A Paternò-Büchi Reaction of Aromatics with Quinones under Visible Light Irradiation.

Reported herein is a Paternò-Büchi reaction of aromatic double bonds with quinones under visible light irradiation. The reactions of aromatics with quinones exposed to blue LED irradiation yielded oxetanes at -78 °C, which was attributed to both the activation of double bonds in aromatics and the stabilization of oxetanes by thiadiazole, oxadiazole, or selenadiazole groups. The addition of Cu(OTf)2 to the reaction system at room temperature resulted in the formation of diaryl ethers via the copper-catalyzed ring opening of oxetanes in situ. Notably, the substrate scope was extended to general aromatics.

A Molecular Cage Accessed by Threefold Click Reaction of a C3v-Symmetric Triazido-Functionalized Tribenzotriquinacene.

The hitherto unknown hexakis(halomethyl)-functionalized tribenzotriquinacenes (TBTQs) 9 and 10 were synthesized from the key 4b,8b,12b-tribromo-TBTQ derivative 6 by an improved route in 67% overall yield. Extension of the bowl-shaped framework of 9 or 10 by threefold condensation with propargylamine or 2-azidoethylamine afforded the corresponding TBTQ-trialkyne 11 and TBTQ-triazide 12, respectively. While attempts to construct bis-TBTQ cages, including homodimerization of 11 and heterocoupling of 11 with 12, were unsuccessful, triazide 12 was found to undergo threefold [3 + 2]-cycloaddition with 3-ethynylaniline and phloroglucinol tripropargyl ether under click chemistry conditions. The latter reaction enabled facile capping of the TBTQ bowl to give the novel cage compound 5 in 22% yield.

Synthesis of Enantiopure Hydrocarbon Cages Based on an Optically Resolved C3-Symmetric Triaminotribenzotriquinacene.

The synthesis of the enantiomerically pure, D3-symmetric covalent hydrocarbon cages (+)-(M,M)-4 and (-)-(P,P)-4 bearing two C3-symmetrically functionalized tribenzobenzotriquinacene (TBTQ) vertices is reported. The enantiomerically pure TBTQ building blocks (+)-(M)-5 and (-)-(P)-5 were prepared via the diastereomeric TBTQ triamides obtained by use of both Boc-d- and Boc-l-phenylglycine as chiral auxiliaries.

Enantioselective Formal Synthesis of (+)-Cycloclavine and Total Synthesis of (+)-5-epi-Cycloclavine.

Starting from the commercially available 4-bromoindole, a concise and efficient enantioselective formal synthesis of (+)-cycloclavine (1) in 13 steps with 2.0% overall yield and a total synthesis of (+)-5-epi-cycloclavine (2) in 14 steps with 3.3% overall yield were achieved. Key features of the syntheses include the addition of a Grignard reagent to the C═N/Heck reaction sequence to construct the fused 6-5-6 ring systems, cyclopropanation, an ester aminolysis reaction, and the first example of the construction of a 3-azabicyclo[3,1,0]hexane through an intramolecular [3 + 2] cycloaddition/nitrogen extrusion.

A new series of Cd(ii) metal-organic architectures driven by soft ether-bridged tricarboxylate spacers: synthesis, structural and topological versatility, and photocatalytic properties.

