Intramolecular Friedel-Crafts Cyclization Research Articles

Intramolecular friedel‐crafts cyclization and subsequent hydrogenation of styrene‐isoprene random copolymers prepared by anionic polymerization for thermally‐resistant and optical applications

AbstractTo synthesize novel thermally and optically high‐performing thermoplastics from commodity monomers, random styrene (St)‐isoprene (Ip) rubbers (r‐SIRs) prepared by anionic copolymerization were subjected to intramolecular Friedel‐Crafts cyclization and subsequent hydrogenation via a sequence of simple postpolymerization modifications. The CF3SO3H‐catalyzed Friedel‐Crafts alkylation of r‐SIR afforded cyclized r‐SIR (C‐r‐SIR) via the predominant formation of bicyclic tetrahydronaphthyl units to give thermoplastics with a high glass transition temperature (Tg ∼130 °C), good mechanical properties, and good transparency. Subsequent hydrogenation of the small amount of remaining CC double bonds in the uncyclized Ip units and cyclized Ip‐Ip units yielded hydrogenated C‐r‐SIR (HC‐r‐SIR) and increased the degradation temperature by about 15 °C (Td5 ≥ 380 °C). These HC‐r‐SIRs display good flexural moduli and strength, good transparency, and refractive indices similar to those of C‐r‐SIR. The birefringence of HC‐r‐SIR was successfully tuned by adjusting the comonomer content to obtain near‐zero birefringence high‐performance plastics. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

Random copolymer of styrene and diene derivatives via anionic living polymerization followed by intramolecular Friedel–Crafts cyclization for high-performance thermoplastics

Rubbery random copolymers of styrenes and dienes prepared via anionic living polymerizations were intramolecularly cyclized into high-performance thermoplastics.

Synthesis of Multisubstituted Indenes by Fe(III)-Catalyzed Friedel-Crafts Cyclization of Allylic Alcohols

FeCl 3•6H2O-catalyzed intramolecular Friedel-Crafts cyclization of multisubstituted allylic alcohols proceeded smoothly and a series of multisubstituted indenes were synthesized in moderate to high yields. The reaction has the advantages of simple manipulation and mild reaction conditions. The products were characterized by IR, 1 H NMR, 13 C NMR, HR MS and

Protecting Group Free Formal Total Synthesis of the Antitubercular Agent Erogorgiaene

AbstractThe formal total synthesis of the antitubercular agent erogorgiaene was achieved in 12 steps by using a protecting group free strategy. The synthesis involves an enamine‐mediated 1,4‐addition, an aldol condensation, dehydrogenation, Wittig olefination, intramolecular Friedel–Crafts cyclization, TEMPO‐BAIB‐mediated oxidation, and Evans auxiliary based diastereoselective methylation.

Synthesis of tetrahydrobenzoisoquinolinols, tetrahydropyrindines, and hexahydroquinolines from 4-aryltetrahydropyridines

A straightforward synthesis of tetrahydrobenzoisoquinolinols 2, tetrahydropyrindines 3, and hexahydroquinolines 4 from versatile intermediate 6 is reported. Two key transformations were carried out by intramolecular Friedel–Crafts cyclization and ring-closing metathesis in moderate yields. Skeleton 6 was easily prepared from the known starting material 4-aryl-4-methoxypiperidin-3-ones 7 via Wittig olefination with Ph 3P=CHCO 2Et, deconjugation with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU), and boron trifluoride etherate (BF 3–OEt 2)-catalyzed addition of the corresponding iminium ion with allyltrimethylsilane.

ChemInform Abstract: Montmorillonite K‐10 Catalyzed Cyclization of N‐Ethoxycarbonyl‐N′‐arylguanidines: Access to Pyrimido[4,5‐c]carbazole and Pyrimido[5,4‐b]indole Derivatives.

AbstractTwo new heterocycles (IV) and (VII) are prepared in three steps using a montmorillonite K‐10‐catalyzed intramolecular Friedel—Crafts cyclization as key reaction.

