Alkynes, cycloaddition with diaryl

SCS-MP2 and the new perturbative B2-PLYP density functional methods provide accurate reaction barriers and outperform MP2 and B3-LYP methods when applied to the 1,3-dipolar cycloaddition reactions of ethylene and acetylene.39 Phosphepine has been shown to catalyse the asymmetric 3 + 2-cycloaddition of allenes with a variety of enones (e.g. chalcones) to produce highly functionalized cyclopentenes with good enantiomeric excess.40 The AuPPh3SbF6 complex catalysed the intramolecular 3 + 2- cycloaddition of unactivated arenyne- (or enyne)-yne functionalities under ambient conditions.41 A review of the use of Rh(I)-catalysed 3 + 2-cycloadditions of diaryl-and arylalkyl-cyclopropenones and aryl-, heteroaryl-, and dialkyl-substituted alkynes to synthesise cyclopentadienones for use in the synthesis of natural products, polymers, dendrimers, and antigen-presenting scaffolds has been presented.42... 

A promising one-step route via rhodium-catalyzed double [2-I-2-1-2] cycloaddition was described for the synthesis of tetra-ort/70-substituted axially chiral diaryls from the diyne and tetrayne substrates produced from available alkynes [66]. Enantioselective syntheses of both C2 symmetric and asymmetric tetra-ort/ o-substituted axially chiral diaryls 2.72 and 2.75 through the rhodium-catalyzed [2-I-2-I-2] double cycloaddition of either 2.70 or 2.73 to the diyne 2.71 or tetrayne 2.74, respectively, gave products with ee 99% (Scheme 2.26) [66]. 

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