Two multifunctional, ether-bridged tricarboxylic acids, 2-(4-carboxylphenoxy)terephthalic acid (H3cpta) and 2-(3,5-dicarboxylatobenzyloxy)benzoic acid (H3dbba), were used as unexplored and highly versatile building blocks for the hydrothermal generation of a novel series of cadmium(ii) metal-organic architectures. These were formulated as [Cd(µ-Hcpta)(phen)(py)]n (1), {[Cd3(µ5-cpta)2(phen)3]·8H2O}n (2), {[Cd3(µ5-cpta)2(2,2'-bipy)3]·6H2O}n (3), {[Cd(µ3-cpta)(Hbpa)]·2H2O}n (4), {[Cd6(µ4-cpta)2(µ6-cpta)2(H2biim)2(H2O)6]·5H2O}n (5), [Cd3(µ4-cpta)2(µ-prz)(H2O)4]n (6), {[Cd3(µ4-dbba)2(phen)3]·H2O}n (7), and {[Cd3(µ3-dbba)2(2,2'-bipy)3(H2O)3]·2H2O}n (8) on the basis of single-crystal X-ray diffraction, elemental analysis, FTIR, PXRD, and TGA data. Products 1-8 were assembled in the presence of N-donor crystallization mediators selected from pyridine (py), 1,10-phenanthroline (phen), 2,2'-bipyridine (2,2'-bipy), bis(4-pyridyl)amine (bpa), 2,2'-biimidazole (H2biim), or piperazine (prz). The nature of the crystallization mediator and/or the type of principal tricarboxylate building block have a significant effect on the structural diversity, dimensionality, and topology of the resulting cadmium-organic architectures. These span from 1D (1, 8) and 2D (7) coordination polymers to 3D metal-organic frameworks (2-6) with intricate topologies (3,4,5T64 in 2 and 3, utp (103)-d in 4, 3,4,4T9 in 6) that also include unprecedented types in 5 and 7. Besides, MOF 6 features a 3D + 3D two-fold interpenetrated framework. Luminescent and photocatalytic properties of selected materials were investigated, showing that coordination polymer 7 is a promising photocatalyst for the UV-light-driven degradation of methylene blue as a model organic dye pollutant. Moreover, products 7 and 8 are the first examples of structurally characterized coordination compounds derived from H3dbba.

Construction of the tetracyclic core of (±)-cycloclavine and 4-amino Uhle's ketone.

A rapid construction of the tetracyclic core (±)-2 of (±)-cycloclavine (1) was accomplished in seven steps and 24% overall yield from commercially available aldehyde 7. Key features include a domino Friedel-Crafts/nitro-Michael reaction to construct the C ring and an intramolecular ammonolysis of a diester to close the D ring. In addition, a versatile 4-amino Uhle's ketone (±)-3 was afforded rapidly in five steps and 43% overall yield.

A new series of Co, Ni, Zn, and Cd metal-organic architectures driven by an unsymmetrical biphenyl-tricarboxylic acid: hydrothermal assembly, structural features and properties.

This study reports the hydrothermal synthesis of a novel series of twelve coordination compounds, namely, {[Cd(µ-Hnbtc)(H2O)4]·H2O}n (1), [Zn2(µ-Hnbtc)2(phen)2]·2H2O (2), [Zn(Hnbtc)(phen)2(H2O)]·4.5H2O (3), [Ni(Hnbtc)(phen)2(H2O)]·6H2O (4), [Zn2(µ-Hnbtc)2(2,2'-bipy)2]·2H2O (5), [Cd3(µ5-nbtc)(µ6-nbtc)(2,2'-bipy)2(H2O)]n (6), {[Zn3(µ3-nbtc)2(phen)3(H2O)2]·4H2O} (7), [Co(H2O)6][Co2(nbtc)2(µ-4,4'-bipy)(4,4'-bipy)2(H2O)6]·8H2O (8), {[Ni3(µ4-nbtc)2(µ-4,4'-bipy)2.5(µ-H2O)(H2O)3]·4H2O}n (9), {[Cd2(µ4-nbtc)(µ-OH)(2,2'-bipy)2]·H2O}n (10), [Cd2(µ4-nbtc)(µ-OH)(phen)2(H2O)]n (11), and {[Zn2(µ5-nbtc)(µ3-OH)(µ-4,4'-bipy)]·4,4'-bipy·H2O}n (12), which are derived from 3'-nitro-biphenyl-2,4,4'-tricarboxylic acid (H3nbtc) as a virtually unexplored building block. These compounds were generated in aqueous medium from the corresponding metal(ii) chlorides as a metal source, H3nbtc as a principal building block, NaOH as a base, and simple N,N-donor aromatic ligands as crystallization mediators (i.e., 1,10-phenanthroline, phen; 2,2'-bipyridine, 2,2'-bipy; or 4,4'-bipyridine, 4,4'-bipy). All products 1-12 were completely characterized in the solid state by IR spectroscopy, elemental and thermogravimetric (TGA) analyses, powder (PXRD) and single-crystal X-ray diffraction. Structures of 1-12 range from discrete 0D dimers (2 and 5) or monomers (3, 4, and 8) to 1D coordination polymers (CPs, 1, 6, 7, 10, and 11) and 3D metal-organic frameworks (MOFs, 9 and 12). A broad structural diversity of 1-12 is guided by the type of the metal(ii) node, the molar ratio between H3nbtc and sodium hydroxide, and the kind of crystallization mediator. Topological analysis and classification of metal-organic underlying nets was made, disclosing the following topological types: 2C1 (in 1 and 7), 1M2-1 (in 2 and 5), SP1-periodic net (in 10 and 11), tfz-d (in 12), and some topologically unique nets (in 6 and 9). Luminescence behavior of 1-3, 5-7, and 10-12 was studied in the solid state. Magnetic properties of a Ni(ii) MOF 9 were also investigated and modeled. All obtained products 1-12 represent the first structurally characterized examples of coordination compounds derived from H3nbtc, thus opening up its application in coordination chemistry as a novel tricarboxylate building block.

