Remarkable contrast between chemospecificities in acid-mediated arylation of δ- and γ-ketocarboxylic acids was revealed: in the presence of P2O5–MsOH, TfOH, PPA, and MsOH, arylation of δ-ketocarboxylic acid 1A with arenes takes place at the carboxycarbonyl carbon, while that of γ-ketocarboxylic acid 1B takes place at the ketone carbonyl carbon, specifically.
Copper‐Catalyzed Formal [2+2+1] Heteroannulation of Alkenes, Alkylnitriles, and Water: Method Development and Application to a Total Synthesis of (±)‐Sacidumlignan D
作者:Tu M. Ha、Claire Chatalova‐Sazepin、Qian Wang、Jieping Zhu
DOI:10.1002/anie.201604528
日期:2016.8
A copper‐catalyzed three‐component reaction of alkenes, alkylnitriles, and water affords γ‐butyrolactones in good yields. The domino process involves an unprecedented hydroxy‐cyanoalkylation of alkenes and subsequent lactonization with the creation of three chemical bonds and a quaternary carbon center. The synthetic potential of this novel [2+2+1] heteroannulation reaction was illustrated by a concise
ZnI<sub>2</sub>/Zn(OTf)<sub>2</sub>-TsOH: a versatile combined-acid system for catalytic intramolecular hydrofunctionalization and polyene cyclization
作者:Ting-Hung Chou、Bo-Hung Yu、Rong-Jie Chein
DOI:10.1039/c9cc07242j
日期:——
combined-acid system using a zinc(II) salt [ZnI2 or Zn(OTf)2] and p-toluene sulfonic acid (TsOH) was investigated for catalytic cationic cyclizations, including intramolecular hydrocarboxylation, hydroalkoxylation, hydroamination, hydroamidation, hydroarylation and polyenecyclizations. This reaction provides easy access to five- and six-membered O- and N-containing saturated heterocyclic compounds, tetrahydronaphthalene
A newsynthesis of γ-lactones by peroxydisulfate oxidation of isopropylbenzenes is described. Evidence concerning the free-radical mechanism is reported; the intermediate formation of alkyl and benzyl radicals is evidenced by trapping them with quinoxaline. The role of the iron catalyst is discussed.
present our studies on the solvent-controlled difunctionalization of alkenes utilizing chlorodifluoroacetic acid (CDFA) and α-halo carboxylicacids for the synthesis of γ-lactones, γ-lactams and α,α-difluoroesters. Mechanistic insights revealed that photocatalytic reductive mesolytic cleavage of the C–X bond delivers elusive α-carboxyl alkyl radicals. In the presence of an olefin molecule, this species