Efficient organocatalyzed solvent-free selective synthesis of conjugated enones

A series of conjugated dienones and enones were synthesized by a reaction of both conjugated and simple aldehydes, respectively, with 1,3-dicarbonyl compounds and aldehydes under solvent-free conditions at room temperature in the presence of 10 mol % of l-proline as catalyst. The selective formation of one isomer was observed exclusively with most of the 1,3-dicarbonyl compounds and aldehydes. The most commonly formed xanthene derivative from the cyclic diketones is inhibited with our protocol, with the exclusive formation of conjugated dienones only.     

First synthesis of the bismole‐containing conjugated polymer

We successfully synthesized the first conjugated polymer containing a bismuth atom in the conjugated main chain by incorporating a bismuth atom into the cyclopentadiene framework (bismole), which was constructed by a polymer reaction. A synthetic procedure and characterization of the obtained polymers were discussed. This bismole‐containing conjugated polymer exhibited moderate bluish green photoluminescence in solution. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4857–4863, 2006     

Practical,high-yield synthesis of thiol-terminated diacetylenes for formation of conductive monolayers

Self-assembled monolayers of thiol terminated conjugated diacetylenes can be cross-linked using ultraviolet light to form highly conjugated polydiacetylenic conductive monolayers [1]; however, the reported syntheses of the diacetylene monomers present numerous problems that prevent the wide spread application of these in functional materials. We report a redesigned four-step synthesis that proceeds in 75–80% overall yields and allows gram scale production of an array of thiol terminated conjugated diacetylenes, thereby allowing examination and application of these low-dimensional conductive materials.     

Design and synthesis ethynyl ferrocene-based multifunctional chemosensors for fluoride anion

Research on Chemical Intermediates - To exploit novel ferrocene-based small molecules with long conjugated structures as visible and electrochemical multichannel chemosensors, four conjugated...     

Practical synthesis of 1,5-dimethyl substituted conjugated polyenes from geranyl acetate

A protocol to synthesize 1,5-dimethyl substituted conjugated polyenes via dehydrogenation of geranyl acetate was established. C₅ unit elongation to multi-1,5-dimethyl substituted conjugated polyenes was also achieved via Horner-Wadsworth-Emmons olefination in good yields and good selectivities.     

Total synthesis of gambierol

[structure: see text] The first total synthesis of gambierol, a marine polycyclic ether toxin, has been achieved. The synthesis features the Pd(PPh3)4/CuCl/LiCl-promoted Stille coupling for the stereoselective construction of the sensitive triene side chain that includes a conjugated (Z,Z)-diene moiety.     

Total synthesis of paracentrone, C31-allenic apo-carotenoid

The stereocontrolled total synthesis of a C31-allenic apo-carotenoid, paracentrone, was achieved by the convergent C20 + C11 = C31 strategy. The key elements of our synthesis were the Pd-catalyzed cross-coupling to stereoselectively construct the conjugated polyene backbone skeleton and the designed geometrical isomerization at the central double bond of the conjugated polyene chain. In addition, the terminal oxygenated cyclohexane ring having the allenic moiety was prepared by the highly diastereoselective Sharpless epoxidation under our own reaction conditions.     

Efficient synthesis of substituted dihydrotetraazapentacenes

We describe a versatile and very efficient synthesis of previously unknown substituted 5,14-dihydro-5,7,12,14-tetraazapentacenes (DHTAPs). A structural study by NMR spectroscopy showed that the conjugated pi-system of the pentacyclic skeleton rearranges depending on the electronic effect of the substituent(s).     

First synthesis of a series of core-modified tetrabenzoporphyrins

Successful synthesis of a series of highly conjugated porphyrin analogues, including thia-, dithia- and oxathia-tetrabenzoporphyrins, and their optical properties are reported.     

Electrochemical synthesis of polypyrrole in powder form

Journal of Solid State Electrochemistry - Novel approach to synthesis of conjugated oligomers/polymers is proposed. This approach combines all advantages of electrochemical methods: variation of...     

