ABSTRACT
A two-step Ir-catalyzed borylation/Pd-catalyzed dehalogenation sequence allows for the net synthesis of fluoroarenes where the boronic ester is ortho to fluorine. Key elements of this approach include the use of a halogen para to the fluorine to block meta Ir-catalyzed borylation and the chemoselective Pd-catalyzed dehalogenation by KF activated polymethylhydrosiloxane (PMHS).
Subject(s)
Boron Compounds/chemical synthesis , Hydrocarbons, Fluorinated/chemistry , Hydrocarbons, Fluorinated/chemical synthesis , Boron Compounds/chemistry , Catalysis , Iridium/chemistry , Molecular Structure , Palladium/chemistry , Siloxanes/chemistry , StereoisomerismABSTRACT
A rhodium(I)-xylyl-BINAP catalyzed asymmetric [2 + 2 + 2] cycloaddition of achiral conjugated aryl ynamides with various diynes is described here. This asymmetric cycloaddition provides a series of structurally interesting chiral N,O-biaryls with excellent enantioselectivity along with a modest diastereoselectivity with respect to both C-C and C-N axial chirality.
ABSTRACT
A Rh(I)-catalyzed asymmetric [2 + 2 + 2] cycloaddition of achiral ynamides is described here. This work demonstrates a unique concept of stereochemical control of both the C-C and C-N axial chirality and provides an approach to the synthesis of chiral N,O-biaryls as well as chiral anilides.
Subject(s)
Carbon/chemistry , Nitrogen/chemistry , Crystallography, X-Ray , Models, Molecular , Molecular Structure , StereoisomerismABSTRACT
A Rh(I)-catalyzed demethylation-cyclization sequence for a direct transformation of o-anisole-substituted ynamides to benzofurans is described here. The Ag salt functions synergistically with Rh(I) for the key demethylation step.
Subject(s)
Alkynes/chemistry , Amides/chemistry , Anisoles/chemistry , Benzofurans/chemical synthesis , Organometallic Compounds/chemistry , Rhodium/chemistry , Benzofurans/chemistry , Catalysis , Crystallography, X-Ray , Cyclization , Methylation , Models, Molecular , Molecular Structure , StereoisomerismABSTRACT
Rhodium(I)-catalyzed [2 + 2 + 2] cycloadditions of sterically encumbered aryl-substituted ynamides with various diynes are described here. These cycloadditions provide the synthesis of an array of new chiral amide-substituted biaryls that can be useful in future chiral ligand designs.
Subject(s)
Alkynes/chemistry , Amides/chemistry , Rhodium/chemistry , Catalysis , Cyclization , Molecular Structure , StereoisomerismABSTRACT
A general and efficient method for the coupling of a wide range of amides with alkynyl bromides is described here. This novel amidation reaction involves a catalytic protocol using copper(II) sulfate-pentahydrate and 1,10-phenanthroline to direct the sp-C-N bond formation, leading to a structurally diverse array of ynamides including macrocyclic ynamides via an intramolecular amidation. Given the surging interest in ynamide chemistry, this atom economical synthesis of ynamides should invoke further attention from the synthetic organic community.
