore, the results demonstrate again the relevance of TFA catalysis and support two reaction pathways involving the formation of an aza‐sulfonium cation A as a valuable intermediate which undergoes the π‐cyclization process alone or in tandem with the thiocyclization/isomerization to give the cyclized products cited above. For the latter tandem reaction, we have established clearly that the n value should be equal to 1, the process can be performed independently for both the succinimide and phthalimide series, the reaction depends on the nucleophilicity of the heteroatom, and can be generalized to other heterocycles. Only the role of the benzene substitution has still to be totally elucidated. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

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“…[10,11] Sulfur is particularly wellsuited, and several reactions have been reported that employ homolytic substitution on this particular atom. A variety of different functions have been introduced (sulfides, [12][13][14] disulfides, [15] thioesters, [16][17][18] and sulfoxides; [14,19,20] sulfones seem not to be prone to such processes [14,21] ), but so far none in which an additional heteroatom was present in the ring next to the sulfur atom, despite the increased potential offered by the heterocyclic adducts.…”

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confidence: 99%

Formation of Cyclic Sulfinates and Sulfinamides through Homolytic Substitution at the Sulfur Atom

et al. 2006

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Ring road: Cyclic sulfinates and sulfinamides can be synthesized by homolytic substitution to give alkyl and benzofused families of compounds. The presence of an additional heteroatom in the ring allows the preparation of sulfur‐based heterocycles that are useful synthetic intermediates (see scheme). The stereogenic sulfur atom transfers its chirality to prochiral radicals. TTMSS=tris(trimethylsilyl)silane, AIBN=azobisisobutyronitrile.

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Formation of fused tricyclic azetidinones and pyrrolidinones by intramolecular SH2 processes

Cited by 46 publications

References 1 publication

Preparation of novel selenapenams and selenacephems by nucleophilic and radical chemistry involving benzyl selenides

Preparation of novel selenapenams and selenacephems by nucleophilic and radical chemistry involving benzyl selenides

Exocyclic–Endocyclic N‐Acyliminium Ion Equilibration via an Intramolecular α‐Thioamidoalkylation in the Synthesis of Fused N,S‐Heterocyclic Systems: Some New Parameters

Formation of Cyclic Sulfinates and Sulfinamides through Homolytic Substitution at the Sulfur Atom

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