Acid-Promoted Iso-Nazarov Cyclization of Conjugated trans-Dienones and Dienals for the Synthesis of 2-Cyclopentenones

The acid-promoted cyclization of all-trans linearly conjugated dienones and dienals constitutes a synthetic strategy for the construction of 2-cyclopentenones.

Cp*Co(III)-Catalyzed Ketone-Directed ortho-C-H Activation for the Synthesis of Indene Derivatives

A weakly coordinating, carbonyl-assisted C-H activation of aromatic systems with α,β-unsaturated ketone and subsequent aldol condensation has been developed using a Cp*Co(CO)I₂ catalyst. The developed method is the first example of indene synthesis by cobalt-catalyzed C-H activation. In addition, the reaction requires mild reaction conditions and easily accessible starting materials, and it shows excellent functional group compatibility.

Lewis Base-Catalyzed Enantioselective Conjugate Reduction of β,β-Disubstituted α,β-Unsaturated Ketones with Trichlorosilane: E/Z-Isomerization, Regioselectivity, and Synthetic Applications

The chiral bisphosphine dioxide-catalyzed asymmetric conjugate reduction of acyclic β,β-disubstituted α,β-unsaturated ketones with trichlorosilane affords saturated ketones having a stereogenic carbon center at the carbonyl β-position with high enantioselectivities. Because the E/Z-isomerizations of enone substrates occur concomitantly, reduction products with the same absolute configurations are obtained from either (E)- or (Z)-enones. Conjugate reduction is accelerated in the presence of an electron-rich aryl group at the β-position of the enone owing to its carbocation-stabilizing ability. Computational studies were also conducted in order to elucidate the origin of the observed enantioselectivity. The regio- and enantioselective reductions of dienones were realized and applied to the syntheses of ar-turmerone, turmeronol A, mutisianthol, and jungianol, which are optically active sesquiterpenes.

Construction of polycyclic bridged indene derivatives by a tandem 1,3-rearrangement/intramolecular Friedel-Crafts cyclization of propargyl acetates

An unprecedented Lewis acid-catalyzed cascade 1,3-rearrangement/Friedel-Crafts cyclization of propargyl acetates is developed for the construction of polycyclic bridged indene derivatives in moderate to good yields. This practical procedure features mild conditions, broad substrate scope, and easy operation.

Nazarov reaction: current trends and recent advances in the synthesis of natural compounds and their analogs

Recent applications of the Nazarov reaction to stereoselective synthesis of pharmacology-relevant cyclopentenone scaffolds are summarized.

One-pot C–C/C–O bond formation: synthesis of spirocyclic lactones

An efficient and practical method for the synthesis of novel spiro(tri or tetra)cyclic lactones via the formation of C–C and C–O bonds in one-pot is presented.

FeCl3 mediated synthesis of substituted indenones by a formal [2+2] cycloaddition/ring opening cascade of o-keto-cinnamates

A novel FeCl₃ mediated formal [2+2] cycloaddition/ring opening cascade of o-keto-cinnamates was developed for the synthesis of indenones. The reaction tolerates a broad range of functional groups, including bromide, chloride, amide, acid and ester groups.