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An S-shaped double helicene-like molecule (>99 % ee), possessing stable helical chirality, has been synthesized by the rhodium(I)/difluorphos complex-catalyzed highly diastereo- and enantioselective intramolecular double [2+2+2] cycloaddition of a 2-naphthol- and benzene-linked hexayne. The collision between two terminal naphthalene rings destabilizes the helical chirality of the S-shaped double helicene-like molecule, but the introduction of two additional fused benzene rings significantly increases the configurational stability. Thus, no epimerization and racemization were observed even at 100 °C. The enantiopure S-shaped double helicene-like molecule forms a trimer through the multiple C-H⋅⋅⋅π and C-H⋅⋅⋅O interactions in the solid-state. The trimers stack to form columnar packing structures, in which neighboring stacks have opposite dipole directions. The accumulation of helical structures in the same direction in the S-shaped double helicene-like molecule enhanced the chiroptical properties.

It has been established that a newly developed cyclopentadienyl rhodium(III) [CpA RhIII ] complex, bearing an acidic secondary amide moiety on the Cp ring, is able to catalyze the ortho-bromination of O-phenyl carbamates with N-bromosuccinimide (NBS) at room temperature. The presence of the acidic secondary amide moiety on the CpA ligand accelerates the bromination by the hydrogen bond between the acidic NH group of the CpA ligand and the carbonyl group of NBS.

The oxidative coupling of benzamides with methyl 2-trifluoromethylacrylate proceeds smoothly under rhodium(III) catalysis to produce trifluoromethyl-substituted isoindolinone derivatives. The catal...

It has been established that a cyclopentadienyl (Cp) RhIII complex with two aryl groups and a pendant amide moiety catalyzes the formal Lossen rearrangement/alkenylation cascade of N-pivaloyl heterole carboxamides with internal alkynes, leading to alkenylheteroles. Interestingly, the use of sterically demanding internal alkynes afforded not the alkenylation but the [3+2] annulation products ([5,5]-fused heteroles). In these reactions, the pendant amide moiety of the CpRhIII complex may accelerate the formal Lossen rearrangement. The use of five-membered heteroles may deter reductive elimination to form strained [5,5]-fused heteroles; instead, protonation proceeds to give the alkenylation products. Bulky alkyne substituents accelerate the reductive elimination to allow the formation of the [5,5]-fused heteroles.

It has been established that an electron-deficient CpRhIII complex, bearing two ester moieties on the Cp ring, [CpERhIII], catalyzes the aerobic oxidative cross coupling of substituted acrylamides ...

The smallest spherical carbon nanocage so far, [2.2.2]carbon nanocage, has been synthesized by the cationic rhodium(I)/H8 -binap complex-catalyzed regioselective intermolecular cyclotrimerization of a cis-1-ethynyl-4-arylcyclohexadiene derivative followed by the triple Suzuki-Miyaura cross-couplings with 1,3,5-triborylbenzene and reductive aromatization. This cage molecule is highly strained, and its ring strain is between those of [6] and [5]cycloparaphenylenes. A significant red-shift of an emission maximum was observed, compared with that of known [4.4.4]carbon nanocage. The sequential cyclotrimerizations of a cis-1,4-diethynylcyclohexadiene derivative with the same rhodium(I) catalyst followed by reductive aromatization failed to afford [1.1.1]carbon nanocage; instead, a β-graph-shaped cage molecule was generated.

It has been established that the dienylation of unfunctionalized arenes with 1,6-diynes, possessing aryl groups at the diyne termini, proceeds to give the corresponding dienylated arenes in the presence of a catalytic amount of an electron-deficient cyclopentadienyl rhodium(III) complex, [CpERhCl2]2, and a stoichiometric amount of silver carbonate. Experimental and theoretical mechanistic studies revealed that a CpERh(I) complex generated in situ might catalyze the present dienylation­ reaction.

