Copper-Catalyzed Reaction of Terminal Alkynes with Nitrones. Selective Synthesis of 1-Aza-1-buten-3-yne and 2-Azetidinone Derivatives
摘要:
Reaction of arylacetylenes with C,N-diarylnitrones using a catalyst system of CuI-dppe (dppe = 1,2-bis(diphenylphosphino)ethane) in the presence of potassium carbonate in DMF predominantly affords the corresponding 1,2,4-triaryl-1-aza- 1-buten-3-ynes in good yields. In contrast, the catalytic reaction using CuI in the presence of an excess amount of pyridine as the ligand gives 1,3,4-triaryl-2-azetidinones as the major products. The reaction with aliphatic terminal alkynes in place of arylacetylenes produces the latter products irrespective of the catalyst system used. Asymmetric induction is also observed in the reaction of phenylacetylene with alpha,N-diphenylnitrone to give 1,2,4-triphenyl-2-azetidinone in the presence of chiral bisoxazoline-type ligands.
cyclization of alkynylimines and double isocyanides is described. This facile procedure is efficient for synthesizing various 4-amidyl-2-aminopyrroles. Mechanism investigation indicates that a four-membered ring-fused pyrrole species is a key intermediate and the reaction involves [4 + 1] cycloaddition, protonation, nucleophilic addition, 1,4-addition of isocyanide, and rearomatization. Interestingly,
We report an electrophiliccyclization of alkynyl imines to afford polysubstituted 3-haloquinolines using CuX-activated N-halosuccinimdes (NXS) as electrophiles. Control experiments demonstrated that the NXS/CuX system might be more active than single NXS and could be applied in the electrophiliccyclization of electron- deficient substrates.
Abstract Generation of multi-substituted pyrroles is accomplished through an unexpected iron(II)-promoted reaction of N-arylprop-2-yn-1-imines with water. This transformation proceeds smoothly with excellent chemoselectivity and regioselectivity. A stoichiometric amount of Fe(OTf)2 is necessary for the successful conversion. A Lewis acid-promoted tandem reaction pathway is proposed.
Rh(III)-catalyzed double molecular alkyne imine C–H activation: a facile and efficient synthesis of functionalized acridine compounds
作者:Yingying Shan、Weidong Yan
DOI:10.1016/j.tetlet.2016.05.077
日期:2016.6
The construction of a new nitrogen heterocyclic ring via the C–H activation is a facile and efficient protocol to afford polysubstituted acridine compounds from simple, readily available starting materials. In this Letter, functionalized benzo[c]acridine and thieno[3,2-c]acridine compounds have been accomplished by the method of Rh(III)-catalyzed double molecular alkyne imine C–H activation.