Stereodivergent‐at‐Metal Synthesis of [60]Fullerene Hybrids

Chiral fullerene–metal hybrids with complete control over the four stereogenic centers, including the absolute configuration of the metal atom, have been synthesized for the first time. The stereochemistry of the four chiral centers formed during [60]fullerene functionalization is the result of both the chiral catalysts employed and the diastereoselective addition of the metal complexes used (iridium, rhodium, or ruthenium). DFT calculations underpin the observed configurational stability at the metal center, which does not undergo an epimerization process.     

Liquid‐Crystalline Mixed [5 : 1]Hexa‐adducts of [60]Fullerene. Preliminary Communication

A liquid‐crystalline mixed [5 : 1]hexa‐adduct of [60]fullerene was synthesized by addition of two different malonate derivatives onto C₆₀. The hexa‐adduct derivative 2 was prepared by a stepwise synthetic procedure (fullerene→mono‐adduct of C₆₀→hexa‐adduct of C₆₀). Cyanobiphenyl and octyloxybiphenyl derivatives were selected as mesogens. The malonate derivatives showed either a monotropic nematic phase or a monotropic smectic A phase, and the hexa‐adduct derivative gave rise to an enantiotropic smectic A phase.     

Regioselective Electrosynthesis of Rare 1,2,3,16‐Functionalized [60]Fullerene Derivatives

Fullerene derivatives with different addition patterns exhibit different physical, chemical, and biological properties, which are important for fullerene applications. Novel and rare 1,2,3,16‐functionalized [60]fullerene derivatives having a five‐membered heterocycle fused to a [5,6]‐junction were obtained with high regioselectivity by electrochemical derivatization of a [60]fulleroindoline. The product structures were determined by spectroscopic data and single‐crystal X‐ray analysis. The obtained high regioselectivity was rationalized using theoretical calculations.     

Supramolecular [60]Fullerene Liquid Crystals Formed By Self‐Organized Two‐Dimensional Crystals

Fullerene‐based liquid crystalline materials have both the excellent optical and electrical properties of fullerene and the self‐organization and external‐field‐responsive properties of liquid crystals (LCs). Herein, we demonstrate a new family of thermotropic [60]fullerene supramolecular LCs with hierarchical structures. The [60]fullerene dyads undergo self‐organization driven by π–π interactions to form triple‐layer two‐dimensional (2D) fullerene crystals sandwiched between layers of alkyl chains. The lamellar packing of 2D crystals gives rise to the formation of supramolecular LCs. This design strategy should be applicable to other molecules and lead to an enlarged family of 2D crystals and supramolecular liquid crystals.     

Design,Synthesis, and Self‐Assembly Behavior of Liquid‐Crystalline Bis‐[60]Fullerodendrimers

Bis‐[60]fullerodendrimers were synthesized by assembling [60]fullerene‐containing type I (terminal olefin) and type II (α,β‐unsaturated carbonyl olefin) olefins through the olefin cross‐metathesis reaction. The synthetic modular approach developed in this study allowed the preparation of mono‐[60]fullerodendrimers and their [60]fullerene‐free analogues. First‐ and second‐generation poly(aryl ester) dendrons carrying cyanobiphenyl mesogens were used as liquid‐crystalline promoters. The liquid‐crystalline properties were studied by polarized optical microscopy, differential scanning calorimetry, and small‐angle X‐ray scattering. In agreement with the nature and structure of the dendrimers, nematic, smectic, and multisegregated lamellar phases were observed. Owing to its versatility and tolerance towards many functional groups, olefin cross‐metathesis proved to be a reaction of choice for the elaboration of molecular materials with complex architectures.     

Spiro[pyrido[3,2,1‐ij]pyrimido[4,5‐b]quinoline‐7,5′‐pyrrolo[2,3‐d]pyrimidines] and Spiro[pyrimido[4,5‐b]quinoline‐5,1′‐pyrrolo[3,2,1‐ij]quinolines] Derived from 5,6‐Dihydro‐4H‐pyrrolo[3,2,1‐ij]quinoline‐1,2‐dione

Reaction of 5,6‐dihydro‐4H‐pyrrolo[3,2,1‐ij]quinoline‐1,2‐dione ( 1 ) with two equivalents of some 6‐aminouracils (or 6‐amino‐2‐thiouracil) generates spirocyclic tetrahydrobenzo[if]quinolizines ( 7 ). The one‐pot, three‐component reaction of amido ketone ( 1 ) with 6‐aminouracil (or 6‐amino‐2‐thiouracil) and a cyclic six‐membered 1,3‐diketone produces spirocyclic tetrahydropyrrolo[3,2,1‐ij]quinolinones ( 15 ).     