Synthesis of substituted ( S)-2-aminotetralins via ring-opening of aziridines prepared from l-aspartic acid β- tert-butyl ester

This paper describes the total synthesis of the hydrochloride salts of (2 S)-2-amino-7-methoxytetralin ( 21- HCl) and (2 S)-2-amino-6-fluoro-7-methoxytetralin ( ST1214), from a common enantiomerically pure aziridine 4b, which was available from l-aspartic acid β- tert-butyl ester. The synthesis of 21- HCl and ST1214 proceeded in nine steps and 5 and 6% overall yields, respectively. Key steps are the regioselective ring-opening of 4b with ArMgBr/CuBr·SMe 2 and the intramolecular Friedel–Crafts cyclisation providing α-tetralone. Substituted naphthalenes were formed as side products in the latter reaction.

Low Band Gap Polymers Having Multi-Fused Heterocycles

The authors reported the synthesis and characterization of novel D-A-type copolymers that consist of a heptacyclic donor and 2,1,3-benzothiadiazole as an acceptor. The core structure of the ladder-type monomer can be efficiently assembled by Brønsted acid mediated intramolecular Friedel-Crafts cyclization. It is noteworthy that the synthesized polymers show good solubility to common organic solvents, lower band gaps than those of corresponding non-fused polymers, and high hole mobilities. Furthermore, the authors demonstrated the validity of the polymers by fabricating bulk heterojunction (BHJ) solar cells, which exhibit high power conversion efficiencies (PCE) of 2.8% for P1 and 3.7% for P2, ­respectively.

Iodine/Et 3SiH: a novel reagent system for the synthesis of 3-aryl-1 H-indenes from 1,3-diaryl propargyl alcohols

1,3-Diaryl propargyl alcohols undergo smooth intramolecular Friedel–Crafts cyclization with triethylsilane in the presence of 10 mol % iodine 3-aryl-1 H-indene derivatives in good yields in short reaction times. This is the first example on the synthesis of substituted indenes from 1,3-diaryl propargyl alcohols. The use of inexpensive and readily available molecular iodine makes this method quite simple, more convenient, and practical.

ChemInform Abstract: Synthesis of New Diversely Linked Biquinoline Derivatives by Multicomponent Imino‐Diels—Alder Cycloaddition and Intramolecular Friedel—Crafts Cyclization.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Synthesis of 1-Azaxanthones and 1-Azathioxanthones by Yb(OTf)3/TfOH Co-Catalyzed Intramolecular Friedel-Crafts Reaction

Intramolecular Friedel-Crafts cyclization of phenoxypyridine acids (3a-3j) and phenythiopyridine acids (4a-4i) to form 1-azaxanthones (1a-1j) and 1-azathioxanthones (2a-2i), respectively, was efficiently promoted by Yb(OTf) 3 /TfOH as co-catalysts. And a number of substrates could be cyclized in moderate to good yields.

Synthesis of New Diversely Linked Biquinoline Derivatives by Multicomponent Imino-Diels-Alder Cycloaddition and Intramolecular Friedel-Crafts Cyclization

New and efficient routes for diversely linked 2,6¢-, 2,7¢-, 2,2¢-, or 2,8¢-biquinoline derivatives are reported. These routes are based on the powerful methodologies of imino-Diels–Alder cycloaddition reactions and intramolecular Friedel–Crafts cyclization reactions.

Efficient synthesis of indenes by FeCl 3·6H 2O-catalyzed intramolecular Friedel–Crafts reaction of aryl-substituted allylic alcohols

An efficient procedure for the synthesis of substituted indenes through the FeCl 3·6H 2O-catalyzed intramolecular Friedel–Crafts cyclization of aryl-substituted allylic alcohols has been developed. This method features the easily available starting materials, cheap catalyst, simple manipulation, and mild conditions.

