The first N-heterocyclic carbene-catalyzed stereoselective aza-Michael-Michael-lactonization cascade reaction of 2'-aminophenylenones and 2-bromoenals for the construction of chiral functionalized tetrahydroquinolines with three consecutive stereogenic centers has been achieved in high yields (up to 98%) with excellent diastereo- (>25:1) and enantioselectivities (up to 98.7% ee).
We
developed an efficient visible-light-mediated formal carbene
insertion reaction of 1,3-diketones with diazoesters for the construction
of enantioenriched 1,4-dicarbonyl compounds with a quaternary carbon
center. Combining visible light and a Brønsted acid catalyst,
chiral 1,4-dicarbonyl compounds were achieved in good yields with
high enantioselectivities by a photochemical carbene transfer protocol.
An efficiently stereoselective
[4 + 2] cycloaddition of 3-alkylenyloxindoles
and α-diazoketones through sequential visible-light photoactivation
and N-heterocyclic carbene catalysis was achieved.
A series of tetrahydropyrano[2,3-b]indoles with an
all-carbon quaternary stereocenter were obtained in good yields with
excellent diastereo- and enantioselectivities.
Novel and highly efficient cross couplings of aryl bromides and chlorides with AlAr3(THF) (Ar = Ph, 2,4,6-Me3C6H2, 2-naphthyl or 4-Me3SiC6H4) catalyzed by the economic palladium catalyst of PCy3 are reported without the use of a base and under mild reaction conditions at room temperature or temperatures < or = 60 degrees C even for couplings of bulky aryl halides and the Al(2,4,6-Me3C6H2)3(THF) reagent.
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