Deoxygenation of Hydroquinones as a General Route to Norbornane-Fused Aromatic Systems: An Entry into Substituted and Functionalized Dimethano- and Methanoanthracenes

A high-yielding route to substituted and functionalized dimethanoanthracenes by the Pd-catalyzed deoxyenation of the corresponding hydroquinone precursors is described. Attempts were made to deoxygenate the 9,10-dimesylate, ditosylate, and ditriflate derivatives of <i>anti</i>-dimethanoanthracene <b>1a</b>, and it was found that under the studied conditions only the ditriflate <b>8a</b> gave the corresponding deoxygenated aromatic scaffold. Optimization of the reaction conditions identified the Pd­(OAc)₂/dppf tandem as a suitable catalytic system for this transformation. The presented strategy was further extended to a novel and efficient synthetic route to methanoanthracenes employing a one-pot Pd-catalyzed deoxygenation/hydrogenation sequence

Deoxygenation of Hydroquinones as a General Route to Norbornane-Fused Aromatic Systems: An Entry into Substituted and Functionalized Dimethano- and Methanoanthracenes

A high-yielding route to substituted and functionalized dimethanoanthracenes by the Pd-catalyzed deoxyenation of the corresponding hydroquinone precursors is described. Attempts were made to deoxygenate the 9,10-dimesylate, ditosylate, and ditriflate derivatives of <i>anti</i>-dimethanoanthracene <b>1a</b>, and it was found that under the studied conditions only the ditriflate <b>8a</b> gave the corresponding deoxygenated aromatic scaffold. Optimization of the reaction conditions identified the Pd­(OAc)₂/dppf tandem as a suitable catalytic system for this transformation. The presented strategy was further extended to a novel and efficient synthetic route to methanoanthracenes employing a one-pot Pd-catalyzed deoxygenation/hydrogenation sequence

<i>In Situ</i> Generation of the Coates Catalyst: A Practical and Versatile Catalytic System for the Carbonylation of <i>meso</i>-Epoxides

A highly active catalytic system for the carbonylation of meso- and terminal epoxides to β-lactones is described. The active catalyst, analogous to Coates’ catalyst, is generated in situ from commercially available (TPP)CrCl and Co2(CO)8. This practical system circumvents the preparation of air sensitive cobaltate salts, operates at low catalyst loadings, and allows the carbonylation of functionalized, sterically demanding and heterocyclic meso-epoxides

Unified Strategy for Iodine(III)-Mediated Halogenation and Azidation of 1,3-Dicarbonyl Compounds

A mild and rapid (diacetoxy­iodo)­benzene-mediated formal electrophilic α-azidation of 1,3-dicarbonyl compounds using commercially available Bu₄NN₃ as the azide source is reported. The reaction conditions employed are based on optimization studies conducted on the analogous halogenations with Et₄NX (X = Cl, Br, I)

Intermolecular Interactions in (Arene)chromium Carbonyl Compounds: Prediction of Chiral Crystal Packing from Racemate Structure

Six X-ray crystal structures are reported, all containing substituted triphenylmethanol derivative 4 either alone or as its mono or bis(chromium tricarbonyl) complexes. All four chromium complexes studied crystallize with two independent molecules in the crystallographic asymmetric unit. It is demonstrated that from the X-ray crystal structure of the acentric racemic (±)-(1pR,1‘ ‘R)(1pS,1‘ ‘S)-[Cr(CO)3(η6-t-BuC6H3(CMeOMe)CPh2OH)], (±)-3, it is possible to deduce the 4-fold helical structure of the chiral (−)-(1pR,1‘ ‘R) isomer, (−)-3. The bimetallic derivatives demonstrate the ability to control intermolecular interactions by the positioning of relative stereochemistry

Desulfurative Chlorination of Alkyl Phenyl Sulfides

The chlorination of readily available secondary and tertiary alkyl phenyl sulfides using (dichloroiodo)­benzene (PhICl₂) is reported. This mild and rapid nucleophilic chlorination is extended to sulfa-Michael derived sulfides, affording elimination-sensitive β-chloro carbonyl and nitro compounds in good yields. The chlorination of enantioenriched benzylic sulfides to the corresponding inverted chlorides proceeds with high stereospecificity, thus providing a formal entry into enantioenriched chloro-Michael adducts. A mechanism implying the formation of a dichloro-λ⁴-sulfurane intermediate is proposed

Desulfurative Chlorination of Alkyl Phenyl Sulfides

The chlorination of readily available secondary and tertiary alkyl phenyl sulfides using (dichloroiodo)­benzene (PhICl₂) is reported. This mild and rapid nucleophilic chlorination is extended to sulfa-Michael derived sulfides, affording elimination-sensitive β-chloro carbonyl and nitro compounds in good yields. The chlorination of enantioenriched benzylic sulfides to the corresponding inverted chlorides proceeds with high stereospecificity, thus providing a formal entry into enantioenriched chloro-Michael adducts. A mechanism implying the formation of a dichloro-λ⁴-sulfurane intermediate is proposed