It has been established that a newly developed moderately electron-deficient cyclopentadienyl (Cp)-Rh(III) complex, bearing ester and pendant amide moieties on the Cp ring [CpARh(III)], is able to catalyze the aerobic oxidative olefination of benzamides, bearing nonspecial carbamoyl groups, with styrenes including disubstituted ones at relatively low temp. (60-80 ﾂｰC). The presence of both the ester and pendant acidic N-phenylcarbamoyl moieties on the CpA ligand play important roles in facilitation of the catalysis without sacrificing thermal stability of the complex. [on SciFinder(R)]

It has been established that a chiral S-shaped [11]helicene-like mol. can be synthesized with high ee value along with a meso form by the rhodium(I)/(R)-difluorphos complex-mediated enantioselective intramol. double [2+2+2] cycloaddn. of a 2-naphthol-linked hexayne, even though this chiral helicene has the collision between the terminal benzene rings. Epimerization behavior of the chiral and meso [11]helicene-like mols. have also been disclosed. [on SciFinder(R)]

It has been established that a cationic rhodium(I)/(R)-tol-BINAP or (R)-BINAP complex catalyzes the enantioselective [2 + 2 + 1] cycloaddn. of 1,6-enynes, possessing monosubstituted alkene units, with cyclopropylideneacetamides at room temp. through the elimination of ethylene to give bicyclic (cyclopent-2-en-1-ylidene)acetamides with high enantioselectivity. [on SciFinder(R)]

It has been established that both racemic and homochiral forms of a diaryl-substituted dibenzo[7]helicene exhibit reversible mechanochromic luminescence. The racemic and homochiral crystals of this...

Pneumatic displacement of submacular hemorrhages (SMHs) with intravitreal injection of sulfur hexafluoride (SF6) gas with or without tissue plasminogen activator (tPA) and prone posturing is an effective minimally invasive treatment. We observed some cases in which simultaneous flattening of hemorrhagic pigment epithelial detachments (PEDs) occurred after prone posturing. This study evaluated the impact of pneumatic displacement using tPA to treat PEDs and visual outcomes in eyes with SMHs secondary to neovascular age-related macular degeneration (AMD). This retrospective analysis reviewed the medical records of 32 patients (33 eyes) who underwent pneumatic displacement for AMD-associated SMHs. The SMHs were related to polypoidal choroidal vasculopathy (PCV) in 24 eyes and typical AMD in nine eyes and treated with intravitreal injection of SF6 gas with tPA. We assessed the postoperative best-corrected visual acuities (BCVAs), prevalence and flattening rates of the PEDs, and the number of additional treatments. The mean follow-up period was 35.4 ± 19.8 months. The BCVAs improved significantly in eyes with PCV compared with eyes with typical AMD. Thirty-one (93.9%) of 33 eyes had an accompanying PED. The PEDs flattened in 14 (58.3%) of 24 eyes with PCV but in only one (14.3%) of seven eyes with typical AMD (p = 0.04). A mean of one additional treatment was administered during the first year in 15 eyes with flattened PEDs, which was significantly (p

The asymmetric synthesis of configurationally stable oxygen-linked Gelander-type p-terphenyls has been achieved via the rhodium-catalyzed diastereoselective intramolecular double [2+2+2] cycloaddition of chiral propargylic alcohol-derived hexaynes. Centrochirality of the chiral hexaynes induced the axial chirality to give the Gelander-type p-terphenyls as single stereoisomers. Photophysical and chiroptical properties of the thus synthesized Gelander-type p-terphenyls were examined, which revealed that the di-n-butyl- and diphenyl-substituted one shows efficient ultraviolet emission and a relatively large absorption dissymmetry ratio.

