542-92-7

Basic information

• Product Name: 1,3-Cyclopentadiene
• Synonyms: Cyclopentadiene;pentole;pyropentylene;r-pentine;1，3-Cyclopentadiene;2,4-Cyclopentadiene
• CAS NO: 542-92-7
• Molecular Formula: C₅H₆
• Molecular Weight: 66.10114
• EINECS: 208-835-4
• Mol File: 542-92-7.mol
• Article Data: 315

Chemical Properties

• Melting Point: -85°; mp 32.5°
• Boiling Point: bp760 41.5-42.0°
• Appearance: colourless liquid
• Density: d40 0.8235; d410 0.8131; d420 0.8021; d425 0.7966; d430 0.7914
• Vapor Pressure: 418mmHg at 25°C
• Refractive Index: nD16 1.44632
• Solubility: Miscible with acetone, benzene, carbon tetrachloride, and ether. Soluble in acetic acid, aniline, and carbon disulfide (Windholz et al., 1983).
• PKA: 16(at 25℃)
• Water Solubility: 10.3 mM at 25 °C (shake flask-UV spectrophotometry, Streitwieser and Nebenzahl, 1976)
• Stability: Stable at room temperature. Incompatible with oxidizing agents, acids and a wide variety of other compounds. May form peroxides
• CAS DataBase Reference: 1,3-Cyclopentadiene(CAS DataBase Reference)
• NIST Chemistry Reference: 1,3-Cyclopentadiene(542-92-7)
• EPA Substance Registry System: 1,3-Cyclopentadiene(542-92-7)

Safety Data

• RIDADR: 1993
• HazardClass: 3.2
• PackingGroup: III
• Hazardous Substances Data: 542-92-7(Hazardous Substances Data)

Usage

Chemical Properties

Different sources of media describe the Chemical Properties of 542-92-7 differently. You can refer to the following data:
1. colourless liquid
2. Cyclopentadiene is a flammable, colorless liq- uid with a sweet odor, like turpentine.
3. 1,3-Cyclopentadiene is a colorless liquid that dimerizes easily in the presence of peroxides and trichloroacetic acid to a colorless solid.

Physical properties

Colorless liquid with a turpentine-like odor. Odor threshold concentration is 1.9 ppm (quoted, Amoore and Hautala, 1983).

Uses

Different sources of media describe the Uses of 542-92-7 differently. You can refer to the following data:
1. Cyclopentadiene is used in the manufactureof resins, in the synthesis of sesquiterpenesand camphors, and as a ligand in the preparationof metal complexes.
2. manufacture of resins; in organic synthesis as the diene in the Diels-Alder reaction producing sesquiterpenes, synthetic alkaloids, camphors.
3. In manufacture of resins; in organic synthesis

Definition

Different sources of media describe the Definition of 542-92-7 differently. You can refer to the following data:
1. A cyclic hydrocarbon made by cracking petroleum. The molecules have a five-membered ring containing two carbon- carbon double bonds and one CH2 group. It forms the negative cyclopentadienyl ionC5H5-, present in sandwich compounds, such as ferrocene.
2. cyclopentadiene: A colourless liquidcyclic alkene,C5H6; r.d. 0.8021;m.p. –97.2°C; b.p. 40.0°C. It is preparedas a by-product during the fractionaldistillation of crude benzenefrom coal tar. It undergoes condensationreactions with ketones to givehighly coloured compounds (fulvenes)and readily undergoes polymerizationat room temperature togive the dimer, dicyclopentadiene.Cyclopentadiene itself is not an aromaticcompound because it does nothave the required number of pi electrons.However, removal of a hydrogenatom produces the stablecyclopentadienyl ion,C5H5-, whichdoes have aromatic properties. Inparticular, the ring can coordinate topositive ions in such compounds asferrocene.

Production Methods

This compound occurs in the C6–C8 petroleum distillation fraction, and in coke oven light oil fractions. It is produced by dehydrogenation of cyclopentadiene or monomerization of its dimer.

General Description

1，3-Cyclopentadiene is a colorless liquid with an irritating, terpene-like odor. Bp: 42.5°C; Flash point: 77°F. Density: 0.805 g cm-3.