Synthesis of 3,4-disubstituted 2(1 H)-quinolinones via intramolecular Friedel–Crafts reaction of N-arylamides of Baylis–Hillman adducts

3,4-Disubstituted 2(1 H)-quinolinones were synthesized starting from the Baylis–Hillman adducts via the following sequential processes: (i) hydrolysis of the Baylis–Hillman adduct to acid, (ii) EDC coupling with anilines, (iii) H 2SO 4-assisted intramolecular Friedel–Crafts cyclization, and the final (iv) DBU-mediated isomerization.

Remarkably Mild and Efficient Intramolecular Friedel—Crafts Cyclization Catalyzed by In(III).

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Efficient Intramolecular Friedel-Crafts Cyclization of Allylic Halides

In(III) salts were found to be specific and robust catalysts for intramolecular Friedel-Crafts cyclization of allylic bromides. This is a simple method for the annelation of a six-membered ring, which may bear a heteroatom or a functional group. The conditions are remarkably mild and the substrate scope is relatively broad, including deactivated arenes. A unique catalytic activity of indium salts in this reaction may lead to the development of new useful catalytic methods with their participation.

Remarkably mild and efficient intramolecular Friedel-Crafts cyclization catalyzed by In(III).

[structure: see text]. Indium(III) salts were found to be highly effective catalysts for the intramolecular Friedel-Crafts reaction of simple allylic bromides and arenes. In(III) salts appear to be the most general and possess unique halophilic properties as a Lewis acid for this reaction among the catalysts evaluated to date. Deactivated arenes possessing chloride, bromide, and fluoride underwent smooth reaction when activated by InCl3.

Synthesis of 1,1‐Dimethyl‐4‐indanol Derivatives.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.

Synthesis of 1,1‐Dimethyl‐4‐indanol Derivatives

The synthesis of 1,1‐dimethyl‐4‐indanols (3a,b) has been achieved by intramolecular Friedel–Crafts cyclization of 2‐(3‐methyl‐2‐butenyl)phenols (5a,b) or 1‐methoxy‐2‐(3‐methyl‐2‐butenyl)benzenes (6a,b) followed by demethylation, respectively.It was found that the solvent was critical for the formation of different products in the intramolecular Friedel–Crafts reactions of 6. The unexpected product 4‐methoxy‐1,1,6,6‐tetramethyl‐as‐hydrindacene (11) was obtained from the Friedel–Crafts reactions of 6a, and its structure was confirmed by X‐ray diffraction analysis. The key intermediates 5a,b were prepared by ortho‐alkenylation of phenols with 1‐bromo‐3‐methyl‐2‐butene, and the reaction temperature exerted an obvious impact on the yield of 2‐(3‐methyl‐2‐butenyl)phenol (5a).

Synthesis and characterization of a helical step‐ladder polyarylene

AbstractA helical step‐ladder polyarylene incorporating chiral (R)‐2,2′‐dioctoxy‐1,1′‐binaphthyl units was synthesized for the first time. The first step involved the preparation of a precursor poly(arylene ketone) via a palladium‐mediated Suzuki‐type cross‐coupling reaction with the aid of microwave heating. Two polymer‐analog reaction steps, the reduction of the keto groups to tertiary alcohol functionalities and subsequent intramolecular Friedel–Crafts cyclization, gave a step‐ladder polymer (6) in good yields with reasonable mean average molecular weights greater than 13,000. The regioselective cyclization pattern in the α position of the naphthalene core was confirmed by a comparison of the NMR data of the polymer with those of the corresponding model ladder oligomers, 12 and 13, and also a single‐crystal structure of 13. The optical spectra of the oligomers and polymers indicated that there was little electronic interaction across the binaphthyl units. The circular dichroism spectrum of 6 exhibited a strong bisignate Cotton effect in the π–π* absorption region of the planar chromophores, which reflected the strong exciton coupling within the helical polymer chain. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5533–5545, 2006