Gold-Catalyzed Cycloisomerization-Halogenation Sequence of 1,3-Enyne Esters with NXS: Efficient Synthesis of 5-Bromo/Iodo Cyclopentenones

Gold(I)-Catalyzed Rautenstrauch/Hetero-Diels-Alder/Retro-aza-Michael Cascade Reaction for the Synthesis of α-Hydrazineyl-2-cyclopentenones

A one-pot synthesis of ring-fused, α-hydrazineyl-2-cyclopentenone derivatives is achieved by a gold(I)-catalyzed Rautenstrauch/hetero Diels-Alder/ring opening tandem reaction of suitable propargyl esters. By mixing the latter with a dialkylazodicarboxylate in the presence of a gold(I) catalyst, the 1,2-acyloxy migration/cyclization process (Rautenstrauch reaction) leads to cyclopentadienyl ester intermediates which are trapped by the heterodienophile present in situ. This provides strained intermediates which spontaneously undergo highly regioselective ring opening by a retro aza-Michael reaction promoted by the gold(I) catalyst, eventually yielding the target compounds. Six- and seven-membered ring-fused cyclopentenones bearing a pendant α-hydrazineyl moiety can be obtained in moderate to excellent yield (50-98%) by this approach, with a minimal erosion of the initial optical purity when using enantioenriched substrates.

Gold-Catalyzed Double Spirocyclization of 3-Ene-1,7-diyne Esters to Dispiroheterocycles

A synthetic method to prepare dispiroheterocycles containing two all-carbon quaternary centers efficiently that relies on the gold(I)-catalyzed double spirocyclization of 3-ene-1,7-diyne esters is described. The suggested mechanism delineates a rare example of a dispirocyclization featuring two 1,n-acyloxy shifts comprising a 1,3-acyloxy migration and an interrupted 1,5-acyl migration that was achieved with the assistance of residual water in the reaction media.

Recent progress in the homogeneous gold-catalysed cycloisomerisation reactions

This review focuses on recent advancements in the efficacy of gold catalysts for the cycloisomerisation of ynamides, diynes, and 1,n-enynes to build complex molecules, with critical insight into their mechanism and reaction scope.

Gold self-relay catalysis for accessing functionalized cyclopentenones bearing an all-carbon quaternary stereocenter

A new gold(i) self-relay catalysis consisting of a 3,3-rearrangement, Nazarov cyclization and Michael addition cascade of 1,3-enyne acetates with aurones and their derived azadienes is reported, producing functionalized cyclopentenones.