Golden aryne? Gold aryne complexes are inferred as transition states in dual gold‐catalyzed cyclizations of cis‐enediynes (see scheme; DCE=1,2‐dichloroethane). They are better described as ortho‐aurophenyl cations, which react with weak nucleophiles and undergo facile intramolecular insertions into C(sp3)H bonds. Indanes, fused heteroarenes, and phenol derivatives are readily prepared using this method.

No abstract

Goldenes Arin? Gold‐Arin‐Komplexe werden als Übergangszustände in dualen Gold‐katalysierte Cyclisierungen von cis‐Endiinen angenommen (siehe Schema; DCE=1,2‐Dichlorethan); sie werden besser beschrieben als ortho‐Aurophenyl‐Kationen, die mit schwachen Nucleophile reagieren und leichte intramolekulare Insertionen in C(sp3)‐H‐Bindungen eingehen. Mit der Methode wurden Indane, kondensierte Heteroarene und Phenolderivate auf einfache Weise hergestellt.

No abstract

Ther eactiono fa ni nternal alkyne with 2,6-dichloropyridine N-oxide,anucleophilic oxidant, and electrophilic N-iodosuccinimide (NIS)s imultaneously enables the direct access to versatile a-iodoenones.E lectronically biased internala lkynes undergo the one-stept ransformation with excellent regioselectivities andw ith practical Z/E ratios.I n comparison to the relatedo xidative gold catalysis using pyridine N-oxides,t his reaction employs NIS as the stoichiometric ynophile instead of the soft acidic noble metal catalyst and affords products featuring an additional versatileC À Ib ond. Similar strategies for replacing ynophilic cationic gold(I) complexes in oxidative gold catalysis with likewise ynophilic stoichiometric electrophiles would enable the development of new synthetic methods.Keywords: alkynes;e nones; iodination;o xidation; pyridine N-oxides a-Iodoenones possess an electrophilic enone moiety susceptible to either 1,4-or 1,2-addition andaversatile C À Ib ondf or transitionm etal catalysis.A ss uch, they are valuables tructures in organic synthesis. Theirs yntheses have been achieved mostly via iodination of functional substrates such as enones, [1] a-silyl/stannyla,b-unsaturated ketones, [2] propargylic alcohols [3] and their ester counterparts, [4] and occasionally via oxidation of iodinated allylica lcohols.[5] Therei ss eldom an approacht hat accomplishesb otho xidation and iodination in ac ollaborative fashion in one step from substrates with lesser degreeso fo xidation/functionalization.[6] Herein, we report an implementation of this approachu sing minimally functionalized internal alkyne substrates. Fort he past several years our group [7] and others [8] have reported the applications of an oxidative gold catalysis strategy in the development of versatiles ynthetic methods. As shown in Approach Ao f Scheme 1A, the coordination of as oft Lewis acidic gold catalyst to aC Ct riple bond triggers the attack of an ucleophilic oxidanta ti ts p bond. Thei nitial adduct can undergo fragmentation of the inherently weak O À Zb ond to offer expedient access to versatile a-oxo gold carbenes;a lternatively,i tm ay proceed to functionalized productsw ithout the carbene intermediacy in the presenceo famore facile reactionp athway.D ue to the catalytic nature of this chemistry,t he in situ generated Au À Cb ond in this class of reactions Scheme1.Replacingg old catalysts with stoichiometric electrophiles in the oxidationo fa lkynes by nucleophilic oxidants.