Asymmetric control in Diels–Alder cycloadditions of chiral 9-aminoanthracenes by relay of stereochemical information

Synthesis and characterization of β,β′-dimethylated dithieno[3,2-b:2′,3′-d]pyrroles and their corresponding regioregular conducting electropolymers

Synthesis, structural characterization, and oxidative polymerization of β,β′-dimethyl-dithienopyrrole 2–7 leading to linear, strictly regioregular conjugated polymers without structural defects due to the blocked β-positions are described.

Preparation of a large-sized highly flexible carbon nanohoop

A highly flexible carbon nanohoop composed of HBC panels was prepared by connection together with biphenylene spacers.

Evaluating hydrogen bonding control in the diastereoselective Diels-Alder reactions of 9-(2-aminoethyl)-anthracene derivatives

Several 9-(2-aminoethyl)anthracene derivatives were prepared with different nitrogen substitutents including alkyl, acetamide, trifluoroacaeamide and t-butyl carbamate. The selectivity in Diels-Alder cyclodaddition reaction with N-methyl maleimide was evaluated through single crystal X-ray analysis of the products. Models for the change in selectivity with hydrogen bond acceptor are proposed, supported by DFT level calculations.

Cyclisation reactions of N-cinnamoyl-9-aminoanthracenes

N-Cinnamoyl-9-aminoanthracenes cyclise with PPA or triflic acid to form novel 2-azahexacyclo[10.6.6.0(1,5).0(6,11).0(13,18).0(19,24)]tetracosa-6(11),7,9,13,15,17,19(24),20,22-nonaen-3-ones. In contrast, both N-cinnamoyl-N-methyl-9-(2-aminomethyl)anthracene and N-cinnamoyl-9-(2-aminoethyl)anthracene undergo an intramolecular Diels-Alder cycloaddition.

Chiral aminophosphines as catalysts for enantioselective double-Michael indoline syntheses

The bisphosphine-catalyzed double-Michael addition of dinucleophiles to electron-deficient acetylenes is an efficient process for the synthesis of many nitrogen-containing heterocycles. Because the resulting heterocycles contain at least one stereogenic center, this double-Michael reaction would be even more useful if an asymmetric variant of the reaction were to be developed. Aminophosphines can also facilitate the double-Michael reaction and chiral amines are more readily available in Nature and synthetically; therefore, in this study we prepared several new chiral aminophosphines. When employed in the asymmetric double-Michael reaction between ortho-tosylamidophenyl malonate and 3-butyn-2-one, the chiral aminophosphines produced indolines in excellent yields with moderate asymmetric induction.

Bulk heterojunction photovoltaics using broadly absorbing small molecules based on 2-styryl-5-phenylazo-pyrrole

Three new soluble small molecules (B, B6, and A) with a low band gap based on 2-styryl-5-phenylazo-pyrrole were synthesized. Molecules B and B6 contained pyrrole and N-hexylpyrrole, respectively, as the central unit, which was connected to N,N-dimethylphenyl-4-azo on one side of the pyrrole molecule. Molecule A contained N-hexylpyrrole as the central unit, which was connected to anthracenyl-9-azo on one side of the pyrrole molecule. The other side of the pyrrole molecule was connected to cyanovinylene 4-nitrophenyl for all molecules. The long-wavelength absorption maximum of the molecules was located at 601-637 nm, and their optical band gap was 1.62-1.67 eV. The photovoltaic properties have been investigated using blends of B, B6, or A with PCBM, and it was found that the device based on A:PCBM had a higher power conversion efficiency (PCE) (2.06%) than the devices based on B:PCBM (1.33%) and B6:PCBM (1.36%). This has been attributed to the higher hole mobility, the lower band gap of A relative to that of B or B6, and the higher energy difference between the LUMO of A and PCBM. The effect of solvent annealing and thermal-solvent annealing on the photovoltaic response of the device based on the A:PCBM blend has been investigated, and it was found that the devices based on solvent-treated and subsequent thermally annealed blends have PCEs of 2.56 and 2.83%, respectively. The increase in the PCE has been attributed to the enhanced crystallinity of the blend and the improvement in the charge transport due to a reduction in the difference between the electron and hole mobility in the blend.

Enantioselective syntheses of candenatenins B and C using a chiral anthracene auxiliary

An asymmetric synthesis of two anticancer natural products, candenatenins B and C, is described, leading to a revision of the originally assigned stereochemistry. The synthesis follows a Diels-Alder/retro-Diels Alder strategy using a chiral anthracene auxiliary to access both targets with 90% ee. The inherent structural qualities of the auxiliary allow for both regio- and diastereoselective transformations.