5 research outputs found
Phosphaannulation by Palladium-Catalyzed Carbonylation of C–H Bonds of Phosphonic and Phosphinic Acids
An
efficient phosphaannulation by Pd-catalyzed carbonylation of
C–H bonds of phosphonic and phosphinic acids for the synthesis
of oxaphosphorinanone oxides is reported. These compounds are novel
phosphorus heterocyclic scaffolds, thus opening a new avenue to sequential
C–C/C–O bond formation in one pot
Ruthenium-Catalyzed C–H Activation/Cyclization for the Synthesis of Phosphaisocoumarins
An
efficient and cost-effective ruthenium-catalyzed oxidative cyclization
of phosphonic acid monoesters or phosphinic acids with alkynes has
been developed for the synthesis of a wide range of phosphaisocoumarins
in good to excellent yields under aerobic conditions. A multitude
of arylphosphonic acid monoesters and arylphosphinic acids having
electron-donating and -withdrawing groups were oxidatively cyclized.
Various diarylacetylenes, dialkylacetylenes, and alkylarylacetylenes
effectively underwent the ruthenium-catalyzed oxidative cyclization.
A substrate possessing benzoic acid as well as a phenylphosphonic
monoester moiety was smoothly cyclized with hex-3-yne to afford a
compound having both isocoumarin and phosphaisocoumarin moieties.
Alkenylphosphonic monoester afforded phosphorus 2-pyrone through oxidative
cyclization with alkyne. Competition experiments between diaryl- and
dialkylalkynes and between diarylacetylenes having <i>p</i>-methoxy and <i>p</i>-chloro groups gave results which
showed that the present oxidative cyclizations were not affected by
the electronic effects of alkynes. Mechanistic studies revealed C–H
bond metalation to be the rate-limiting step
Synthesis of Multisubstituted Allenes, Furans, and Pyrroles via Tandem Palladium-Catalyzed Substitution and Cycloisomerization
A palladium-catalyzed
propargyl substitution reaction of propargyl
acetates with indium organothiolates is developed for the synthesis
of multisubstituted allenyl sulfides. This procedure can be applied
to the synthesis of multisubstituted furans and pyrroles via tandem
palladium-catalyzed propargyl substitution and cycloisomerization
reaction in one pot
Alkenylation of Phosphacoumarins via Aerobic Oxidative Heck Reactions and Their Synthetic Application to Fluorescent BenzoÂphosphaÂcoumarins
Alkenylation of phosphacoumarins
is developed from the reaction
of phosphacoumarins with a variety of activated as well as nonactivated
alkenes via aerobic oxidative Heck reactions. In addition, 3-alkenylÂphosphaÂcoumarins
undergo an inverse electron demand Diels–Alder reaction (IEDDA)
with enamines <i>in situ</i> generated from ketone and pyrrolidine
followed by 1,2-elimination and a dehydrogenation, producing fluorescent
benzoÂphosphaÂcoumarins
Synthesis of 2‑Alkoxyaryl-2-aryl Enamines via Tandem Copper-Catalyzed Cycloaddition and Rhodium-Catalyzed Alkoxyarylation from Alkynes, <i>N</i>‑Sulfonyl Azides, and Aryl Ethers
A synthetic route
to a wide range of 2-alkoxyaryl-2-aryl enamines
is developed from Rh-catalyzed alkoxyarylation of <i>N</i>-sulfonyl-4-aryl-1,2,3-triazoles with aryl ethers via the elimination
of nitrogen molecule. In addition, 2-alkoxyaryl-2-aryl enamines are
prepared via tandem Cu-catalyzed cycloaddition and Rh-catalyzed alkoxyarylation
starting from alkynes, <i>N</i>-sulfonyl azides, and aryl
ethers in one-pot