Enantioselective and Regiodivergent Functionalization of<i>N-</i>Allylcarbamates by Mechanistically Divergent Multicatalysis
作者:Edward Richmond、Ismat Ullah Khan、Joseph Moran
DOI:10.1002/chem.201602792
日期:2016.8.22
A pair of mechanistically divergent multicatalytic reaction sequences has been developed consisting of nickel‐catalyzed isomerization of N‐allylcarbamates and subsequent phosphoric‐acid‐catalyzed enantioselective functionalization of the resulting intermediates. By appropriate selection of reaction partners, in situ generated imines and ene‐carbamates are mechanistically partitioned to yield opposing
cycloaddition of β-substituted ene- and thioenecarbamates as well as cyclic enamides with quinone diimides catalyzed by a BINOL- and SPINOL-derived phosphoric acid is reported. A wide variety of 2,3-disubstituted 2-aminoindolines, including polycyclic ones, were prepared in generally high yields (up to 98%) with moderate to complete diastereoselectivities and in most cases excellent enantioselectivities
the oxysulfonylated products in moderate to excellent yields. Moreover, the direct incorporation of sulfurdioxide into the sulfonylated products via organolithium chemistry has been achieved. The formed N-O-acetals are competent acylimine precursors. Their utilization as building blocks for the synthesis of biologically relevant β-amidosulfones is described as well.
<i>N</i>,<i>N′</i>-Dioxide/Nickel(II)-Catalyzed Asymmetric Inverse-Electron-Demand Hetero-Diels-Alder Reaction of β,γ-Unsaturated α-Ketoesters with Enecarbamates
have been developed to catalyze the inverse‐electron‐demandhetero‐Diels–Alderreaction of β,γ‐unsaturated α‐ketoesters with acyclic enecarbamates. After detailed screening of the reaction parameters, mild optimized reaction conditions were established, affording 3,4‐dihydro‐2H‐pyranamines in up to 99 % yield, 99 % ee and more than 95:5 d.r. The catalytic system was also efficient for β‐substituted acyclic
reaction of anilines and phenylacetaldehydes in the presence of chiral phosphoric acid afforded optically active 1,2-trans, 2,3-cis 1,3-diaminotetralins in high yields with excellent diastereo- and enantioselectivities. The trans/cis product was readily isomerized to a trans/trans stereoisomer with no significant loss of enantiomeric purity.