A new synthetic route to highly fluorescent benzofuranylmethylidenebenzoxasiloles through cationic rhodium(I)/binap complex-catalyzed cascade cycloisomerization of bis(2-ethynylphenol)silanes has been developed involving 1,2-silicon and 1,3-carbon (alkyne) migrations followed by oxycyclization. The present synthesis requires only three steps, starting from commercially available dichlorodiisopropylsilane, which is markedly shorter than our previous synthesis (eight steps starting from commercially available chlorodiisopropylsilane). Theoretical calculations elucidated the mechanism of the above cascade cycloisomerization. This reaction is initiated by the formation of a rhodium vinylidene not through direct 1,2-silicon migration but rather through an unprecedented stepwise 1,5-silicon migration followed by C-Si bond-forming cyclization from a dearomatized allenylrhodium complex. Subsequent 1,3-carbon (alkyne) migration leading to a η3 -allenyl/propargyl-rhodium complex followed by oxycyclization through π-bond (alkyne) activation with the cationic rhodium(I) complex affords the benzofuranylmethylidenebenzoxasilole product. The structure-fluorescence property relationships of the thus obtained benzofuranylmethylidenebenzoxasiloles were investigated, which revealed that good fluorescence quantum yields were generated in the solution state (φF =69-87 %) by introduction of electron-donating alkyl and phenyl groups on two phenoxy groups. In the powder state, 4-methyl- and 4-methoxy-phenoxy derivatives exhibited efficient blue fluorescence (φF =52 % and 46 %, respectively). Especially, the 4-methylphenoxy derivative was thermally stable, and exhibited strong narrow-band fluorescence in the film state (blue, φF =95 %) and redshifted strong narrow-band fluorescence (green, φF =90 %) in the crystalline state as a result of the formation of an offset π-stacked dimer; the latter was confirmed by X-ray crystallographic analysis and by theoretical calculations.

It has been established that a cyclopentadienyl RhIII complex with two phenyl groups and a pendant amide moiety catalyzes the formal Lossen rearrangement/[3+2] annulation cascade of N-pivaloyl benzamides and acrylamides with alkynes leading to substituted indoles and pyrroles. Mechanistic studies revealed that this cascade reaction proceeds via not the Lossen rearrangement to form anilides or enamides but C-H bond cleavage, alkyne insertion, and the formal Lossen rearrangement.

It has been established that reductive complexation of functionalized benzofulvenes, which are readily prepared from commercially available indene and 2-methylindene, with RhCl3 in ethanol affords the corresponding indenyl-rhodium(III) dichlorides bearing substituents at the 1- (H or CO2 Et), 2- (H or Me), and 3- [CH2 Ph or CH2 (2-MeOC6 H4 )] positions. The indenyl-rhodium(III) complexes bearing one ethoxycarbonyl group showed higher thermal stability and regioselectivity than our previously reported CpE RhIII complex toward the oxidative [3+2] annulation of acetanilides with internal alkynes.

The enantioselective synthesis of a phospha[9]helicene with a bibenzopicene skeleton has been achieved via the rhodium-mediated intermolecular [2+2+2] cycloaddition of a binaphthyl-linked tetrayne with a phosphorus-linked diyne. The photophysical and chiroptical properties of the thus obtained phospha[9]helicene were compared with our previously synthesized benzopicene-based carbo[9]helicene and triphenylene-based carbo- and phospha[7]helicenes. Significantly red shifted absorption and emission maxima were observed in the benzopicene-based phospha[9]helicene as a result of extended π-conjugation, but its fluorescence quantum yield and circularly polarized luminescence activity (glum) were lower than those of the other three helicenes.

It has been established that an electron-deficient (η5 -cyclopentadienyl)rhodium(III) [CpE RhIII ] complex is capable of catalyzing the decarboxylative and oxidative [2+2+2] annulation of benzoic acids with alkynes to produce substituted naphthalenes at room temperature. The appropriate choice of the additive and the solvent is crucial for this transformation. This catalyst system allowed use of oxygen as a terminal oxidant and broadened the substrate scope including both aromatic and aliphatic alkynes. In this catalysis, the electron deficient nature of the CpE RhIII catalyst would cause the strong rhodium-π interaction, which accelerates the decarboxylation as well as the C-H bond cleavage.

The synthesis of alternating donor-acceptor [12] and [16]cycloparaphenylenes (CPPs) has been achieved by the rhodium-catalyzed intermolecular cross-cyclotrimerization followed by imidation and/or aromatization. These alternating donor-acceptor CPPs showed positive solvatofluorochromic properties and smaller HOMO-LUMO gaps compared with nonfunctionalized CPPs, which was confirmed by the theoretical study.

