Dearomative Michael addition involving enals and 2-nitrobenzofurans realized under NHC-catalysis

In the manuscript the first enantioselective dearomative Michael addition between α,β-unsaturated aldehydes and 2-nitrobenzofurans realized under N-heterocyclic carbene activation has been described. The reaction proceeds via addition of homoenolate to Michael acceptors leading to the formation of biologically important heterocycles with high yields and stereoselectivities. Their functionalization potential has been confirmed in selected, diastereoselective transformations.

Transition Metal Catalyst Free Cross-Coupling Reaction of Tertiary Propargylic Alcohols with Hetero-Areneboronic Acids

We report a perfluorophenylboronic acid catalyzed cross coupling reaction of tertiary propargylic alcohols and hetero-areneboronic acids for valuable benzo[b]thiophene and cyclopenta[a]indene derivates. This coupling reaction proceeds efficiently with a wide array of substrates scope in up to 89% yield and excellent regioselectivity. A significant advantage of our protocol is the transition metal catalyst free and mild conditions needed. This strategy provides direct and facile access to medicinally important benzo[b]thiophene and cyclopenta[a]indene scaffold containing a quaternary carbon center.

Synthesis of Isoquinoline-1,3(2H,4H)-diones by Visible-light-mediated the Cyclization of Acryloylbenzamides with Alkyl Boronic Acids, Arylsulfonylhydrazides and Oxime Esters

An efficient visible-light-mediated tandem reaction of acryloylbenzamides with alkyl boronic acids, arylsulfonylhydrazides and oxime esters is developed. The reaction proceeds the radical addition and cyclization to give various isoquinoline-1,3(2H,4H)-diones in satisfactory yields under mild conditions, which provides a good opportunity to discover new meaningful bioactive compounds.

Catalytic Asymmetric β-Oxygen Elimination

A catalytic enantioselective β-O-elimination reaction is reported in the form of a zirconium-catalyzed asymmetric opening of meso-ketene acetals. Furthermore, a regiodivergent β-O-elimination is demonstrated. The reaction proceeds under mild conditions, at low catalyst loadings, and produces chiral monoprotected 1,2-diol building blocks in good yield and enantiomeric excess. The combination with a Mitsunobu reaction then gives access to all 1,2-diol stereoisomers and trans-1,2-aminoalcohols in high enantiomeric purity. A stereochemical analysis supported by DFT calculations reveals that a high selectivity in the hydrozirconation step is also important for achieving high enantioselectivity, although it does not constitute the asymmetric step. This insight is crucial for the future development of related asymmetric β-elimination reactions.

Dearomative [4 + 3] cycloaddition of furans with vinyl-N-triftosylhydrazones by silver catalysis: stereoselective access to oxa-bridged seven-membered bicycles

The first example of dearomative [4 + 3] cycloaddition between furans and vinyl-N-sulfonylhydrazones as vinylcarbene precursors is reported. The merger of silver catalysis and easily decomposable vinyl-N-triftosylhydrazones enabled the efficient synthesis of a variety of skeletally and functionally diverse oxa-bridged seven-membered bicyclic compounds with complete and predictable stereoselectivity. The combination of experimental studies and DFT calculations disclosed that the silver-catalyzed reaction proceeds via a concerted [4 + 3] cycloaddition mechanism, rather than the generally accepted cyclopropanation / Cope rearrangement pathway by rhodium catalysis.

Additive-free selective methylation of secondary amines with formic acid over a Pd/In2O3 catalyst

Formic acid is used as the sole carbon and hydrogen source in the methylation of aromatic and aliphatic amines to methylamines. The reaction proceeds via a formylation/transfer hydrogenation pathway over...

Hypophosphite Addition to Alkenes Under Solvent-Free and Non-Acidic Aqueous Conditions

Hypophosphite adds to alkenes in high yields under solvent-free conditions at elevated temperature, including ,-unsaturated carboxylates. The reaction proceeds by a radical mediated pathway. Hypophosphite addition is also effective under...

Cobalt-Catalyzed Highly Diastereoselective [3+2] Carboannulation Reaction: Facile Access to Substituted Indane Derivatives

An efficient oxidative [3+2] annulation reaction of aryl hydrazones and heterobicyclic alkenes has been realized with inexpensive and earth-abundant cobalt-salts under aerobic conditions. The reaction proceeds via directing-group assisted C-H...

Palladium-catalyzed stereoselective trifluoromethylated allylic alkylation of 3-substituted oxindoles

An efficient catalytic methodology for trifluoromethylated allylic alkylation of 3-substituted oxindoles using α-(trifluoromethyl)alkenyl acetates as trifluoromethyl-containing allylic alkylation partner is described. The reaction proceeds smoothly with the incorporation of Pd(OAc)2...

Silver(I) catalyzed Dehydrogenative Cross-Coupling of 2-Aroylbenzofurans with Phosphites

Silver(I) catalyzed dehydrogenative cross-coupling reaction of 2-aroylbenzofurans with phosphites to afford 2-aroyl-3-phosphonylbenzofurans is reported. The dehydrogenative cross-coupling reaction proceeds through conversion of silver(I) cation into silver(II) cation by peroxodisulfate followed...