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Cyclization, intramolecular

A Rh(III)-catalyzed intramolecular redox-neutral or oxidative cyclization strategy for the rapid synthesis of 3,4-fused indole skeletons from tethered alkynes was [Pg.180]

Over the last decade, the rhodium-catalyzed C-H functionalization has emerged as a powerful approach for the synthesis of heterocycles, due to the obviation [Pg.181]

and Stang, P.J. (eds) (1998) Metal-Catalyzed Cross-Coupling Reactions, Wiley-VCH Verlag GmbH, [Pg.182]

For perspectives on atom, step, and redox economy, see (a) Trost, B.M. (1991) Science, 254, 1471-1477  [Pg.182]

For selected reviews on transition metal-catalyzed C-H activation, see  [Pg.182]


The intramolecular cyclization can be favored by (i) high dilution techniques, (ii) the action of a template which forces the reacting ends together, and (ill) stepwise condensations. [Pg.247]

Another interesting case is afforded by 2-alkyl-N-phenacyl or N-acetonylthiazolium salt (239), which in basic medium gives an intramolecular cyclization product. According to Reid et al. (502), this could... [Pg.141]

R = H) undergoes a variety of enzyme-catalyzed free-radical intramolecular cyclization reactions, followed by late-stage oxidations, eliminations, rearrangements, and O- and N-alkylations. Working from this generalization as an organizing principle, the majority of known AmaryUidaceae alkaloids can be divided into eight stmctural classes (47). [Pg.542]

Glycols may undergo intramolecular cyclization or cycHcaHy condense with other molecules to form a number of ring stmctures. Transesterification of carbonates with ethylene glycol produces ethylene carbonate [96-49-1] (eq. 4). Numerous materials catalyze carbonate transesterifications. [Pg.357]

The acid-instabihty of erythromycin makes it susceptible to degradation in the stomach to intramolecular cyclization products lacking antimicrobial activity. Relatively water-insoluble, acid-stable salts, esters, and/or formulations have therefore been employed to protect erythromycin during passage through the stomach, to increase oral bioavakabihty, and to decrease the variabiUty of oral absorption. These various derivatives and formulations also mask the very bitter taste of macroHdes. [Pg.98]

Another successhil strategy for derivatization of erythromycin employed modification of functional groups involved in intramolecular cyclizations. The C-9 ketone, C-6 hydroxyl group, C-8 proton, and/or C-ll,12-diol of erythromycin were converted into functional groups which participate poorly, if at all, in intramolecular cyclizations. Some derivatives which have been extensively evaluated in preclinical and clinical trials exhibit such desirable properties as better stabiUty under acidic conditions, greater oral bioavadabihty, and higher and more prolonged concentrations of antibiotic in semm and tissues. [Pg.100]

TL2733,82TL2737). The reaction proceeds through an aza-Cope rearrangement of the initially formed iminium salt, followed by intramolecular cyclization. [Pg.122]

In contrast to the above additions A-allyl- and substituted A-allyl-amides, -urethanes, -ureas and -thioureas undergo intramolecular cyclization only in 6(3-96% sulfuric acid to give the corresponding oxazolinium and thiazolinium salts. Treatment of these cations with base yields 2-oxazolines and 2-thiazolines in moderate to good yields. The reaction is illustrated by the conversion of A-2-phenylallylacetamide (342) into 2,5-dimethyl-5-phenyl-2-oxazoline (343) in 70% yield 70JOC3768) (see also Chapter 4.19). [Pg.141]

Ring contraction and intramolecular cyclization constitute a convenient route to ring-fused systems that would be difficult to synthesize in other ways. H- 1,2-Diazepines (538) undergo electrocyclic ring closure to the fused pyrazole system (539) (71CC1022). Azepines also undergo similar valence bond isomerizations. [Pg.161]

Some tricyclic systems have been prepared by intramolecular cyclization from A-aryl-pyrazoles carrying substituents both in the pyrazole ring at C-5 and in the phenyl ring at the o-position. Thus pyrazolo[l,5-n]quinazolines (563) (69JHC947) and pyrazolo[l,5-n]-[l,4]benzodiazepines (564) (77JHC1163, 77JHC1171) can be prepared from suitable precursors. [Pg.273]

A 1 1 adduct from diphenylsulfilimine and a benzoylacetylene underwent an intramolecular cyclization reaction to give an isoxazole in good yield (equation 40). Similarly, the 1 1 adduct from iodoazide and chalcone gave 3,5-diphenylisoxazole (equation 41). These two approaches to regiospecific isoxazole synthesis are of little practical significance. Additional examples of the (OCCCN) reaction are given in equations (42) and (43). [Pg.75]