The synthesis, characterization, and catalytic performance of iridium(III) catalysts that bear an amide-pendant cyclopentadienyl ligand ([CpA IrI2 ]2 ) is reported. These [CpA IrI2 ]2 catalysts were obtained from the complexation of a CpA ligand precursor with [Ir(cod)OAc]2 followed by oxidation. Double aromatic homologation reactions of benzamides with alkynes by fourfold C-H activation proceeded in good to high yield with these [CpA IrI2 ]2 catalysts, demonstrating their superior catalytic performance in this challenging transformation.

The enantioselective synthesis of distorted π-extended chiral triptycenes, consisting of three distinct aromatic rings, has been achieved with high ee value of 87 % by the cationic rhodium(I)/segphos complex-catalyzed enantioselective [2+2+2] cycloaddition of 2,2'-di(prop-1-yn-1-yl)-5,5'-bis(trifluoromethyl)-1,1'-biphenyl with 6-methoxy-1,2-dihydronaphthalene followed by the diastereoselective Diels-Alder reaction and aromatization. Demethoxy derivatives were also synthesized by the C-O bond cleavage. In this synthesis, the use of the electron-deficient diyne and the electron-rich alkene is crucial to suppress the undesired strain-relieving carbocation rearrangement and stabilize the distorted triptycene structure.

It has been established that a cyclopentadienyl (Cp) Rh

It has been established that an electron-deficient cyclopentadienyl rhodium(III) (CpE RhIII ) complex catalyzes the oxidative and decarboxylative [2+1+2+1] cycloaddition of benzoic acids with diynes through C≡C triple bond cleavage, leading to fused naphthalenes. This cyclotrimerization is initiated by directed ortho C-H bond cleavage of a benzoic acid, and the subsequent regioselective alkyne insertion and decarboxylation produce a five-membered rhodacycle. The electron-deficient nature of the CpE RhIII complex promotes reductive elimination giving a cyclobutadiene-rhodium(I) complex rather than the second intermolecular alkyne insertion. The oxidative addition of the thus generated cyclobutadiene to rhodium(I) (formal C≡C triple bond cleavage) followed by the second intramolecular alkyne insertion and reductive elimination give the corresponding [2+1+2+1] cycloaddition product. The synthetic utility of the present [2+1+2+1] cycloaddition was demonstrated in the facile synthesis of a donor-acceptor [5]helicene and a hemi-hexabenzocoronene by a combination with the chemoselective Scholl reaction.

It has been established that a RhI+/segphos complex catalyzes the [2+2+1] cycloaddition of 1,6-diynes with cyclopropylideneacetamides to give substituted fulvenes in good yields. The reductive complexation of the product fulvenes with RhCl3 in EtOH furnished the corresponding dinuclear cyclopentadienyl RhIII complexes bearing a pendant amide moiety. These RhIII complexes were highly active catalysts for oxidative annulation and cyclization through C(sp2)−H and C(sp3)−H functionalization.

The convenient synthesis of substituted benzopicenes and azabenzopicenes has been achieved by the cationic rhodium(I)/H8–BINAP or BINAP complex-catalyzed [2+2+2] cycloaddition under mild conditions. This method was applied to the synthesis of benzopicene-based long ladder and helical molecules. The X-ray crystal structure analysis revealed that the benzopicene-based helical molecule is highly distorted and the average distance of overlapped rings is markedly shorter than that in the triphenylene-based helical molecule. Photophysical and chiroptical properties of these benzopicene and azabenzopicene derivatives have also been examined. With respect to photophysical properties, substituted benzopicenes and azabenzopicenes showed red shifts of absorption and emission maxima compared with the corresponding triphenylenes and azatriphenylenes. With respect to chiroptical properties, the CPL spectra of the benzopicene-based helical molecule showed two opposite peaks, and thus the value of the CPL was smaller tha...