Reactivity Profile

1，3-Cyclopentadiene is incompatible with strong oxidizing agents. Ignites on contact with oxygen (O2) and ozone (O3). Explodes on contact with fuming nitric acid or a mixture of sulfuric acid and nitrogen tetroxide. Reacts vigorously on contact with potassium hydroxide and other strong bases. Mixtures with air are explosive. Presents a moderate explosion hazard when exposed to heat or flame. Decomposes violently at high temperature and pressure. May form explosive peroxides in storage. Undergoes a spontaneous dimerization at room temperature to give DI1，3-Cyclopentadiene (C10H12, CAS No: 77-73-6), which is a low-melting solid (melting point: 32.5°C). The reaction is strongly exothermic (Hazardous Chemicals Desk Reference, p. 360 (1987)), but occurs sufficiently slowly that 1，3-Cyclopentadiene can be said to be stable at room temperature. The dimerization accounts for the partial or complete solidification of liquid 1，3-Cyclopentadiene in storage. Polymerization occurs more rapidly and extensively at higher temperatures. When heated to 180-200°C, 1，3-Cyclopentadiene gives poly1，3-Cyclopentadiene, a white waxy solid. Stronger heating breaks down poly1，3-Cyclopentadiene and re-generates the monomeric 1，3-Cyclopentadiene as a vapor. The vapor decomposes violently at higher temperatures and pressures.

Health Hazard

Cyclopentadiene exhibited low toxicity inanimals. Inhalation produced irritation of theeyes and nose. A 3-mL amount injected subcutaneouslyinto rabbits resulted in narcosis,convulsions, and death (von Oettingen 1940).A dose of≤ 1 mL was nontoxic. Repeatedexposure to 500 ppm caused liver and kidneyinjuries in rats; but longer repeated exposuresto 250 ppm produced no such effects in testanimals (ACGIH 1986). An oral LD50 valuein rats for the dimeric form has been recordedas 820 mg/kg (Smyth 1954).

Fire Hazard

Flammable liquid; flash point (open cup) 32°C (90°F); fire- extinguishing agent: dry chemical, foam, or CO2; a water spray may be used to cool the surroundings. Prolonged exposure to air may cause peroxide formation.

Safety Profile

Low toxicity by ingestion. A dangerous fire hazard when exposed to heat or flame; can react with oxidizing materials. Moderate explosion hazard in the form of gas when exposed to heat or by chemical reaction. It decomposes violently at hgh temperatures and pressures. dimerization is highly exothermic. Explosive reaction with fuming nitric acid,dinitrogen tetroxide, sulfuric acid. Reaction with nitrogen oxide + oxygen forms an explosive product. Reaction with oxygen forms a flame-sensitive explosive product. Ignites on contact with oxygen + ozone. Reacts vigorously on contact with potassium hydroxide. Incompatible with oxides of nitrogen, sulfuric acid. When heated to decomposition it emits acrid smoke and fumes.

Potential Exposure

Cyclopentadiene is used as an inter- mediate in the manufacture of resins, insecticides, fungi- cides, and other chemicals.

Environmental fate

Biological. Cyclopentadiene may be oxidized by microbes to cyclopentanone (Dugan, 1972). Chemical/Physical. Dimerizes to dicyclopentadiene on standing (Windholz et al., 1983).

Shipping

UN1993 Flammable liquids, n.o.s., Hazard Class: 3; Labels: 3-Flammable liquid, Technical Name Required.

Purification Methods

Dry the diene with Mg(ClO4)2 and distil it rapidly as it dimerises readily at room temperature. It should be used immediately or stored in a Dry Ice or an ice-salt bath. HIGHLY FLAMMABLE. [Moffett Org Synth Coll Vol IV 238 1963.] Cyclopentadiene Dimer (4,7-methano-3a,4,7,7a-tetrahydroindene) has [77-73-6], M 132.3, m 33o, b 170o/atm, and d2 5 0.986; add ~0.05% of 2,6-di-tert-butyl-4-methylphenol as stabilizer. Cyclopentadiene is prepared when required by de-polymerising the technical grade dimer by heating it carefully under a fractionating column [Wilkinson Org Synth Coll Vol IV 467 1963], as described by Moffett (above reference), or by adding the dimer at a steady rate onto mineral oil heated at 240-270o (Korach et al. Org Synth 42 50 1962). [Beilstein 5 II 391.]

