Efficient synthesis of fluorinated triphenylenes with enhanced arene-perfluoroarene interactions in columnar mesophases.

The high potential of non-covalent arene-fluoroarene intermolecular interactions in the design of liquid crystals lies in their ability to strongly promote self-assembly, improve the order and stability of the supramolecular mesophases, and enable tuneability of the optical and electronic properties, which can potentially be exploited for advanced applications in display technologies, photonic devices, sensors, and organic electronics. We recently successfully reported the straightforward synthesis of several mesogens containing four lateral aliphatic chains and derived from the classical triphenylene core self-assembling in columnar mesophases based on this paradigm. These mesogenic compounds were simply obtained in good yields by the nucleophilic substitution (SFAr) of various types of commercially available fluoroarenes with the electrophilic organolithium derivatives 2,2'-dilithio-4,4',5,5'-tetraalkoxy-1,1'-biphenyl (2Li- ).

Palladium-Catalyzed Annulation Reaction of Bay-Iodobiphenyls with Maleimides to Access 9,10-Phenanthrenedicarboximides.

A palladium-catalyzed annulation reaction of bay-iodobiphenyls with maleimides was developed. This approach allows for the efficient synthesis of a variety of 9,10-phenanthrenedicarboximides, particularly polyalkoxy-substituted 9,10-phenanthrenedicarboximides with potential liquid-crystalline properties. Research findings indicate that the resulting product, -hexyl-2,3,6,7-tetrakis(hexyloxy)-9,10-phenanthrenedicarboximide, exhibits promising, good liquid-crystalline properties.

Nickel-Catalyzed Reductive Dicarbofunctionalization of 1,3-Dienes with Aziridines and (Het)Aryl Electrophiles.

A three-component reductive 1,4-dicarbofunctionalization of 1,3-dienes with aziridines and (het)aryl electrophiles was realized. The combination of Ni catalysis with Mn powder as a final reductant enables the direct formation of a Csp-Csp and a Csp-Csp bond at one time. This protocol afforded a convenient approach to the synthesis of β-arylethylamines bearing various functionals and heterocyclic groups.

Nickel-Catalyzed Enantioselective Carbonyl Addition of Aryl Chlorides and Bromides to Aldehydes.

The Ni-catalyzed enantioselective addition reaction of aryl halides to aldehydes was studied with cyanobis(oxazoline) as chiral ligands and Mn as reductant. Aryl and heteroaryl bromides reacted with phenyl aldehyde at room temperature to produce dibenzyl alcohols in 16-99 % yields with 53-92 % ees. Moreover, the coupling of phenyl chloride with a variety of aryl, heteroaryl and alkyl aldehydes was demonstrated in the presence of cyanobis(oxazoline)/Ni(II) at 60 °C in generally high yields with moderate enantioselectivities.

Palladium-Catalyzed Annulative π-Extension of Bay-Iodinated Triphenylenes to Access Polycyclic Aromatic Compounds.

A palladium-catalyzed annulative π-extension reaction of bay-iodinated triphenylenes with aryl iodides/-chloroaromatic carboxylic acids was developed. This approach enabled the synthesis of diverse polycyclic aromatic compounds, including dibenzo[,]tetracenes, azadibenzo[,]tetracenes, and tribenzo[,,]coronenes. Initial studies indicate that the resulting product, 2,3,8,9,14,15-hexakis(decyloxy)tribenzo[,,]coronene, exhibits good liquid-crystalline properties.

Enantioselective Ir-Catalyzed Allyl Alkylation/Semipinacol Rearrangement.

The semipinacol rearrangement is a powerful and versatile method for constructing all-carbon quaternary stereocenters. The development of catalytic asymmetric semipinacol rearrangements using multifunctionalizable electrophiles remains highly sought-after in organic synthesis. In this study, a catalytic enantioselective allylic cation-induced semipinacol rearrangement reaction was presented that enables the simultaneous construction of two skipped chiral carbon centers.

Diastereo- and Enantioselective Synthesis of Tetracyclic Cycloheptanols through (4+3) Annulation via C-C/C-H Activation Cascade.

Transition metal-catalyzed annulations of four-membered rings via C-C activation are powerful tools to construct complex fused and bridged ring systems. Despite significant progress in (4+1), (4+2) and (4+4) annulations, the (4+3) annulation remains unexplored. Herein, we develop an asymmetric Rh-catalyzed intramolecular (4+3) annulation of α-arylalkene-tethered benzocyclobutenols for the synthesis of dihydrofuran-annulated dibenzocycloheptanols with two discontinuous chiral carbon centers via a C-C and C-H activation cascade.

