14 research outputs found
Gold-Catalyzed Cycloisomerization of 1,7-Diyne Benzoates to Indeno[1,2-<i>c</i>]azepines and Azabicyclo[4.2.0]octa-1(8),5-dines
No full textA synthetic method that relies on Au(I)-catalyzed cycloisomerization
reactions of 1,7-diyne benzoates to prepare indeno[1,2-<i>c</i>]azepines and azabicyclo[4.2.0]octa-1(8),5-dines is described
Gold-Catalyzed Cycloisomerization of 1,7-Diyne Benzoates to Indeno[1,2-<i>c</i>]azepines and Azabicyclo[4.2.0]octa-1(8),5-dines
No full textA synthetic method that relies on Au(I)-catalyzed cycloisomerization
reactions of 1,7-diyne benzoates to prepare indeno[1,2-<i>c</i>]azepines and azabicyclo[4.2.0]octa-1(8),5-dines is described
Gold-Catalyzed Cycloisomerization of 1,7-Diyne Benzoates to Indeno[1,2-<i>c</i>]azepines and Azabicyclo[4.2.0]octa-1(8),5-dines
No full textA synthetic method that relies on Au(I)-catalyzed cycloisomerization
reactions of 1,7-diyne benzoates to prepare indeno[1,2-<i>c</i>]azepines and azabicyclo[4.2.0]octa-1(8),5-dines is described
Gold-Catalyzed Cycloisomerization of 1,7-Diyne Benzoates to Indeno[1,2-<i>c</i>]azepines and Azabicyclo[4.2.0]octa-1(8),5-dines
No full textA synthetic method that relies on Au(I)-catalyzed cycloisomerization
reactions of 1,7-diyne benzoates to prepare indeno[1,2-<i>c</i>]azepines and azabicyclo[4.2.0]octa-1(8),5-dines is described
Gold-Catalyzed Cycloisomerization of 1,7-Diyne Benzoates to Indeno[1,2-<i>c</i>]azepines and Azabicyclo[4.2.0]octa-1(8),5-dines
No full textA synthetic method that relies on Au(I)-catalyzed cycloisomerization
reactions of 1,7-diyne benzoates to prepare indeno[1,2-<i>c</i>]azepines and azabicyclo[4.2.0]octa-1(8),5-dines is described
Gold-Catalyzed Cycloisomerization of 1,7-Diyne Benzoates to Indeno[1,2-<i>c</i>]azepines and Azabicyclo[4.2.0]octa-1(8),5-dines
No full textA synthetic method that relies on Au(I)-catalyzed cycloisomerization
reactions of 1,7-diyne benzoates to prepare indeno[1,2-<i>c</i>]azepines and azabicyclo[4.2.0]octa-1(8),5-dines is described
Gold-Catalyzed Cycloisomerization of 1,7-Diyne Benzoates to Indeno[1,2-<i>c</i>]azepines and Azabicyclo[4.2.0]octa-1(8),5-dines
No full textA synthetic method that relies on Au(I)-catalyzed cycloisomerization
reactions of 1,7-diyne benzoates to prepare indeno[1,2-<i>c</i>]azepines and azabicyclo[4.2.0]octa-1(8),5-dines is described
Gold-Catalyzed Cycloisomerization of 1,7-Diyne Benzoates to Indeno[1,2-<i>c</i>]azepines and Azabicyclo[4.2.0]octa-1(8),5-dines
No full textA synthetic method that relies on Au(I)-catalyzed cycloisomerization
reactions of 1,7-diyne benzoates to prepare indeno[1,2-<i>c</i>]azepines and azabicyclo[4.2.0]octa-1(8),5-dines is described
Gold-Catalyzed Domino Aminocyclization/1,3-Sulfonyl Migration of N‑Substituted <i>N</i>‑Sulfonyl-aminobut-3-yn-2-ols to 1‑Substituted 3‑Sulfonyl‑1<i>H</i>‑pyrroles
No full textA method
to prepare 1-substituted 3-sulfonyl-1<i>H</i>-pyrroles efficiently
that relies on the gold(I)-catalyzed cycloisomerization
of N-substituted<i> N</i>-sulfonyl-aminobut-3-yn-2-ols is
described. The method was shown to be applicable to a broad range
of 1,7-enyne alcohols containing electron-withdrawing, electron-donating,
and sterically demanding substrate combinations. The mechanism is
suggested to involve activation of the propargylic alcohol by the
Au(I) catalyst, which causes the intramolecular nucleophilic addition
of the sulfonamide unit to the alkyne moiety. The resulting nitrogen-containing
heterocyclic intermediate undergoes dehydration and deaurative 1,3-sulfonyl
migration, a process that remains rare in gold catalysis, to give
the aromatic nitrogen-containing product
Regarding a Persisting Puzzle in Olefin Metathesis with Ru Complexes: Why are Transformations of Alkenes with a Small Substituent <i>Z</i>‑Selective?
No full textAn enduring question in olefin metathesis
is that reactions carried
out with widely accessible Ru dichloro complexes, which typically
favor <i>E</i> alkenes, generate <i>Z</i> isomers
preferentially when substrates bearing a smaller substituent are used; <i>Z</i> enol ethers, alkenyl sulfides, 1,3-enynes, alkenyl halides,
or alkenyl cyanides can be prepared reliably with reasonable efficiency
and selectivity. Transformations thus proceed via the more hindered <i>syn</i>-substituted metallacyclobutanes, which is mystifying
because catalyst features implemented in the more recently developed
and broadly applicable <i>Z</i>-selective catalysts are
absent in the Ru dichloro systems. Herein, we describe experimental
and computational investigations that offer a plausible rationale
for these puzzling selectivity trends. The following will be demonstrated.
(1) Kinetic <i>Z</i> selectivity depends on the relative
barrier for olefin association/dissociation versus metallacyclobutane
formation/cleavage. There can be appreciable stereochemical control
when metallacyclobutane formation/breakage is turnover-limiting. (2)
Stereoelectronicnot purely stericeffects are central:
achieving the p-orbital overlap needed for alkene formation while
minimizing steric repulsion between the incipient olefin substituent
and a catalyst’s anionic ligand during the cycloreversion step
is crucial. We show that similar stereoelectronic factors are probably
operative in the more recently introduced <i>Z</i>-selective
(and enantioselective) olefin metathesis transformations promoted
by stereogenic-at-Ru complexes containing a bidentate aryloxide ligand
