Nitrone and nitroso species are versatile compounds to react with alkenes or butadienes to access five-ands ix-membered nitroxy (N À O) containing heterocycles,t oo ffer further access to acyclic 1,3-and 1,4-aminoa lcohols after facile cleavage of the N À Ob onds.T he N-andO -functionalizationso f alkynes with nitroneso rn itroso species have been explored less wellt han the corresponding alkene reactions.I nr ecent decades,g old catalysts have enabled the electrophilic activation of alkynes with weak nucleophiles.T hisr eview summarizes recent progress to implement N-and O-functionalizations of alkynes with common N À Oc ontainings pecies including nitrone,n itroso,n itro and other nitroxy derivatives.R eportedr eactions include the following three topics:( i) 1,2-difunctionalizations,( ii)c yclizations and (iii)c ycloaddition or annulation reactions. Ther eview is organized according to the typeso fn ucleophiles,f ollowed by reactions of the mentioned types.E nantioselective functionalizations of alkynes with these nitroxy nucleophiles are also included.

Scheme 3. Deuterium-labeling experiments.Scheme 4. The reaction using diazocarbonyl.Scheme 5. The nature of CÀH insertion.Scheme 6. A plausible reaction mechanism.

Kinetically unstable nitrones are generated from gold-catalyzed reactions of 1,6-enynes with N-hydroxyanilines, and subsequently trapped by tethered alkenes to furnish [2+2+1]-annulations. Our experimental data reveal that such nitrones arise from atypical N-attack chemoselectivity that is triggered by tethered alkenes to facilitate the key protodeauration reaction.

Going for gold! Gold-catalyzed reactions of 3,5- and 3,6-dienynes with 8-alkylquinoline oxides results in an oxidative cycloaddition with high stereospecificity (see scheme; EWG = electron-withdrawing group); this process involves a catalytic activation of a quinoline framework. The reaction mechanism involves the intermediacy of α-carbonyl pyridinium ylides (I) in a concerted [3+2]-cycloaddition with a tethered alkene.

Cu-catalyzed oxidative Povarov reactions between N,N-dialkylanilines and saturated oxa- or thiacycles with tert-butyl hydroperoxide (TBHP) are described; notably, the reactions use neither [4π] nor [2π]-motifs as the initial reagents. The use of cheap alkane-based substances as building units is of mechanistic and practical interest as two inert sp(3) C-H bonds are activated.

We report a gold-catalyzed [2+2+2]-cycloaddition of 1,7-enynes with carbonyl species; our experimental data suggest that the resulting oxacyclic cycloadducts arose from an interception of gold-containing cyclobutenium intermediates with carbonyl species.

We report a highly stereoselective Au-catalyzed synthesis of 9-oxabicyclo[3.3.1]nona-4,7-dienes from diverse 1-oxo-4-oxy-5-ynes. Formation of these highly strained anti-Bredt oxacycles implies the workability of an unprecedented 1,4-dipole of s-trans-methylene(vinyl)oxonium. This work reveals the feasibility of a formal [4 + 2] cycloaddition on an s-trans-heterodiene framework.

A technique of "Grindstone chemistry" is applied to the solvent-free halogenation of arenes with NaCl, NaBr or I 2 using (diacetoxyiodo)benzene as the oxidant. Improved yields and higher purities of the products are observed compared with those from established methods.