@article {42458, title = {Copper-catalyzed synthesis of 2-unsubstituted, n-substituted benzimidazoles}, journal = {Journal of Organic Chemistry}, volume = {74}, year = {2009}, month = {NOV}, pages = {9570{\textendash}9572}, abstract = {

An efficient copper-catalyzed intramolecular arylation of formamidines forming 2-unsubstituted benzimidazoles in excellent yields is reported. Sixteen examples bearing sterically demanding substituents on nitrogen like Mes, 2,6-diisopropylphenyl, or 2-tert-butylphenyl and tolerating various functional groups demonstrate the utility of this method.

}, doi = {10.1021/jo902160y}, author = {Hirano, Keiichi and Biju, Akkattu T. and Glorius, Frank} } @article {42457, title = {N-heterocyclic carbene-catalyzed hydroacylation of unactivated double bonds}, journal = {Journal of the American Chemical Society}, volume = {131}, year = {2009}, month = {SEP}, pages = {14190{\textendash}14191}, abstract = {

An intramolecular N-heterocyclic carbene (NHC)-catalyzed hydroacylation of unactivated double bonds is reported. Systematic variation of the catalyst structure revealed an N-mesitylthiazolylidene annulated with a seven-membered ring to be especially reactive. This NHC enables a unique C-C bond-forming reaction to afford substituted chroman-4-ones in moderate to excellent yields, even ones containing all-carbon quaternary centers.

}, doi = {10.1021/ja906361g}, author = {Hirano, Keiichi and Biju, Akkattu T. and Piel, Isabel and Glorius, Frank} } @article {42459, title = {Switching the electron-donor properties of n-heterocyclic carbenes by a facile deprotonation strategy}, journal = {Chemistry an Asian Journal}, volume = {9}, year = {2009}, month = {DEC}, pages = {1786{\textendash}1789}, abstract = {

Flip the switch! The facile and distinct variation of the electronic properties of an N-heterocyclic carbene (NHC) ligand is reported. In this process, a simple deprotonation/protonation strategy can render the NHC to be an electron-poor or an electron-rich NHC ligand: one ligand, two electronic natures.

}, keywords = {carbenes; electronic properties; enolates; heterocycles; ligand design}, doi = {10.1002/asia.200900410}, author = {Biju, Akkattu T. and Hirano, Keiichi and Frohlich, Roland and Glorius, Frank} } @article {42454, title = {Intermolecular N-heterocyclic carbene-catalyzed hydroacylation of arynes}, journal = {Angewandte Chemie-International Edition}, volume = {49}, year = {2010}, month = {DEC}, pages = {9761{\textendash}9764}, abstract = {

A formal introduction: The conceptually new N-heterocyclic carbene catalyzed formal insertion of arynes into the Cformyl[BOND]H bond of aldehydes demonstrates the compatibility of nucleophilic NHCs with electrophilic arynes. This NHC-catalyzed hydroacylation of arynes allows the conversion of aliphatic, α,β-unsaturated, and aromatic aldehydes into aryl ketones; 27 examples and a preliminary mechanistic investigation are provided.

}, doi = {10.1002/anie.201005490}, author = {Biju, Akkattu T. and Glorius, Frank} } @article {42453, title = {N-heterocyclic carbene-catalyzed cascade reaction involving the hydroacylation of unactivated alkynes}, journal = {Journal of the American Chemical Society}, volume = {132}, year = {2010}, month = {APR}, pages = {5970{\textendash}5971}, abstract = {

The N-heterocyclic carbene (NHC)-catalyzed hydroacylation of unactivated alkynes to provide α,β-unsaturated ketones is reported. In addition, a rare case of an efficient and selective dually NHC-catalyzed cascade reaction involving the hydroacylation of alkynes and a subsequent intermolecular Stetter reaction allows the formation of chromanones containing a 1,4-diketone moiety.

}, doi = {10.1021/ja102130s}, author = {Biju, Akkattu T. and Wurz, Nathalie E. and Glorius, Frank} } @article { ISI:000295817100054, title = {Efficient synthesis of benzofuranones: N-heterocyclic carbene (NHC)/base-catalyzed hydroacylation-stetter-rearrangement cascade}, journal = {Organic Letters}, volume = {13}, number = {20}, year = {2011}, month = {OCT}, pages = {5624-5627}, publisher = {AMER CHEMICAL SOC}, address = {1155 16TH ST, NW, WASHINGTON, DC 20036 USA}, abstract = {

A N-heterocyclic carbene/base-catalyzed cascade reaction leading to the formation of functionalized benzofuranones is reported. The reaction proceeds via an intramolecular hydroacylation of unactivated alkynes followed by an intermolecular Stetter reaction and a base-catalyzed chromanone to benzofuranone rearrangement.

