Jesús A. Varela

Cycloisomerization of aromatic homo- and bis-homopropargylic alcohols via catalytic Ru vinylidenes: formation of benzofurans and isochromenes.

Ru-catalyzed cycloisomerizations of aromatic homo- and bis-homopropargylic alcohols effectively afford benzofurans and isochromenes. These processes proved to be chemo- and regioselective (5-, and 6-endo cyclizations) derived from key Ru vinylidene intermediates. The presence of an amine/ammonium base-acid pair is crucial for the catalytic cycle.

Rh(III)-catalyzed tandem C-H allylation and oxidative cyclization of anilides: a new entry to indoles.

Rh(III)-catalyzed tandem C-H allylation and oxidative cyclization of anilides with allyl carbonates in the presence of a slight excess of AgSbF6 salt and Cu(OAc)2 as oxidant affords easy, economical access to important bioactive 2-methylindoles. The new reaction supports a wide range of functional groups on the anilide substrate. A possible mechanism is proposed as a basis for its rational further development.

Osmium-Catalyzed 7-endo Heterocyclization of Aromatic Alkynols into Benzoxepines†

We thank the MICINN (Spain) (CTQ2008-06557, CTQ2008-00810, Consolider Ingenio 2010 (CSD2007-00006)), Xunta de Galicia (2007/XA084 and INCITE08PXIB209024PR) and Diputacion General de Aragon (E35). A.V-F. thanks USC and XUGA for a predoctoral grant. C.G-Y. thanks MICINN for a Ramon y Cajal research contract.

Brønsted Acid-Promoted Intramolecular Carbocyclization of Alkynals Leading to Cyclic Enones

TFA-promoted exo carbocyclizations of nonterminal 7-alkynals gave good to excellent yields of seven-membered cycloalkenones, a medium-sized functionalized ring present in natural products with relevant pharmacological properties. Nonterminal 5- and 6-alkynals also gave very good yields of the corresponding exo cyclopentenones and cyclohexenones. On the other hand, terminal 5-alkynals gave endo carbocyclizations to cyclohexenones. These carbocyclizations can be considered as tandem alkyne hydration/aldol condensation processes.

Cyclization by Catalytic Ruthenium Carbene Insertion into C sp 3H Bonds

Novel reactions that can selectively functionalize carbon hydrogen bonds are very important because they offer new strategic approaches in synthesis. A remarkable method for such C H functionalization involves the insertion of metal carbenes into C H bonds. The regioselectivity of these C H insertions is governed by electronic, steric, and conformational factors. Typically, in nonconstrained systems, metalcatalyzed intramolecular C H insertion reactions predominantly afford five-membered rings (1,5-insertions). 4] The formation of smaller and larger rings is achieved only when geometrical constraints or activated C H bonds are involved. Usually, Rhand Cu-catalyzed C H insertions have shown amazing versatility in both intramolecular and intermolecular reactions, but it is still a challenging goal to discover other metals and tethers that facilitate the construction of rings by Csp3 H functionalization. Recently, special attention has been paid to Ptand Au-catalyzed intramolecular coupling between terminal unactivated alkynes and Csp3 H bonds in alkynyl ethers and amines to produce complex spiro or fused bicyclic systems by a tandem 1,5hydride shift/cyclization sequence. The above methods require temperatures as high as 100–120 8C to achieve good results and under Pt catalysis only 5-exo methylene bicyclic structures are formed. We report herein a mild procedure based on a novel tandem Ru-catalyzed carbene addition to terminal alkynes/insertion into Csp3 H bonds in alkynyl acetals, ethers, and amines to form complex spiro and fused bicyclic structures by 1,5and 1,6-hydride shift/cyclization sequences (Scheme 1). The cyclization of dioxolane 1 a was the first reaction examined under a variety of catalytic conditions (Table 1). After some preliminary experiments, the well-known conditions, established by Dixneuf and co-workers, for the preparation of Ru carbenes starting from alkynes were employed. Thus, a 1,5-hydride shift/cyclization sequence gave the functionalized spiro[5,5] compound 2a in a moderate yield of 40 % and the linear hydroxyester 3a as the major

An application of importance-performance analysis (IPA) to the management of sport centres

The importance-performance analysis (IPA) constitutes an approach to the measurement of customer/user satisfaction which allows for a simple and functional identification of both the strong and the weak aspects, or improvement areas, of a given service. Taking both the importance assigned by users to all relevant aspects of a given service and the perceived performance of the establishment in providing the service, a graph with four quadrants is obtained. This graph allows for (a) a very intuitive visual assessment of the management of the establishment and (b) the corresponding advice for a better distribution of organizational resources. Nevertheless, this tool has been subjected to controversy since its origins, due mainly to (a) the position of the axis determining the quadrants and (b) the conceptualization and measurement of both importance and performance of the elements of the service. In the present paper, the practical solution for some of these issues is posed, and the potential of IPA as a management tool for sport centres is illustrated.

Vinyl dihydropyrans and dihydrooxazines: cyclizations of catalytic ruthenium carbenes derived from alkynals and alkynones.

A novel synthesis of 2-vinyldihydropyrans and dihydro-1,4-oxazines (morpholine derivatives) from alkynals and alkynones has been developed. The cyclizations require a mild generation of catalytic ruthenium carbenes from terminal alkynes and (trimethylsilyl)diazomethane followed by trapping with carbonyl nucleophiles. Mechanistic aspects of the new cyclizations are discussed.

Nucleophilic Addition of Amines to Ruthenium Carbenes: ortho‐(Alkynyloxy)benzylamine Cyclizations towards 1,3‐Benzoxazines

A new ruthenium-catalyzed cyclization of ortho-(alkynyloxy)benzylamines to dihydro-1,3-benzoxazines is reported. The cyclization is thought to take place via the vinyl ruthenium carbene intermediates which are easily formed from [Cp*RuCl(cod)] and N2 CHSiMe3 . The mild reaction conditions and the efficiency of the procedure allow the easy preparation of a broad range of new 2-vinyl-2-substituted 1,3-benzoxazine derivatives. Rearrangement of an internal C(sp) in the starting material into a tetrasubstituted C(sp(3) ) atom in the final 1,3-benzoxazine is highly remarkable.

N-Doped Cationic PAHs by Rh(III)-Catalyzed Double C-H Activation and Annulation of 2-Arylbenzimidazoles with Alkynes

A novel class of N-doped cationic PAHs (polycyclic aromatic hydrocarbons) bearing the benzo[c,d]fluoranthene scaffold has been synthesized by the Rh(III)-catalyzed double-oxidative annulation of 2-arylbenzimidazoles with alkynes. The overall process involves a double C-N bond formation through a double C-H/N-H functionalization.The solid-state structures and electronic properties of the new N-doped PAHs were analyzed. These cationic azapolycycles were readily reduced in the presence of LiAlH4 or by the addition of PhLi to give interesting phenyl and diphenylmethanediamine derivatives.

Tandem Brønsted Acid Promoted and Nazarov Carbocyclizations of Enyne Acetals to Hydroazulenones

NOTICE: This is the peer reviewed version of the following article:Escalante, L., Gonzalez-Rodriguez, C., Varela, J. A., Saa, C. (2012). Tandem Bronsted Acid Promoted and Nazarov Carbocyclizations of Enyneacetals to Hydroazulenones. Angew. Chem. Int. Ed., 51, 49, 12316-12320. [doi: 10.1002/anie.201205823]. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for self-archiving.