Copper-Catalyzed Ficini [2 + 2] Cycloaddition of Ynamides
作者:Hongyan Li、Richard P. Hsung、Kyle A. DeKorver、Yonggang Wei
DOI:10.1021/ol101418d
日期:2010.9.3
The Ficini [2 + 2] cycloaddition using N-sulfonyl-substituted ynamides is described, featuring the utility of CuCl2 and AgSbF6 as catalysts. This work represents the first successful example of ynamides participating in a thermal [2 + 2] cycloaddition with enones.
A TMSOTf-catalyzed hydroalkoxylation of ynesulfonamides with esters is described for the efficient synthesis of alkoxy-substituted enamides with high stereoselectivity.
We present a metal-free [2 + 2 + 2] cycloaddition of ynamides with nitriles that enables highly efficient access to 2,4-diaminopyridines. This catalytic protocol is more environmentally friendly and allows for a concomitant construction of C–C and C–N bonds between ynamides and nitriles, exhibiting excellent chemoselectivity, regioselectivity, and wide functional groups tolerance.
A metal-free [2 + 2 + 2] cycloaddition of alkyne-cyanamides or ynamide-nitriles with ynamides is described for the efficient synthesis of amino-substituted α- and δ-carbolines. This novel methodology is environmentally friendly and allows for highly regioselective access to carboline derivatives in good to excellent yields with wide functional group tolerance.
substituted ynamides with o-quinone methides is reported. In the presence of AlCl3, a sequence comprising a [2 + 2] cycloaddition followed by the torquoselective 4π-electrocyclic ring opening and 6π-electrocyclic ring closure leads to highly stereoselective formation of diastereoisomeric 4-amino-2H-chromenes. Terminally unsubstituted ynamides undergo AlCl3-catalyzed [4 + 2] cycloaddition with o-quinone