Incompatibilities

Vapors may form explosive mixture with air. Converted (dimerized) to higher-boiling dicyclopenta- diene upon standing in air and @ 32 F/0 C; this conversion may be violent and exothermic; this reaction is accelerated by peroxides or trichloroacetic acid. Reacts violently with potassium hydroxide. Violent reaction with strong oxidi- zers; strong acids; dinitrogen tetroxide; magnesium. Incompatible with oxidizers (chlorates, nitrates, peroxides, permanganates, perchlorates, chlorine, bromine, fluorine, etc.); contact may cause fires or explosions. Keep away from alkaline materials, strong bases, strong acids, oxoa- cids, epoxides, alkaline earth metals, nitrogen oxides. May accumulate static electrical charges, and may cause ignition of its vapors.

InChI:InChI=1/C5H6/c1-2-4-5-3-1/h1-4H,5H2

Synthetic route

cyclopentene (142-29-0) → cyclopenta-1,3-diene (542-92-7)

Conditions	Yield
With n-butyllithium; potassium 2-methylbutan-2-olate In hexane 1) r.t., 14 h, 2) reflux, 5 h;	100%
at 850℃; Erhitzen unter vermindertem Druck;
With chromium (III)-oxide-aluminium oxide contacts at 450 - 500℃;
With palladium at 180 - 200℃;

trimethylsilylcyclopentadiene (3559-74-8) → cyclopenta-1,3-diene (542-92-7)

Conditions	Yield
With trifluoroacetic acid at 60℃; for 3h; Heating;	100%
With potassium tert-butylate In N,N,N,N,N,N-hexamethylphosphoric triamide at 60℃; for 3h;	100%

manganocene (73138-26-8) + carbon dioxide (124-38-9) + diethylamine (109-89-7) → Mn(O2CN(C2H5)2)2 + cyclopenta-1,3-diene (542-92-7)

Conditions	Yield
In toluene under N2 or Ar;suspn. of Mn(cp)2 in toluene treated with stoicheiometric amt. of amine, clear soln, addn. of CO2, after 2 h no gas was uptaken; evapn.,;	A 99% B n/a

1,3-dihydroxycyclopentane (16326-97-9, 16326-98-0, 59719-74-3) → cyclopenta-1,3-diene (542-92-7)

Conditions	Yield
With Nafion In water at 140℃; Temperature; Solvent; Reagent/catalyst;	99%
With H-USY zeolite In tetrahydrofuran at 249.84℃; Inert atmosphere;	93.8%

(η-cyclopentadienyl)(η-cyclopentadiene)nickel tetrafluoroborate (84651-76-3) + triphenylantimony (603-36-1) → [Ni(C5H5)(Sb(C6H5)3)2](1+)*BF4(1-)=[Ni(C5H5)(Sb(C6H5)3)2]BF4 (85836-36-8) + cyclopenta-1,3-diene (542-92-7)

Conditions	Yield
In diethyl ether under Ar, Ni complex in ether mixed with stibane ligand (molar ratio 1:2), stirred for 5 h at room temp.; filtered, washed with ether, dried in vac., elem. anal.;	A 98% B n/a

vanadocene + lead(IV) tetraacetate (546-67-8) → {(η5-cyclopentadienyl)vanadium diacetate}2 + lead acetate (301-04-2) + cyclopenta-1,3-diene (542-92-7)

Conditions	Yield
In toluene molar ratio Cp2V/Pb-compound 1/1, sealed ampoule, 20°C, 48 h;	A 97% B n/a C 36.6%

dicyclopentadiene (77-73-6, 933-60-8, 1755-01-7, 13257-74-4, 25850-35-5, 57429-84-2, 109428-68-4) → cyclopenta-1,3-diene (542-92-7)

Conditions	Yield
Heating;	96%
at 180℃;
In decalin at 180℃; Diels-Alder Cycloaddition; Inert atmosphere;

bi(cyclopentadiene) (77-73-6, 933-60-8, 1755-01-7) → cyclopenta-1,3-diene (542-92-7)