Transition-Metal-Catalyzed C-C Bond Formation from C-C Activation.

ConspectusC-C single bonds are ubiquitous in organic compounds. The activation and subsequent functionalization of C-C single bonds provide a unique opportunity to synthesize conventionally inaccessible molecules through the rearrangement of carbon skeletons, often with a favorable atom and step economy. However, the C-C bonds are thermodynamically and kinetically inert.

Nickel-Catalyzed Reductive Cross-Coupling of Aziridines and Allylic Chlorides.

A nickel-catalyzed reductive cross-coupling of aziridines and allylic chlorides was realized by using manganese metal as the reducing agent. This protocol afforded a convenient approach to obtain β-allyl-substituted arylethylamines bearing various functional groups. The utility of this reaction was also demonstrated by scale-up preparation and diverse transformations, including the synthesis of Baclofen and several bioactive molecular motifs.

Induction and Stabilization of Columnar Mesophases in Fluorinated Polycyclic Aromatic Hydrocarbons by Arene-Perfluoroarene Interactions.

The straightforward synthesis of several Fluorinated Polycyclic Aromatic Hydrocarbons by the efficient, transition-metal-free, arene fluorine nucleophilic substitution reaction is described, and the full investigation of their liquid crystalline and optical properties reported. The key precursors for this study, i. e.

Nickel-Catalyzed Reductive Three-Component Cross-Coupling of Butadiene with Aldehydes and Alkenyl Triflates/Bromides: Access to Skipped Dienes.

A regio- and stereoselective nickel-catalyzed reductive three-component cross-coupling of 1,3-butadiene with aldehydes and alkenyl triflates or bromides was realized. This protocol afforded a convenient approach to the synthesis of skipped diene compounds bearing various functionals and heterocyclic groups. The utility of this reaction was also demonstrated by scale-up preparation and diverse transformations.

Pyrene-Fused Poly-Aromatic Regioisomers: Synthesis, Columnar Mesomorphism, and Optical Properties.

π-Extended pyrene compounds possess remarkable luminescent and semiconducting properties and are being intensively investigated as electroluminescent materials for potential uses in organic light-emitting diodes, transistors, and solar cells. Here, the synthesis of two sets of pyrene-containing π-conjugated polyaromatic regioisomers, namely 2,3,10,11,14,15,20,21-octaalkyloxypentabenzo[,,,,]pentaphene () and 2,3,6,7,13,14,17,18-octaalkyloxydibenzo[,]phenanthro [9,10-]picene (), is reported. They were obtained using the Suzuki-Miyaura cross-coupling in tandem with Scholl oxidative cyclodehydrogenation reactions from the easily accessible precursors 1,8- and 1,6-dibromopyrene, respectively.

Palladium-catalyzed annulative π-extension of -halobiphenyls with -chloropyridinecarboxylic acids to access azatriphenylenes.

A palladium-catalyzed bay-region annulative π-extension reaction of -halobiphenyls with -chloropyridinecarboxylic acids was developed. The reaction was carried out with a 1 : 1 ratio of substrates. A variety of azatriphenylene derivatives could be synthesized by this approach.

Modular Synthesis of Enantioenriched α-Chiral Homoallylic Amidines Enabled by Relay Ir/Cu Catalysis.

The cascade of Ir-catalyzed enantioselective allylic amination and Cu-catalyzed alkyne-azide cycloaddition was designed for the asymmetric synthesis of homoallylic amidines. The nucleophilic addition of an in situ-generated enantioenriched tertiary allylamine to a ketenimine intermediate triggers a rapid and stereospecific zwitterionic aza-Claisen rearrangement in a 1,3-chiral transfer manner. The approach allows modular access to enantioenriched α-chiral homoallylic amidines in high yields with a high level of enantiomeric purity.

Nickel-Catalyzed Three-Component Cross-Electrophile Coupling of 1,3-Dienes with Aldehydes and Aryl Bromides.

We herein report a Ni-catalyzed three-component cross-electrophile coupling of 1,3-dienes with aldehydes and aryl bromides using manganese metal as the reducing agent. This efficient protocol accomplishes dicarbofunctionalization of 1,3-dienes to synthesize diverse structural 1,4-disubstituted homoallylic alcohols by forming two new C-C bonds in one time. Mechanistic study suggests that an allyl-nickel(I) species is involved in the catalytic cycle.