Expedient synthesis of conjugated triynes via alkyne metathesis

The first synthesis of conjugated triynes by molybdenum-catalysed alkyne metathesis is reported. Strategic to the success of this approach is the utilization of sterically-hindered diynes that allowed for the site-selective alkyne metathesis to produce the desired conjugated triyne products. The steric hindrance of the alkyne moiety was found to be crucial in preventing the formation of diyne byproducts. This novel synthetic strategy was amenable to self- and cross-metathesis providing straightforward access to the corresponding symmetrical and dissymmetrical triynes with high selectivity.

The first synthesis of symmetrical and dissymmetrical conjugated triynes by self- and cross-metathesis was successfully achieved thanks to the use of hindered diynes.     

Continuous flow synthesis of conjugated polymers

A selection of conjugated polymers, widely studied in organic electronics, was synthesised using continuous flow methodology. As a result of superior heat transfer and reagent control, excellent polymer molecular mass distributions were achieved in significantly reduced reaction times compared to conventional batch reactions.     

Highly diastereoselective synthesis of tetrahydrofurans via Lewis acid-catalyzed cyclopropane/aldehyde cycloadditions

A one-step procedure for the preparation of 2,5-disubstituted tetrahydrofurans from donor-acceptor cyclopropanes and aldehydes has been developed. In the presence of a catalytic amount of Sn(OTf)(2), cyclopropanes bearing an aryl or conjugated donor substituent vicinal to a malonyl diester group undergo cycloadditions with diverse conjugated aldehydes furnishing tetrahydrofurans with high cis diastereoselectivity. This method is useful for the preparation of regiodefined tetrahydrofurans.     

Gold(I)-catalysed synthesis of conjugated trienes

Gold(I)-catalysed reaction between cyclopropenes and furans produces functionalised conjugated trienes. The reaction is mild, facile and proceeds with very low catalyst loadings.     

Total synthesis of the Fusarium toxin equisetin

A short stereoselective synthesis of the Fusarium toxin equisetin, a potent inhibitor of HIV-1 integrase enzyme is described, using as the key step a stereoselective intramolecular Diels-Alder reaction of a fully conjugated E,E,E-triene with a trisubstituted gamma,delta-unsaturated beta-ketothioester.     

N-heterocyclic carbene enabled synthesis of conjugated polymers

The Suzuki polycondensation of a dihalogenated 4,5-diphenylimidazole (2) with a fluorenyl diboronic acid diester followed by methylation afforded a conjugated poly(imidazolium) copolymer (P2) in 93% yield. Upon exposure to strong base, P2 was converted in situ to the corresponding poly(N-heterocyclic carbene) P3, as evidenced by ¹H NMR spectroscopy and a trapping experiment involving sulfur that afforded the corresponding poly(thiourea) P4. Similarly, treating a solution of P2 with KOtBu and [Ir(1,5-cyclooctadiene)Cl]₂ afforded a conjugated polymer bearing pendant Ir complexes (P5) in 63% yield. Thermal and photophysical analyses of the aforementioned polymers revealed that they were thermally stable with tunable fluorescence properties, features which poise them for use in various electronic and sensing applications. The presented methodology is expected to facilitate the synthesis of a broad range conjugated organometallic polymers from a common and readily accessible precursor.     

Total synthesis of herboxidiene/GEX 1A

A convergent enantioselective synthesis of herboxidiene/GEX 1A (1) is described that features a double stereodifferentiating crotylation, [4 + 2] annulation, and a silicon-based sp2-sp2 cross-coupling to assemble the conjugated diene.     

Stereoflexible total synthesis of (−)-epiquinamide

Hydroxy propiolate rearrangement to conjugated diene, Sharpless asymmetric dihydroxylation and one-pot quinolizine construction have been used as key steps in the total synthesis of (−)-epiquinamide.     

Total synthesis of GEX1A

An efficient and readily modifiable synthesis of GEX1A/herboxidiene/TAN-1609 ( 1) was developed. This modular synthesis featured a Suzuki coupling to install the conjugated diene and a Ru-catalyzed lactonization and Roush crotylation to construct the functionalized tetrahydropyran moiety. Myers' alkylation, cross-metathesis, and Keck crotylation were employed for assembly of the biologically essential side-chain domain.     

Synthesis of lipoxins: Total synthesis of conjugated trihydroxy eicosatetraenoic acids

The first synthesis of a conjugated trihydroxy eicosatetraenoic acid, a possible structure for Lipoxin A is described. A biomimetic approach was utilized.