47 research outputs found
Rhodium-Catalyzed Intermolecular [2 + 2] Cycloaddition of Terminal Alkynes with Electron-Deficient Alkenes
The first catalytic intermolecular [2 + 2] cycloaddition of terminal alkynes with electron-deficient alkenes is reported. The reaction proceeds with an 8-quinolinolato rhodium/phosphine catalyst system to give cyclobutenes from various substrates having polar functional groups in high yields with complete regioselectivity
Synthesis and Reactivity of Phosphine-Quinolinolato Rhodium Complexes: Intermediacy of Vinylidene and (Amino)carbene Complexes in the Catalytic Hydroamination of Terminal Alkynes
We report here on the syntheses of
rhodium(I) complexes bearing a phosphine-quinolinolate ligand and
the isolation of two classes of important intermediates in the anti-Markovnikov
hydroamination of terminal alkynes with secondary amines: vinylidene-bridged
dirhodium complexes and (amino)carbene complexes. We first prepared
various rhodium(I) complexes bearing a phosphine-quinolinolate ligand
and found that some of these complexes had catalytic activity for
the anti<i>-</i>Markovnikov hydroamination of terminal alkynes
with secondary amines. The reaction of stoichiometric amounts of a
(PNO)Rh complex with terminal alkynes provided vinylidene-bridged
dirhodium complexes. When the resulting vinylidene complexes were
reacted with secondary amines, (amino)carbene complexes were generated,
which gave the hydroamination product upon heating with an additive.
These results suggest that this anti-Markovnikov hydroamination catalyzed
by (PNO)Rh complexes proceeds via vinylidene and (amino)carbene complexes
Synthesis and Reactivity of Phosphine-Quinolinolato Rhodium Complexes: Intermediacy of Vinylidene and (Amino)carbene Complexes in the Catalytic Hydroamination of Terminal Alkynes
We report here on the syntheses of
rhodium(I) complexes bearing a phosphine-quinolinolate ligand and
the isolation of two classes of important intermediates in the anti-Markovnikov
hydroamination of terminal alkynes with secondary amines: vinylidene-bridged
dirhodium complexes and (amino)carbene complexes. We first prepared
various rhodium(I) complexes bearing a phosphine-quinolinolate ligand
and found that some of these complexes had catalytic activity for
the anti<i>-</i>Markovnikov hydroamination of terminal alkynes
with secondary amines. The reaction of stoichiometric amounts of a
(PNO)Rh complex with terminal alkynes provided vinylidene-bridged
dirhodium complexes. When the resulting vinylidene complexes were
reacted with secondary amines, (amino)carbene complexes were generated,
which gave the hydroamination product upon heating with an additive.
These results suggest that this anti-Markovnikov hydroamination catalyzed
by (PNO)Rh complexes proceeds via vinylidene and (amino)carbene complexes