Large ring heterocyclic radicals are not particularly well known as a class. Their behavior often resembles that of their alicyclic counterparts, except for transannular reactions, such as the intramolecular cyclization of 1-azacyclononan-l-yl (Scheme 1) (72CJCH67). As is the case with alicyclic ethers, oxepane in the reaction with r-butoxy radical suffers abstraction of a hydrogen atom from the 2-position in the first reaction step (Scheme 2) (76TL439). [Pg.19]

Preparative routes to aziridines and 1-azirines are derived from cycloelimination processes in which one, and sometimes two, bonds are formed directly to the nitrogen atom (Scheme 1). For aziridines these include the two intramolecular cyclization pathways involving either nucleophilic displacement by the amine nitrogen (or nitrenium anion) on the /3-carbon (route a) or nucleophilic displacement by a /3-carbanionic centre on the amine nitrogen... [Pg.80]

A series of amides has been prepared as protective groups that are cleaved by intramolecular cyclization after activation, by reduction of a nitro group, or by activation by other chemical means. These groups have not found much use since the first edition of this volume and are therefore only listed for completeness. The concept is generalized in the following scheme ... [Pg.356]

Many of the crown ether syntheses with which we are concerned in this book are one form or another of the Williamson ether synthesis. Although the simplest example of such a reaction would involve an co-haloethylene glycol oligomer which undergoes intramolecular cyclization, it is more common for two new bonds to be formed in crown syntheses. An early example of the formation of a crown by a double-Williamson can be found in Dale s synthesis of 18-crown-6. The rather obvious chemical steps are shown in Eq. (2.1). [Pg.12]

V-Perfluorophenylben7armde readily undergoes intramolecular cyclization to produce the benzoxazole system shown in equation 9 [13]... [Pg.502]

Intramolecular cyclization in perfluoroaromanc systems proves useful for the synthesis of heterocyclic compounds [72] For example, the Fischer indole synthesis, which normally requires the presence of an ortho proton, occurs satisfactonly with an ortho fluonne in theperfluoronaphthalene senes [73] (equation 37)... [Pg.512]

Benzotrithiadiazepine (12.14, R = H) is obtained as bright-yellow crystals by the reaction of benzo-l,2-bis(sulfenyl chloride) with McsSiNSNSiMcs (Eq. 12.4). The tetrafluoro derivative 12.14 (R = F) has been prepared by a similar procedure. The isomeric 1,2,4,3,5-benzotrithiadiazepine (12.15) is formed in the reaction of PhNSNSiMcs and S2CI2, followed by intramolecular cyclization (Eq. 12.5). " ... [Pg.247]

While esters do not usually react with enamines and can, in fact, be substituents in the azeotropic preparation of enamines, they can be used in acylation reactions when these involve intramolecular cyclizations. Such reactions have been observed even at room temperature when they lead to the formation of five- and six-membered vinylogous lactams (362). Applications to precursors for azasteroids (40S) and alkaloids (309,406) are key steps in synthetic sequences. [Pg.390]

Ammonia treatment removes the TFA group, which then releases the phosphate and pyrrolidine through intramolecular cyclization. The analogous pentyl derivative was also prepared. ... [Pg.671]

The intramolecular cyclization of A -acylated-o-alkylanilines in the presence of a strong base at elevated temperatures is known as the Madelung indole synthesis. ... [Pg.140]

The Pictet-Spengler reaction is an acid-catalyzed intramolecular cyclization of an intermediate imine of 2-arylethylamine, formed by condensation with a carbonyl compound, to give 1,2,3,4-tetrahydroisoquinoline derivatives. This condensation reaction has been studied under acid-catalyzed and superacid-catalyzed conditions, and a linear correlation had been found between the rate of the reaction and the acidity of the reaction medium. Substrates with electron-donating substituents on the aromatic ring cyclize faster than the corresponding unsubstituted compounds, supporting the idea that the cyclization process is involved in the rate-determining step of the reaction. [Pg.470]

Forty years after the initial proposal, Sweet and Fissekis proposed a more detailed pathway involving a carbenium ion species. According to these authors the first step involved an aldol condensation between ethyl acetoacetate (6) and benzaldehyde (5) to deliver the aldol adduct 11. Subsequent dehydration of 11 furnished the key carbenium ion 12 which was in equilibrium with enone 13. Nucleophilic attack of 12 by urea then delivered ureide 14. Intramolecular cyclization produced a hemiaminal which underwent dehydration to afford dihydropyrimidinone 15. These authors demonstrated that the carbenium species was viable through synthesis. After enone 13 was synthesized, it was allowed to react with N-methyl urea to deliver the mono-N-methylated derivative of DHPM 15. [Pg.510]

