A general catalytic system for the coupling of aryl halides and sulfonates with thiols based on the use of the CyPF-t-Bu ligand (1) is reported. The reactions catalyzed by complexes of 1 occur in excellent yields with broad scope and exhibit extraordinary turnover numbers and high tolerance of functional groups. Turnover numbers usually exceed those of previous catalysts by 2 or 3 orders of magnitude. In addition, the reactions of aryl tosylates with alkane thiols to form aryl sulfides are reported for the first time. Finally, the synthesis of a diarylsulfide from two bromoarenes was accomplished using a hydrogen sulfide surrogate.

The cross-coupling reaction of aryl chlorides with aliphatic and aromatic thiols catalyzed by palladium complexes of the strongly binding bisphosphine CyPF-tBu ligand (1) is reported. Most of the reactions catalyzed by complexes of ligand 1 occur with turnover numbers that exceed those of previous catalysts by two orders of magnitude. The reactions occur with excellent yields, broad scope and high tolerance of functional groups. Coupling of aryl halides with thiols in the presence of low loadings of catalysts derived from other Josiphos type ligands, as well as ligands of other structural types, are also described.

Abstract.Pinacol is described as a new chemoselective and environmentally benign reducing agent for sulfoxides and nitroaromatics assisted by readily available dichlorodioxomolybdenum(VI) complexes as catalysts. A wide range of substrates including those bearing challenging functional groups have been efficiently and selectively reduced being acetone and water the only byproducts of these reactions.

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.

Molecules containing the 1H-indene scaffold show a wide range of biological activities, [1] and possess great interest as functional materials, [2] as well as precursors of metallocene complexes as for catalytic polymerization processes.[3] So, several methodologies have been developed for their synthesis. [4] Despite the unquestionable interest of optically active indenes bearing the C-1 as stereogenic center, as far as we know, only two closely related strategies for the enantioselective synthesis of these compounds from achiral substrates have been published. [5][6][7][8] Both of them are based on the use of boronic acid derivatives as starting materials and dicationic Pd(II) complexes as catalyst. Thus, enantioenriched 1-arylindenes have been obtained in a cascade 1,4-addition-aldol condensation process, [5] whereas 1H-indenes bearing a CH 2 COR group at the C-1 position are formed from ortho-boronate substituted cinnamic ketones and internal alkynes. [6,7] The scarcity of general methods for the synthesis of optically active indenes (in particular from achiral substrates) aimed us to initiate a project in this field. Our premise was the use of easily available starting materials and, therefore, we fixed our attention on the catalytic cyclization of ortho-(alkynyl)styrenes. In this context, it should be taken into consideration that the skeletal rearrangement of ortho-(alkynyl)styrenes catalyzed by several metallic complexes has been described to afford naphthalene derivatives through a 6-endo cyclization process (Scheme 1, eq. 1).[9-13] However, a careful examination of all these publications showed that reactions with o-(alkynyl)styrenes where the terminal carbon of the alkene was disubstituted were not reported. So, we envisaged that o-(alkynyl)styrenes possessing a highly substituted alkene moiety and an internal acetylene could favour the 5-endo reaction pathway, due to a better stabilization of the exocyclic carbocationic intermediate, to form the desired indene skeleton with a stereogenic center at C-1 (Scheme 1, eq. 2).[14] Herein we report our success on this unprecedented metal-catalyzed 5-endo-dig cyclization of o-(alkynyl)styrenes and the application of this reaction in the synthesis of enantiomerically-enriched indenes. For the initial assays we selected 2´,2´-dimethyl o-(phenylethynyl)styrene 1a as a model substrate (Scheme 2). Due to their excellent ability to activate alkynes, [15] several complexes derived from coinage metals and platinum were tested as catalysts for the desired transformation. However, no reaction was observed with metal complexes such us AgSbF 6 , PtCl 2 , [PtCl 2 (cod)], CuI, AuCl 3 , AuCl or [AuCl(Ph 3 P)]. Encouragingly, the reaction proceeded to completion within 30 min to yield the indenyl derivative 2a in a high isolated yield (88%), when it was performed in dichloromethane at room temperature in the presence of the cationic gold(I) complex generated in situ from 5 mol% of [AuCl(Ph 3 P)] and 5 mol% of AgSbF 6 .[16] Moreover, when this reaction was conducted in the p...

The cross-coupling reaction of aryl bromides and iodides with aliphatic and aromatic thiols catalyzed by palladium complexes of the bisphosphine ligand CyPF-tBu (1) is reported. Reactions occur in excellent yields, broad scope, high tolerance of functional groups and with turnover numbers that exceed those of previous catalysts by two or three orders of magnitude. These couplings of bromoand iodoarenes are more efficient than the corresponding reactions of chloroarenes and could be conducted with less catalyst loading and/or milder reaction conditions. Consequently, limitations regarding scope and functional group tolerance previously reported in the coupling of aryl chlorides are now overcome.

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For the first time, nitriles are used as 2pi electron component in a gold-catalyzed intermolecular hetero-dehydro-Diels-Alder cycloaddition with captodative enynes leading to the regioselective formation of pyridines.