Asymmetric formal synthesis of (+)-cycloclavine.

The asymmetric synthesis of Szántay's amine (+)-2, the pivotal precursor for direct access to (+)-cycloclavine (1), is described for the first time in eleven steps with 19.7% overall yield from the commercially available 4-bromoindole. The strategy features an asymmetric induction by Ellman's sulfinimine and rhodium-catalysed isomerization of the C[double bond, length as m-dash]C bond.

4,5,9,10-Pyrene Diimides: A Family of Aromatic Diimides Exhibiting High Electron Mobility and Two-Photon Excited Emission.

The design and synthesis of high-performance n-type organic semiconductors are important for the development of future organic optoelectronics. Facile synthetic routes to reach the K-region of pyrene and produce 4,5,9,10-pyrene diimide (PyDI) derivatives are reported. The PyDI derivatives exhibited efficient electron transport properties, with the highest electron mobility of up to 3.08 cm2 V-1 s-1 . The tert-butyl-substituted compounds (t-PyDI) also showed good one- and two-photon excited fluorescence properties. The PyDI derivatives are a new family of aromatic diimides that may exhibit both high electron mobility and good light-emitting properties, thus making them excellent candidates for future optoelectronics.

Hydrothermal assembly, structures, topologies, luminescence, and magnetism of a novel series of coordination polymers driven by a trifunctional nicotinic acid building block.

