Synthesis of Polysubstituted Fused Pyrroles by Gold-Catalyzed Cycloisomerization/1,2-Sulfonyl Migration of Yndiamides
Yndiamides (bis-N-substituted alkynes) are valuable precursors to azacycles. Here we report a cycloisomerization/1,2-sulfonyl migration of alkynyl-yndiamides to form tetrahydropyrrolopyrroles, unprecedented heterocyclic scaffolds that are relevant to medicinal chemistry. This functional group tolerant transformation can be achieved using Au(I) catalysis that proceeds at ambient temperature, and a thermally promoted process. The utility of the products is demonstrated by a range of reactions to functionalize the fused pyrrole core.
Smith, Philip J.,Jiang, Yubo,Tong, Zixuan,Pickford, Helena D.,Christensen, Kirsten E.,Nugent, Jeremy,Anderson, Edward A.
supporting information
p. 6547 - 6552
(2021/08/30)
External Oxidant-Free Oxidative Tandem Cyclization: NaI-Catalyzed Thiolation for the Synthesis of 3-Thiosubstituted Pyrroles
A simple method for the synthesis of 3-thiosubstituted pyrroles from homopropargylic amines and thiosulfonates via a tandem sulfenylation/cyclization has been developed. The thiosulfonates are used both as substrates and oxidants in this transformation. This procedure exhibits good functional group tolerance and a series of 3-thiosubstituted pyrrole derivatives was obtained in moderate to good yields. (Figure presented.).
Acid-catalyzed chirality-transferring intramolecular Friedel-Crafts cyclization of α-hydroxy-α-alkenylsilanes
Acid-catalyzed intramolecular Friedel-Crafts cyclization of optically active α-hydroxy-α-alkenylsilanes possessing a benzene ring (>99% ee) with TMSOTf as a Lewis acid gave enantio-enriched tetrahydronaphthalenes (up to 98% ee). The silyl group attached to the chiral carbon played a crucial role in the chirality transfer.
Cu-Catalyzed Tandem Aerobic Oxidative Cyclization for the Synthesis of 3,3′-Bipyrroles from the Homopropargylic Amines
A Cu-catalyzed method for the synthesis of 3,3′-bipyrroles from homopropargylic amines through tandem aerobic oxidative cyclization involving the formation of C-C bond has been developed. The features of this reaction are a small number of Cu catalysis and simple starting substrates. Moreover, this procedure exhibits good functional group tolerance and a series of 3,3′-bipyrroles derivatives are obtained in moderate to good yields.
Rhodium(III)-catalyzed oxidative bicyclization of 4-arylbut-3-yn-1-amines with internal alkynes through C-H functionalization
A new Rh(III)-catalyzed oxidative bicyclization through C-H functionalization is presented. This reaction allows the selective assembly of diverse benzo[g]indoles from 4-arylbut-3-yn-1-amines and internal alkynes via a sequence of aromatic C(sp2)-H functionalization, cyclodimerization and nucleophilic cyclization.
Stabilisation of carbon-supported palladium nanoparticles through the formation of an alloy with gold: Application to the Sonogashira reaction
A conceptually novel strategy based on the use of a bimetallic Pd-Au/C catalyst and its application to the Sonogashira reaction under ligand- and additive-free conditions was studied. Pd(OAc)2 and charcoal were dispersed in MeOH (100 mL). Then, hydrogen gas was bubbled through the solution for 5 min to remove the oxygen. The resulting mixture was stirred for 12 h at 25°C under H2. The catalyst was filtered under Millipore membrane washed with MeOH and dried under vacuum. ICP analyses were performed on the filtrate to verify the final Pd metal loading on carbon to be 5%wt. Detailed HR-TEM analyses established that the aggregation phenomenon can be considerably slowed down thanks to the stabilising, but catalytically inactive, gold atoms. Although X-ray photoelectron spectroscopy (XPS) analysis identified Au0 and Pd0 as the major species present in the as-prepared material, some ionic palladium (19 at.%) was also detected
The combination of relay and cooperative catalysis with a gold/palladium/brnsted acid ternary system for the cascade hydroamination/ allylic alkylation reaction
The combination of relay and cooperative catalysis with a gold/palladium/Brnsted acid ternary system renders a cascade hydroamination/allylic alkylation reaction to provide an unprecedented entry to pyrrolidine derivatives in high yields. Copyright
Wu, Hua,He, Yu-Ping,Gong, Liu-Zhu
supporting information; experimental part
p. 975 - 980
(2012/05/20)
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