Crystal‐Packing Trends for a Series of 6,9,12,15,18‐Pentaaryl‐1‐hydro[60]fullerenes

The relationship between the size of the substituents of aryl groups in a series of fifteen 6,9,12,15,18‐pentaaryl‐1‐hydro[60]fullerenes and the solid‐state structures and packing motifs of these compounds has been analyzed. Pentaarylfullerenes have a characteristic “badminton shuttlecock” shape that causes several derivatives to crystallize into columnar stacks. However, many pentaarylfullerenes form non‐stacked structures with, for example, dimeric, layered, diamondoid, or feather‐in‐cavity relationships between molecules. Computational modeling gave a qualitative estimate of the best shape match between the ball and socket surfaces of each pentaarylfullerene. The best match was for pentaarylfullerenes with large, spherically shaped para‐substituents on the aryl groups. The series of pentaarylfullerenes was characterized by single‐crystal X‐ray diffraction. A total of 34 crystal structures were obtained as various solvates and were categorized by their packing motifs.     

Synthesis of substituted pyrimido[4,5‐b] and [5,4‐c]‐[1,8]naphthyridines

Ethyl 1‐ethyl‐7‐methyl‐4‐oxo‐1,4‐dihydro[1,8]naphthyridine‐3‐carboxylate ( 1 ), precursor of nalidixic acid, has been converted in two steps through ([1,8]naphthyridin‐3‐yl)carbonylguanidine derivatives into substituted pyrimido[4,5‐b] and [5,4‐c][1,8]naphthyridines.     

Three‐Component Reaction for Construction of Spiro[indoline‐3,7′‐thiazolo[3,2‐a]pyridines] and Spiro[benzo[4,5]thiazolo[3,2‐a]pyridine‐3,3′‐indolines]

The three‐component reaction of thiazole (benzothiazole), dialkyl but‐2‐ynedioate, and isatinylidene malononitriles in toluene at 110–120°C in a sealed tube afforded a mixture of cis/trans‐isomers of functionalized diastereoisomeric spiro[indoline‐3,7′‐thiazolo[3,2‐a]pyridines] and spiro[benzo[4,5]thiazolo[3,2‐a]pyridine‐3,3′‐indolines] in good yields. Both cis‐isomers and trans‐isomers were successfully separated out and fully characterized with spectroscopy and single crystal determination. Under similar conditions, the three‐component reaction containing 2‐(1,3‐dioxo‐1H‐inden‐2(3H)‐ylidene)malononitrile resulted in spiro[indene‐2,7′‐thiazolo[3,2‐a]pyridine] derivatives.     

Synthesis of Tetrahydrothiopyrano[2,3‐b]indole [60]Fullerene Derivatives via Hetero‐Diels–Alder Reaction of C60 and α,β‐Unsaturated Indole‐2‐thiones

Hetero‐Diels–Alder reactions of [60]fullerene with α,β‐unsaturated thio‐oxindoles ( 3a , 3b , 3c ), prepared from thio‐oxindole 1 and heteroaromatic aldehydes ( 2a , 2b , 2c ), to generate tetrahydrothiopyrano[2,3‐b ]indole [60]fullerene cycloadducts ( 5a , 5b , 5c ) under thermal or microwave irradiation were described. The yields were improved, and the reaction time was decreased by conducting the reaction under microwave irradiation.     

[60]Fullerene-flavonoid dyads

A range of fullerene-chalcone, fullerene-flavone, and fullerene-chromone dyads, including a bis(flavonyl)-fullerene dyad, were prepared by 1,3-dipolar cycloaddition reactions of azomethine ylides to C₆₀ and by cyclopropanation of C₆₀ with flavonyl malonates. Synthetic and natural flavonoid derivatives were used as starting materials.     

Synthesis of new benzo[h]‐ and benzo[f]chromeno[2,3‐b]‐pyridine‐5‐ones

A number of new benzo[h]‐ and benzo[f]chromeno[2,3‐b] pyridine‐5‐ones derivatives were synthesized from benzo[h]‐ and benzo[f]‐chromone‐carbonitriles and amino‐benzo[h]‐ and benzo[f]chromone‐carbaldehydes. © 2006 Wiley Periodicals, Inc. Heteroatom Chem 17:2–7, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20152     

2,5‐Dimethyl‐6,7‐dihydrobenzo[h]pyrazolo[1,5‐a]quinazoline and 2‐tert‐butyl‐5‐methyl‐6,7‐dihydrobenzo[h]pyrazolo[1,5‐a]quinazoline

In both 2,5‐dimethyl‐6,7‐dihydrobenzo[h]pyrazolo[1,5‐a]quinazoline, C₁₆H₁₅N₃, (I), and 2‐tert‐butyl‐5‐methyl‐6,7‐dihydrobenzo[h]pyrazolo[1,5‐a]quinazoline, C₁₉H₂₁N₃, (II), which crystallizes with Z′ = 2 in the space group P, the non‐aromatic carbocyclic rings adopt screw‐boat conformations. The molecules of (I) are linked into chains of rings by a combination of C—H...N and C—H...π(arene) hydrogen bonds, while in (II) there are no hydrogen bonds of any kind.     

Structural Transformation of Methoxy‐Substituted Benzo[de]benzo[4,5]imidazo[2,1‐a]isoquinolin‐7‐ones

Structural transformation of two methoxy derivatives of benzo[de]benzo[4,5]imidazo[2,1‐a]‐isoquinolin‐7‐one were determined via spectroscopic analysis. The transformation mechanism was proposed as the breakage and reformation of the lactam bond.