In this work, a trifunctional N,O-building block, 5-(4-carboxyphenoxy)nicotinic acid (H2cpna), that combines three distinct types of functional groups (COOH, N-pyridyl, and O-ether) was used for the hydrothermal assembly of thirteen new coordination compounds: [Co(µ3-Hcpna)2]n (1), [Mn(µ4-cpna)(H2O)]n (2), [Mn(µ4-cpna)(H2O)2]n (3), [Mn(µ-cpna)(2,2'-bipy)(H2O)2]n (4), {[Ni(µ3-cpna)(2,2'-bipy)(H2O)]2·H2O}n (5), {[Cd(µ3-cpna)(2,2'-bipy)]·2H2O}n (6), [Zn2(µ-cpna)2(2,2'-bipy)2] (7), [Cu(µ-cpna)(2,2'-bipy)(H2O)]n (8), {[Mn(µ-cpna)(phen)2]·6H2O}n (9), {[Ni(µ3-cpna)(phen)(H2O)]·H2O}n (10), [Zn2(µ-cpna)2(phen)2] (11), {[Pb(µ3-cpna)(phen)]·H2O}n (12), and [Ni(µ3-cpna)(4,4'-bipy)0.5(H2O)]n (13). These products were synthesized from the corresponding metal(ii) chlorides, H2cpna, NaOH, and optional N-donor supporting ligands or templates {bis(4-pyridyl)amine (bpa), 2,2'-bipyridine (2,2'-bipy), 4,4'-bipyridine (4,4'-bipy), or 1,10-phenanthroline (phen)}. Products 1-13 were characterized in the solid state by standard methods, including elemental and thermogravimetric analysis (TGA), IR spectroscopy, and powder (PXRD) and single-crystal X-ray diffraction. The structures of 1-13 feature distinct structural types, namely the 3D metal-organic frameworks (MOFs 1-3), the 2D coordination polymers (5, 6, 10, 12, and 13), the 1D coordination polymers (4, 8, and 9), and the 0D discrete cyclic dimers (7 and 11). Such a wide structural diversity of 1-13 is driven by various factors, including the type of the metal(ii) node, the deprotonation degree of H2cpna, and/or the type of supporting ligand or template. Notably, an addition of bpa can tune the structure of MOF 3 by the template effect. Topological classification of underlying metal-organic networks was performed, leading to several distinct topological nets: rtl (in 1), hxg-d-4-C2/m (in 2), sra (in 3), 2C1 (in 4, 8 and 9), fes (in 5, 10, and 12), hcb (in 6), and 3,4L83 (in 13). The magnetic behavior of 1-5, 8-10, and 13 was studied and theoretically modeled, disclosing antiferromagnetic interactions. The luminescence behavior of 6, 7, 11, and 12 was also investigated.

Total Synthesis of (-)-Chanoclavine I and an Oxygen-Substituted Ergoline Derivative.

An efficient and direct route to ergot alkaloid (-)-chanoclavine I (3) is described using the inexpensive compound (2R)-(+)-phenyloxirane (15) as a chiral pool in 13 steps with 17% overall yield. Key features of the synthesis include a palladium-catalyzed intramolecular aminoalkynylation of terminal olefin and a rhodium-catalyzed intramolecular [3 + 2] annulation. An oxygen-substituted ergoline derivative (-)-25 was also achieved by using the same strategy.

Pyrazine-fused isoindigo: a new building block for polymer solar cells with high open circuit voltage.

Pyrazine-fused isoindigo (PzIIG) was designed and synthesized as a novel electron acceptor to construct two D-A conjugated polymers, PzIIG-BDT2TC8 and PzIIG-BTT2TC10. Both the polymers were successfully applied in polymer solar cells, and the PzIIG-BDT2TC8 based solar cell device exhibited a PCE of 5.26% with a high Voc over 1.0 V.

Understanding the Halogenation Effects in Diketopyrrolopyrrole-Based Small Molecule Photovoltaics.

Two molecules containing a central diketopyrrolopyrrole and two oligothiophene units have been designed and synthesized. Comparisons between the molecules containing terminal F (FDPP) and Cl (CDPP) atoms allowed us to evaluate the effects of halogenation on the photovoltaic properties of the small molecule organic solar cells (OSCs). The OSCs devices employing FDPP:PC71BM films showed power conversion efficiencies up to 4.32%, suggesting that fluorination is an efficient method for constructing small molecules for OSCs.

Facile Preparation of α-Cyano-α,ω-Diaryloligovinylenes: A New Class of Color-Tunable Solid Emitters.

An efficient Knoevenagel condensation reaction was used to construct a series of α-cyano-α,ω-diaryloligovinylenes, which show prominent fluorescence emission in the solid state. On investigating the effect of conjugation length on fluorescent properties, we found that the diene structure showed superior solid-state luminescence. Furthermore, the emission color could be adjusted by introducing donor or acceptor functional groups at the terminal aryl groups. Full-color emission in the visible region can be achieved by adding different functional groups to the α-cyano-α,ω-diaryldivinylene moiety. The structure-property relationships were elucidated and some observations such as the substitution position effects were discussed. These compounds have potential applications as full-color solid emissive candidates in material science and their simple structures allow them to be easily modified resulting in further interesting properties.