Conditions	Yield
at 160℃;	95%
at 350 - 400℃;	91%
at 210℃;	84.5%

endo-4a-acetyl-2,3-dichloro-4a,5,8,8a-tetrahydro-5,8-methano-1,4-naphthoquinone (79756-02-8, 79813-47-1) → cyclopenta-1,3-diene (542-92-7) + 4-acetyl-6,7,7',8'-tetrachloro-3'aR*,9'bR*-dihydro-5,6',9'-trihydroxy-spiro<3H-benzofuran-2S*,5'(1'H)-cyclopenta<2>benzopyran> (79756-04-0)

Conditions	Yield
In benzene-d6 at 80℃; for 6h; sealed n.m.r. sample tube;	A n/a B 95%

bicyclo[4.3.0]nona-3,7-diene (3048-65-5) + dicyclopentadiene (77-73-6, 933-60-8, 1755-01-7, 13257-74-4, 25850-35-5, 57429-84-2, 109428-68-4) → cyclopenta-1,3-diene (542-92-7)

Conditions	Yield
With tert-butylhydroquinone In diphenylether at 215℃; for 2.58333h; Product distribution / selectivity;	94.19%

vanadocene + dibutyltin dibenzoate (5847-54-1) → tin (7440-31-5) + 2C5H5(1-)*2V(3+)*4OCOC6H5(1-) = [(C5H5)V(OCOC6H5)2]2 + (Benzoyloxy)tributylstannan (4342-36-3) + dibutyltin (1191-48-6) + cyclopenta-1,3-diene (542-92-7)

Conditions	Yield
In toluene molar ratio Cp2V/Sn-compound 1/2, sealed ampoule, 20°C, 24 h;	A n/a B 94% C n/a D n/a E 84%

(η-cyclopentadienyl)(η-cyclopentadiene)nickel tetrafluoroborate (84651-76-3) + 1-diphenylarsino-2-diphenylphosphinoethane (23582-06-1) → cyclopentadienylnickel(diphenylphosphino(diphenylarsino)ethylidene) (85412-97-1) + cyclopenta-1,3-diene (542-92-7)

Conditions	Yield
In chloroform under Ar, Ni complex and ligand stirred in CHCl3 for 5 min; filtered, filtrate dropped in ether, filtered, dried in vac., elem. anal.;	A 93% B n/a

(S)-2-(2-Aza-bicyclo[2.2.1]hept-5-en-2-yl)-3-phenyl-propionic acid methyl ester (211567-40-7) → N-methyl-L-phenylalanine methyl ester (2439-60-3, 27442-39-3) + cyclopenta-1,3-diene (542-92-7)

Conditions	Yield
With triethylsilane; trifluoroacetic acid In chloroform for 20h; Ambient temperature;	A 92% B n/a

(1R,4S,4aR,8aS)-1,4,5,6,7,8-Hexahydro-1,4-methano-naphthalene-4a,8a-dicarboxylic acid dimethyl ester → 1,2-dimethyl cyclohex-1-ene-1,2-dicarboxylate (4336-19-0) + cyclopenta-1,3-diene (542-92-7)

Conditions	Yield
In gas at 650℃;	A 92% B n/a

(η-cyclopentadienyl)(η-cyclopentadiene)nickel tetrafluoroborate (84651-76-3) + 2,4-dichloro-1,3-di-tert-butyl-1,3,2,4-diazadiphosphetidine (24335-35-1) → [(C5H5)Ni(P2Cl2(NC(CH3)3)2)2](1+)*BF4(1-)=[(C5H5)Ni(P2Cl2(NC(CH3)3)2)2]BF4 (85413-22-5) + cyclopenta-1,3-diene (542-92-7)

Conditions	Yield
In chloroform under Ar, nickel complex and CHCl3 soln. of ligand (molar ratio 1:2) stirred at 0°C for 1 h; filtered, filtrate mixed with ether, decanted, washed with ether until solidification, dried in vac., elem. anal.;	A 92% B n/a

Tricyclo<5.2.1.02.6>deca-3,8-dien (247936-95-4) → cyclopenta-1,3-diene (542-92-7)

