The synthesis of aromatic amines is of utmost importance in aw ide range of chemical contexts.W er eport ad irect amination of boronic acids with nitro compounds to yield (hetero)aryl amines.T he novel combination of ad ioxomolybdenum(VI) catalyst and triphenylphosphine as inexpensive reductant has revealed to be decisive to achieve this new CÀNc oupling. Our methodology has proven to be scalable,a ir and moisture tolerant, highly chemoselective and engages both aliphatic and aromatic nitro compounds.M oreover,t his general and step-economical synthesis of aromatic secondary amines showcases orthogonality to other aromatic amine syntheses as it tolerates aryl halides and carbonyl compounds.Scheme 1. Direct aminationw ith nitroarenes:state-of-the-art.

The cross-coupling reaction of alkenyl bromides with thiols catalyzed by palladium complexes derived from inexpensive dppf ligand is reported. These reactions occur under low catalyst loading and in high yields and display wide scope, including the coupling of bulky thiols and trisubstituted bromoolefins, and functional group tolerance. In addition, the thioetherification of less reactive chloroalkenes and, for the first time, alkenyl tosylates was accomplished using a catalyst generated from CyPF tBu alkylbisphosphine ligand.

Skipped diynones, efficiently prepared from biomass -derived ethyl lactate, undergo a tandem hydra-tionoxacyclization reaction under gold(I)-catalysis. Reaction conditions have been developed for a switchable process that allows selective access to 4-pyrones or 3(2H)-furanones from the same starting diynones. Further application of this methodology in the total synthesis of polyporapyranone B was demonstrated.

Dedicated to Professor Julio Delgado Martín on the occasion of his 70th birthdayAllenes [1] are useful reagents for the [2+2] cycloaddition reaction, [2] which is a powerful process for the synthesis of cyclobutanes. This carbocyclic motif is present in bioactive compounds [3] and has unique reactivity. [4] Gold catalysis triggers the functionalization of allenes [5] and assists several intramolecular allenene reactions [6] which allow the preparation of bicyclic frames that contain cyclobutane motifs. [7] The gold-catalyzed enantioselective intramolecular [2+2] reaction of allenenes has been recently accomplished. [7b, 8] Moreover, racemic versions of related intermolecular processes have been disclosed. [9] An enantioselective version is highly desirable as it would provide a yet unknown and straightforward entry into optically active cyclobutanes from readily available allenamides and alkenes, in a sole synthetic operation. We are pleased to report herein the first asymmetric gold-catalyzed intermolecular allenene[2+2] cycloaddition.At the start of this study, previous work on the goldcatalyzed cyclization of allenamides and alkenes supported a stepwise reaction (Scheme 1). [9] The activation of the allene Scheme 1. Gold-catalyzed [2+2] intermolecular allene-alkene cycloaddition.Scheme 2. Ligands for the intermolecular [2+2] gold(I)-catalyzed enantioselective cycloaddition of the allenamide 1 a and styrene 2 a. Tf = trifluoromethanesulfonyl, Ts = 4-toluenesulfonyl.

Gold(III)-catalyzed cycloisomerization of α-bis(indol-3-yl)methyl alkynols selectively affords 1-(indol-3-yl)carbazoles, in a transformation that takes place through a selective 1,2-alkyl vs 1,2-vinyl migration step in the vinyl-gold intermediate generated from the initial 5-endo-spirocyclization. The reaction proceeds well with either tertiary or secondary starting alkynols as well as with a wide variety of alkyne substituents. The key role of the other indol-3-yl substituent for the unexpected selectivity in the 1,2 rearrangement has also been supported by DFT calculations that reveal a low barrier, two-step mechanism in the alkyl migration path where the second indole significantly stabilizes a carbocationic intermediate.