Direct and short construction of the ACDE ring system of daphenylline.

Daphenylline, a novel daphniphyllum alkaloid, boasts a fused and bridging ring system coupled with six stereogenic centers. Here we present a direct and short construction of the ACDE ring system of daphenylline from the known 3-(2-bromophenyl)propanal in 10 steps and 17 % overall yield. The synthesis features an iron(III)-catalyzed aza-Cope-Mannich reaction, a self-terminating 6-exo-trig aryl radical-alkene cyclization and an intramolecular Friedel-Crafts acylation.

Construction of fused- and spiro-oxa-[n.2.1] skeletons by a tandem epoxide rearrangement/intramolecular [3+2] cycloaddition of cyclopropanes with carbonyls.

A Lewis acid promoted tandem reaction of epoxide rearrangement and intramolecular [3+2] cycloaddition reaction of cyclopropanes with carbonyls formed by epoxide rearrangement in situ, which were obtained with difficulty by a general method, is reported. A wide variety of fused- and spiro-oxa-[n.2.1] skeletons could be efficiently constructed.

Pentacenobis(thiadiazole)dione, an n-type semiconductor for field-effect transistors.

A new heteroacenequinone, pentaceno[2,3-c:9,10-c']bis([1,2,5]thiadiazole)-6,13-dione (PBTDQ), with two peripheral thiadiazole rings was synthesized, and its solid-state properties were characterized. The fused planar structure with a low-lying LUMO and low reorganization energy facilitates electron transport, affording µe values of up to 0.11 cm(2) V(-1) s(-1) in field-effect transistor devices.

Formal synthesis of (±)-cycloclavine.

An efficient formal synthesis of (±)-cycloclavine is achieved in seven steps and 27% overall yield from the known 2-(4-bromo-1-tosyl-1H-indol-3-yl)acetaldehyde. Key features include an iron(III)-catalyzed aza-Cope-Mannich cyclization and an intramolecular Heck reaction or a self-terminating 6-exo-trig aryl radical-alkene cyclization.

Synthesis of polyisoprene terpenoid dendrons and their applications in oligo(phenylene ethynylene)s as "shells".

The novel double-stage convergent synthesis of a new class of polyisoprene terpenoid (PIPTP) dendrons is described. PIPTP dendrons bear a highly branched aliphatic hydrocarbon skeleton and a hydrophilic hydroxy focal point functionality. These dendrons have the specific formula C((5×2)(G+1)(-5))H((5×2)(G+2)(-8))O, and each dendritic layer is constructed from an isoprene unit. The key branching steps involve a double alkyl-metal addition to an ester functionality, followed by deoxygenation of the resulting tertiary alcohol by triethylsilane and trifluoroacetic acid, then hydrogenation or hydrogenolysis. The dendrons were also attached to oligo(phenylene ethynylene)s (OPEs) so as to function as protective shells to allow fine tuning of the nanoscopic environment around the OPE moiety, and to exert precise control of the packing density and intermolecular interaction between the OPE cores. Fluorescence quantum yield data reveal that the OPE core is better encapsulated by the PIPTP dendrons than by Fréchet dendrons.

Single-wing extended tribenzotriquinacenes via bowl-shaped dehydrobenzene and isobenzofuran tribenzotriquinacene derivatives.

Monoaryne and monoisobenzofuran analogues of a C(3v)-symmetrical tribenzotriquinacene (TBTQ) were generated in situ and trapped with various dienes and dienophiles, respectively. In this way, a series of single-wing extended TBTQ derivatives bearing the bowl-shaped TBTQ unit in different topographical expositions have become accessible. This includes some novel tribenzotriquinacene "dimers", in which two TBTQ bowls are attached in syn- or anti-orientation at the terminal positions of rigid linker units. Several of these compounds have been characterized by both spectroscopy and X-ray structural analysis. The efficient access to the TBTQ "dimers" may lay a useful foundation for further studies of novel container compounds and supramolecular architectures.