}, issn = {1523-7060}, doi = {10.1021/ol2023483}, author = {Padmanaban, Mohan and Biju, Akkattu T. and Glorius, Frank} } @article {42452, title = {Extending nhc-catalysis: reaction of aldehydes with unconventional reaction partners}, journal = {Accounts of Chemical Research}, volume = {44}, year = {2011}, month = {JUL}, pages = {1182{\textendash}1195}, abstract = {

Transition metal catalysis is a powerful means of effecting organic reactions, but it has some inherent drawbacks, such as the cost of the catalyst and the toxicity of the metals. Organocatalysis represents an attractive alternative and, in some cases, offers transformations unparalleled in metal catalysis. Unique transformations are a particular hallmark of N-heterocyclic carbene (NHC) organocatalysis, a versatile method for which a number of modes of action are known. The NHC-catalyzed umpolung (that is, the inversion of polarity) of electrophilic aldehydes, through formation of the nucleophilic Breslow intermediate, is probably the most important mode of action. In this Account, we discuss the reaction of Breslow intermediates with unconventional reaction partners.

}, doi = {10.1021/ar2000716}, author = {Biju, Akkattu T. and Kuhl, Nadine and Glorius, Frank} } @article { ISI:000295259700041, title = {N-Heterocyclic carbene catalyzed umpolung of michael acceptors for intermolecular reactions}, journal = {Angewandte Chemie-International Edition}, volume = {50}, number = {36}, year = {2011}, month = {AUG}, pages = {8412-8415}, publisher = {WILEY-V C H VERLAG GMBH}, address = {BOSCHSTRASSE 12, D-69469 WEINHEIM, GERMANY}, abstract = {

eahciM! The N-heterocyclic carbene catalyzed umpolung of Michael acceptors proceeds through the formation of a deoxy-Breslow intermediate (see scheme; EWG=electron-withdrawing group). This nucleophilic species can react with other Michael acceptors in an intermolecular fashion, thereby resulting in the formation of homo- or heterodimeric olefins. This {\textquotedblleft}Michael umpolung{\textquotedblright} should become a valuable method for the formation of densely functionalized olefins.

}, keywords = {carbenes, Michael acceptors, nitrogen heterocycles, organocatalysis, umpolung}, issn = {1433-7851}, doi = {10.1002/anie.201103555}, author = {Biju, Akkattu T. and Padmanaban, Mohan and Wurz, Nathalie E. and Glorius, Frank} } @article {42450, title = {N-heterocyclic carbene-catalyzed cross-coupling of aromatic aldehydes with activated alkyl halides}, journal = {Organic Letters}, volume = {13}, year = {2011}, month = {NOV}, pages = {98{\textendash}101}, abstract = {

N-Heterocyclic carbene-catalyzed umpolung of aldehydes followed by their interception with diarylbromomethanes has been reported. This conceptually novel transition-metal-free cross-coupling of aldehydes with alkyl halides works well at low catalyst loadings and under mild reaction conditions leading to the formation of diaryl acetophenone derivatives in good yields. In addition, α-halo ketones and esters can also be used as aldehyde reaction partners.

}, doi = {10.1021/ol102626p}, author = {Padmanaban, Mohan and Biju, Akkattu T. and Glorius, Frank} } @article {42451, title = {Synthesis and application of a chiral diborate}, journal = {Journal of Organic Chemistry}, volume = {76}, year = {2011}, month = {MAR}, pages = {2324{\textendash}2327}, abstract = {

A chiral diborate with different counterions is reported whose structure was unambiguously confirmed by X-ray analysis. This chiral dianion was used in the resolution of trans-1,2-diamines and also as a chiral shift reagent for NMR analysis of triphenylphosphonium salts.

}, doi = {10.1021/jo102559s}, author = {Loewer, Yvonne and Weiss, Christine and Biju, Akkattu T. and Frohlich, Roland and Glorius, Frank} }