Asymmetric Synthesis of Spirocyclic Oxindole δ-Lactams via NHC-Catalyzed Formal [2+4] Annulation of Aliphatic Aldehydes with Oxindole-Derived α,β-Unsaturated Ketimines
An N-heterocyclic carbene (NHC)-catalyzed formal [2+4] annulation reaction of aliphatic aldehydes with oxindole-derived α,β-unsaturated ketimines under oxidative conditions is reported, affording spirocyclic oxindole δ-lactams with good yields, moderate diastereoselectivies, and good to excellent enantioselectivies. This reaction can be readily carried out on a gram scale, and the products could be
Regio- and diastereoselective construction of 1′,2′-(dihydrospiro[indoline-3,3′-pyrrol]-2′-yl)acrylates through phosphine-catalyzed [4 + 1] annulation of Morita–Baylis–Hillman carbonates with oxindole-derived α,β-unsaturated imines
作者:Yu Lei、Xiao-Nan Zhang、Xue-Yan Yang、Qin Xu、Min Shi
DOI:10.1039/c5ra09147k
日期:——
Phosphine-catalyzed [4 + 1] annulation of Morita–Baylis–Hillman (MBH) carbonates with oxindole-derived α,β-unsaturated imines has been developed, giving the corresponding 1′,2′-(dihydrospiro[indoline-3,3′-pyrrol]-2′-yl)acrylates in moderate to good yields and diastereoselectivities under mild conditions.
NHC-Catalyzed Ester Activation: Access to Sterically Congested Spirocyclic Oxindoles via Reaction of α-Aryl Esters and Unsaturated Imines
作者:Yonggui Chi、Lin Hao、Chan Chuen、Rakesh Ganguly
DOI:10.1055/s-0033-1338945
日期:——
asymmetric catalytic activation of esters should provide useful strategies for organic synthesis. Here we report a N-heterocyclic carbene (NHC)-mediated reaction of α-aryl acetic esters with oxindole-derived α,β-unsaturated imines. The reaction involves the formation of NHC-bound ester enolate intermediatefrom an ester as a key step, and furnishes spirocyclic oxindole products. The sterically congested