A modification of the K-R reaction was introduced by Mozingo. This method involved reacting an o-hydroxyacetophenone with an ester in the presence of metallic sodium to form a 1,3-diketone. Treatment of the diketone with an acid then delivered the chromone via an intramolecular cyclization reaction. This method was applied to the preparation of 2-ethylchromone (21). 0-hydroxyarylketone 22 was allowed to react with ethyl propionate (23) in the presence of sodium metal.The resulting sodium enolate was then quenched with acetic acid to deliver the 1,3-diketone 24. Upon heating 24 in glacial acetic acid and hydrochloric acid, 2-ethylchromone (21) was delivered in 70-75% overall yield. [Pg.524]

Three general approaches to the synthesis of pjTido[2,3-d]pyrimi-dines from pyrimidines are available, all of which utilize an appropriately substituted 4-aminopyrimidine. The pyridine ring may be formed by the addition of three (route i), or two (route ii) carbon atoms, or by the intramolecular cyclization of a propionyl derivative (route in). [Pg.160]

A variety of condensation processes can lead to cyclic hydroxamic acids. These involve either the condensation of two molecules or the intramolecular cyclization of a single compound. In some cases, a primary hydroxamic acid function is already present and formation of a cyclic compound can arise by suitable reaction on nitrogen. These processes will be dealt with first. [Pg.206]

The interesting work of Hahn and Hansel, who prepared a tetracyclic lactam by intramolecular cyclization of the condensation product of tryptamine and a-ketoglutaric acid, is referred to in Section IV, B, 2. Condensation of tryptamine with a,a -diketopimelic acid (403) led, presumably by way of the 1-substituted tetrahydro-)S-carboline (404), which could not be isolated, to a product to which the tetracyclic structure 405 was assigned. [Pg.180]


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1,3-Diketones, intramolecular oxidative cyclization

1.6- Enynes cyclization via intramolecular ene reaction

2 -Hydroxychalcones intramolecular cyclization

2- alkynylanilines intramolecular cyclization

A-Acyliminium ion cyclization intramolecular

Acetanilides intramolecular cyclization

Addition, intramolecular cyclization

Aldehydes intramolecular cyclization

Aldol condensation-intramolecular cyclization

Aldol-like intramolecular cyclization

Alkenes intramolecular cyclization

Alkylidene carbenes intramolecular cyclization

Alkynals intramolecular cyclization

Alkynes intramolecular cyclization with

Allenes intramolecular cyclizations

Allenes, cyclization intramolecular

Allenylidene intramolecular cyclization

Allylic derivatives intramolecular cyclization, carbonylative

Amides intramolecular cyclization

Amides intramolecular cyclization, carbonyl

Amidines intramolecular cyclization

Amino radicals) intramolecular cyclization

Anionic cyclization intramolecular carbolithiation

Anionic intramolecular Diels-Alder cyclization

Anti addition reactions intramolecular cyclization

Appendix to Chapter 23. Calculation of Maximum Possible Conversion for Intramolecular Cyclization Reactions

Aryl derivatives intramolecular cyclization

Aryl radical, intramolecular cyclization

Asymmetric intramolecular anionic cyclization

Azide cyclizations, intramolecular

Carbon-nitrogen bond forming reactions intramolecular cyclization

Carbonyl compounds intramolecular radical cyclization

Carbonylation intramolecular cyclization reactions

Carbopalladation intramolecular cyclization

Carboxylic acid derivatives, intramolecular cyclization reactions

Carboxylic acids intramolecular cyclization

Cyclization by Intramolecular Addition Reactions

Cyclization by intramolecular Claisen ester

Cyclization intramolecular Heck reaction, 2-halo

Cyclization intramolecular stereochemistry

Cyclization photochemical, intramolecular

Cyclization reactions intramolecular addition

Cyclization reactions intramolecular free

Cyclization reactions intramolecular oxidative

Cyclizations Intramolecular Conjugate Addition

Cyclizations intramolecular

Cyclizations intramolecular

Cyclizations intramolecular addition

Cyclizations intramolecular, aluminum-mediated

Cyclohexane derivatives intramolecular cyclization

Cyclopentanecarboxylates, 2-hydroxysynthesis via intramolecular Barbier cyclization