It has been established that cationic rhodium(I)/axially chiral biaryl bis(phosphine) complexes catalyze the asymmetric [2+2+2] cycloaddition of 1,6-enynes with electron-rich functionalized alkenes, enamides, and vinyl carboxylates, to produce the corresponding protected cyclohexenylamines and cyclohexenols. Interestingly, regioselectivity depends on structures of substrates. The present cycloaddition was successfully applied to the enantioselective total synthesis of (-)-porosadienone by using the amide moiety as a leaving group.

The cationic gold(I)/(R)-xyl-binap complex was shown to catalyze the atroposelective intramolecular hydroarylation of alkynones to produce enantioenriched axially chiral all-benzenoid biaryls, 4-aryl-2-naphthol derivatives, with up to 67 % ee. The reaction of a racemic alkynone in the presence of the same gold(I) catalyst also afforded the corresponding axially chiral all-benzenoid biaryl in excellent yield with 70 % ee.

The effects of bent linkers in diynes on the efficiency and selectivity of intermolecular macrocyclization by the rhodium-catalyzed sequential cross-cyclotrimerization of L-shaped diynes and di-tert-butyl acetylenedicarboxylate was investigated. A bulky triethylsilyl-protected cyclohexa-1,4-dienediol-linked diyne reacted with di-tert-butyl acetylenedicarboxylate to give the corresponding 16-membered macrocycle as well as the 12-membered macrocycle. Aromatization of the thus-obtained 12-membered macrocycle through desilylation followed by reductive aromatization with SnCl2 and HCl afforded a [12]cycloparaphenylenehexacarboxylate. The use of a conformationally flexible methoxymethyl-protected cyclohexanediol-linked diyne increased the yield of the corresponding 16-membered macrocycle, although oxidative aromatization leading to the corresponding cycloparaphenylenes was unsuccessful.

An electron-deficient Cp(E) rhodium(III) complex bearing a cyclopentadienyl ligand with two ethyl ester substituents catalyzes the tandem [2+2+2] annulation-lactamization of acetanilides with two alkynoates via cleavage of adjacent two C-H bonds to give densely substituted benzo[cd]indolones. The reactions of meta-methoxy-substituted acetanilides with two alkynoates also provided benzo[cd]indolones via cleavage of adjacent C-H/C-O bonds. Furthermore, 3,5-dimethoxyacetanilides reacted with two alkynoates to give dearomatized spiro compounds.

It has been established that a cationic rhodium(I)/axially chiral biaryl bisphosphine complex catalyzes the asymmetric [2 + 2 + 2] cycloaddition of α,ω-diynes with electron-rich and unstrained unsymmetrical 1,2-disubstituted alkenes to give chiral multicyclic compounds with good yields and ee values. Interestingly, enantioselectivity highly depends on the structures of α,ω-diynes used presumably due to the presence of two distinct reaction pathways.

It has been established that a cationic rhodium(I)/binap complex catalyzes the cross-cyclotrimerization of two molecules of a monosubstituted allene with one molecule of a functionalized alkyne to give 3,6-dialkylidenecyclohex-1-enes. In contrast, the reactions involving di- or trisubstituted allenes and/or unfunctionalized alkynes afforded cross-dimerization products, substituted dendralenes, through β-hydrogen elimination from the corresponding rhodacycles.

The enantioselective synthesis of an aza[10]helicene, possessing two pyridone units, has been achieved by the gold-catalyzed intramolecular quadruple hydroarylation of a tetrayne. This aza[10]helicene was successfully converted into a fully aromatic aza[10]helicene, possessing two pyridine units. Structure-photophysical and chiroptical properties relationship in a series of azahelicene isomers has also been disclosed.

It has been established that a strongly electrophilic η5-cyclopentadienylrhodium complex, [CpERhCl2]2, is capable of reacting with aliphatic alkenes in the presence of a silver salt and cesium acetate at room temperature to give the corresponding π-allyl complexes in high yields. The use of an alkenyltosylamide as the alkene also afforded the corresponding π-allyl complex. Treatment of the thus obtained π-allyl complex with a silver(I) salt and copper(II) acetate afforded the allylic amination product, which proves the intermediacy of this π-allyl complex in the rhodium(III)-catalyzed intramolecular oxidative allylic amination.