Alkynyl iodonium triflates, cycloaddition

A study of the regioselectivity of the 1,3-dipolar cycloaddition of aliphatic nitrile oxides with cinnamic acid esters has been published. AMI MO studies on the gas-phase 1,3-dipolar cycloaddition of 1,2,4-triazepine and formonitrile oxide show that the mechanism leading to the most stable adduct is concerted. An ab initio study of the regiochemistry of 1,3-dipolar cycloadditions of diazomethane and formonitrile oxide with ethene, propene, and methyl vinyl ether has been presented. The 1,3-dipolar cycloaddition of mesitonitrile oxide with 4,7-phenanthroline yields both mono-and bis-adducts. Alkynyl(phenyl)iodonium triflates undergo 2 - - 3-cycloaddition with ethyl diazoacetate, Ai-f-butyl-a-phenyl nitrone and f-butyl nitrile oxide to produce substituted pyrroles, dihydroisoxazoles, and isoxazoles respectively." 2/3-Vinyl-franwoctahydro-l,3-benzoxazine (43) undergoes 1,3-dipolar cycloaddition with nitrile oxides with high diastereoselectivity (90% de) (Scheme IS)." " ... 

The AuCl-catalysed 4 + 2-cycloaddition of benzyne with o-alkynyl(oxo)benzenes produced anthracene derivatives having a ketone in the 9-position, in good to high yields under mild conditions.118 Hypervalent iodine compounds, [5-acyl-2-(trimethyl-silyl)]iodonium triflates, readily yielded acylbenzynes which could be trapped with furan.119 Both DMAD and benzyne reacted with borabenzene to yield substituted borabarrelenes and borabenzobarrelenes, respectively.120... 

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