Decalins intramolecular cyclization of cyanocyclohexanes

Diels-Alder cyclization, intramolecular

Domino cyclization intramolecular carbopalladation

Double bond formation intramolecular cyclization

Endo cyclization intramolecular Heck reaction

Endo cyclization intramolecular carbopalladation

Enynes intramolecular cyclization

Erythromycin intramolecular cyclization

Esters intramolecular cyclization, carbonyl

Esters, 1,3-keto intramolecular Barbier cyclization

Esters, p-keto intramolecular Barbier cyclization

Friedel intramolecular cyclizations

Germacrones intramolecular cyclization

Heterocycles intramolecular anionic cyclization

Hydrindanes intramolecular cyclization of cyanocyclohexanes

Hydrogen atom transfer reactions intramolecular cyclization

Hydroxy aldehydes intramolecular cyclization

Imines intramolecular cyclization with

Iminium ions intramolecular cyclization

Indole derivatives intramolecular cyclizations

Intramolecular "aryl-Heck" cyclization

Intramolecular 5-exo and 6-endo Cyclization of Polyepoxides

Intramolecular Bradsher cyclization

Intramolecular Cascade Cyclizations

Intramolecular Cyclizations Involving Anion Radicals

Intramolecular Free Radical Cyclizations

Intramolecular Friedel-Crafts cyclization

Intramolecular Friedel-Crafts-type cyclization

Intramolecular Heck cyclization

Intramolecular Heck cyclization reaction

Intramolecular Heck-type cyclization

Intramolecular Keto Ester Cyclizations Synthesis of Cyclanones

Intramolecular Pummerer cyclizations

Intramolecular aldol cyclization

Intramolecular aldol cyclization in -upial synthesis

Intramolecular aldol cyclization in poitediol synthesis

Intramolecular aldol cyclizations

Intramolecular alkylative cyclization

Intramolecular carbenoid-carbonyl cyclization sequence

Intramolecular carbolithiation reactions anionic cyclization

Intramolecular crosslinking cyclization

Intramolecular cyclization construction

Intramolecular cyclization debenzylative

Intramolecular cyclization electrophilic

Intramolecular cyclization modifications

Intramolecular cyclization nickel-catalyzed

Intramolecular cyclization of amino

Intramolecular cyclization polymers

Intramolecular cyclization synthesis

Intramolecular cyclization, of hydroxy

Intramolecular cyclization-elimination

Intramolecular cyclization-elimination enzymatic reaction

Intramolecular cyclization-elimination mechanism

Intramolecular cyclizations Buchwald-Hartwig amination

Intramolecular cyclizations applications

Intramolecular cyclizations chloride

Intramolecular cyclizations heterocycles from

Intramolecular cyclizations of dienes

Intramolecular cyclizations palladium-catalyzed arylation

Intramolecular cyclizations tris silane

Intramolecular cyclizations, palladium bromide

Intramolecular decarboxylative cyclization

Intramolecular double-cyclization

Intramolecular enamine cyclizations

Intramolecular nucleophilic reactions hydroperoxide cyclization

Intramolecular oxidative cyclization

Intramolecular radical cyclizations

Intramolecular radical-induced cyclization

Intramolecular radical-induced stereoselective cyclization

Intramolecular reaction Wittig-Homer cyclization

Intramolecular reaction double cyclization

Intramolecular reaction nitrile oxide cyclization

Intramolecular reaction stereoselective cyclization

Intramolecular reactions Parham cyclizations

Intramolecular reactions cyclization

Intramolecular reactions cyclizations

Intramolecular reactions free radical cyclizations

Intramolecular reactions free-radical cyclization

Intramolecular reductive cyclization

Intramolecular sulfone cyclizations

Intramolecular tandem 1,5-hydride transfer/cyclization process

Lactam synthesis carbonylation, intramolecular cyclization

Lactams intramolecular radical cyclization

Lactone synthesis intramolecular cyclization

Lactone, intramolecular cyclization

Lithium-halogen exchange intramolecular cyclization

McMurry cyclization intramolecular

Michael cyclization intramolecular

Nitrenes intramolecular cyclization

Nitrile oxide cyclization intramolecular

Nitriles intramolecular cyclization, carbonyl

Nucleophile-vinyl cation reaction intramolecular cyclization

Oxetanes intramolecular cyclization reactions

Oxidative addition intramolecular cyclization

Oximes intramolecular cyclization

Phenols intramolecular cyclization

Phenols intramolecular cyclization, carbonyl

Pyrrolidine ring, intramolecular cyclization

Pyrrolidines intramolecular cyclization

Radical cyclization intramolecular

Ruthenium catalysis cyclization, intramolecular

Stereochemical requirements in intramolecular cyclizations

Stereochemistry intramolecular cyclizations

Tandem bimolecular coupling followed by intramolecular cyclization to form a foldable phenylacetylene macrotetracycle

Thermal degradation intramolecular cyclization

Triazine , intramolecular cyclization

Triple bond formation intramolecular cyclization

Wittig-Homer cyclization intramolecular

Wittig-Horner cyclization intramolecular

Zirconocene-Mediated Intramolecular Cyclization of Bis(Alkynyl)Silanes

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