Regiocontrolled Annulation of Benzocyclobutenols with Alkynes.

A tandem reaction that involves an unprecedented Rh-catalyzed intramolecular annulation of benzocyclobutenols with alkynes and subsequent ZnCl-promoted dehydration was developed, offering an efficient approach to 2-furan-, pyran-, and oxepine-fused naphthalenes. Furthermore, the 2-furan motif may undergo a ring-opening reaction through Fe-catalyzed reductive C-O bond cleavage. As a consequence, the formal intermolecular annulation of 2-hydroxybenzocyclobutenols with alkynes was realized with complete regioselectivity through a two-step protocol.

Pd-Catalyzed Enantioselective (3+2)-Cycloaddition of Vinyl-Substituted Oxyallyl Carbonates with Isocyanates and Ketones.

The vinyl-substituted oxyallyl carbonates were exploited as a new C,O-dipole for enantioselective Pd-catalyzed (3+2) cycloaddition. The corresponding oxyallyl-Pd species was weakly nucleophilic to react with activated carbonyl compounds, affording multisubstituted and enantioenriched oxazolidinones and 1,3-dioxolanes with a high degree of chemo- and stereoselectivity. The synthetic transformations of oxazolidinone product were carried out to build enantioenriched α-chiral aminoketone and epoxy derivatives.

Concise synthesis and applications of enantiopure spirobiphenoxasilin-diol and its related chiral ligands.

The development of chiral architectures for chiral ligand and catalyst discovery is essential for asymmetric catalysis. Herein, we report the concise synthesis of a Si-centered spirocyclic skeleton, spirobiphenoxasilin-diol (SPOSiOL), and its derived chiral ligands. Using the chemical resolution method, the optical SPOSiOL could be obtained in high yield on a gram scale.

Bay-Region Annulative π-Extension of -Iodobiphenyls with Aliphatic Anhydrides Catalyzed by Pd(OAc).

Bay-region annulative π-extension of -iodobiphenyls with aliphatic anhydrides was developed. Many -iodobiphenyls and aliphatic anhydrides can react well under the optimized conditions. A lot of phenanthrol derivatives can be efficiently prepared by this approach.

Skeleton Reorganization of Substituted Benzocyclobutenols through Rh-Catalyzed C-C Bond Cleavage Manipulated by Hydrogen Transfer.

Although transition-metal-catalyzed C-C bond activation has been investigated extensively, C-C bond cleavage manipulated by hydrogen transfer has been unexplored. In this work, we disclose a skeleton reorganization of alkene-tethered benzocyclobutenols through Rh-catalyzed C-C bond cleavage coupled with intra- and intermolecular hydrogen transfer. The reaction pathway was well-tuned by the catalytic systems.

Site-Selective C-C Cleavage of Benzocyclobutenones Enabled by a Blocking Strategy Using Nickel Catalysis.

Controlling the chemo- and regioselectivity of transition-metal-catalyzed C-C activation remains a great challenge. The transformations of benzocyclobutenones (BCBs) usually involve the cleavage of C1-C2 bond. In this work, an unprecedented highly selective cleavage of C1-C8 bond with the insertion of alkynes is achieved by using blocking strategy via Ni catalysis, providing an efficient method for synthesis of 1,8-disubstituted naphthalenes.

Synthesis of Tribenzo[,,]azepines via Palladium-Catalyzed Annulation Reaction of 2-Iodobiphenyls with 2-Halogenoanilines.

A palladium-catalyzed annulation reaction of 2-iodobiphenyls with 2-halogenoanilines has been developed. A variety of 2-iodobiphenyls and 2-halogenoanilines can undergo this transformation. Diversified tribenzo[,,]azepine derivatives can be synthesized in moderate to excellent yields according to this method.

Remote Regioselective Radical C-H Functionalization of Unactivated C-H Bonds in Amides: The Synthesis of -Difluoroalkenes.

The site-selective functionalization of unactivated aliphatic amines is an attractive and challenging synthetic approach. We herein report a general strategy for the remote site-selective functionalization of unactivated C(sp)-H bonds in amides by photogenerated amidyl radicals to form -difluoroalkenes with trifluoromethyl-substituted alkenes. The site selectivity is controlled by a 1,5-hydrogen atom transfer (HAT) process of the amide.