Conditions	Yield
at 0 - 20℃; under 50 - 100 Torr; Temperature; Inert atmosphere; Large scale;	91.7%
at 158.5 - 220.7℃; Kinetics; Rate constant; Thermodynamic data; activation parameters: Ea, ΔH, ΔS;
at 160 - 170℃;

C16H20O4 (132785-65-0) → 2,2-Dimethyl-cyclopenta-3,5-diene-1,3-dicarboxylic acid dimethyl ester (132785-67-2) + cyclopenta-1,3-diene (542-92-7)

Conditions	Yield
In neat (no solvent) at 160℃;	A n/a B 91%
In neat (no solvent) at 160℃;	A 91% B n/a

1-((1S,3R,7R)-4,4-Dioxo-4λ6-thia-tricyclo[5.2.1.02,6]dec-8-en-3-yl)-pentan-1-one (93469-35-3) → cyclopenta-1,3-diene (542-92-7) + trans-1,3-nonadien-5-one (83339-20-2)

Conditions	Yield
at 650℃; under 0.01 Torr;	A n/a B 91%

(S)-2-(2-Aza-bicyclo[2.2.1]hept-5-en-2-yl)-4-methyl-pentanoic acid methyl ester (112018-28-7, 112018-29-8, 126574-84-3) + trifluoroacetic acid (76-05-1) → cyclopenta-1,3-diene (542-92-7) + dimethylleucine trifluoroacetate (111934-20-4)

Conditions	Yield
With triethylsilane In chloroform for 20h; Ambient temperature;	A n/a B 91%

8-quinolinol (148-24-3) + tris(cyclopentadienyl)ytterbium(III) → dicyclopentadienylytterbium 8-quinolinolate + cyclopenta-1,3-diene (542-92-7)

Conditions	Yield
In tetrahydrofuran Addn. of Yb-complex soln to soln. of 8-hydroxyquinoline under Ar, stirring 24 h at room temp.; Concg., addn. of n-hexane pptd. a solid, washing (n-hexane), crystn. (THF/n-hexane), elem. anal.;	A 91% B n/a

(1S,3S,7R)-3-Pentyl-4-thia-tricyclo[5.2.1.02,6]dec-8-ene 4,4-dioxide (83927-51-9) → (E)-1,3-nonadiene (77192-27-9) + cyclopenta-1,3-diene (542-92-7)

Conditions	Yield
at 650℃; under 0.01 Torr;	A 90% B n/a
at 650℃; Yields of byproduct given;

2-(5-Norbornen-2-yl)imidazol (91937-77-8) → 2-vinyl imidazole (43129-93-7) + cyclopenta-1,3-diene (542-92-7)

Conditions	Yield
With 4-methoxy-phenol In methanol at 500℃;	A 90% B n/a

((1S,3R,7R)-4,4-Dioxo-4λ6-thia-tricyclo[5.2.1.02,6]dec-8-en-3-yl)-trimethyl-silane (86593-81-9) → (E)-1-(trimethylsilyl)buta-1,3-diene (71504-26-2) + cyclopenta-1,3-diene (542-92-7)

Conditions	Yield
at 650℃; under 0.01 Torr;	A 89% B n/a

vanadocene + tributyltin acetate (56-36-0) → {(η5-cyclopentadienyl)vanadium diacetate}2 + bis(tri-n-butyltin) (813-19-4) + cyclopenta-1,3-diene (542-92-7)

Conditions	Yield
In neat (no solvent) molar ratio Cp2V/Sn-compound 1/2, sealed ampoule, 120°C, 16 h; elem. anal.;	A 89% B 10.07% C 58.5%

(S)-(2-Aza-bicyclo[2.2.1]hept-5-en-2-yl)-phenyl-acetic acid methyl ester (111934-15-7, 112018-33-4, 112458-30-7, 112458-34-1) → cyclopenta-1,3-diene (542-92-7) + methyl (2S)-(methylamino)(phenyl)acetate (111934-22-6)

Conditions	Yield
With triethylsilane; trifluoroacetic acid In chloroform for 20h; Ambient temperature;	A n/a B 88%

3-benzoyl-2-oxa-3-azabicyclo<2.2.1>hept-5-ene (59438-62-9) + benzylamine (100-46-9) → N-benzylbenzamide (1485-70-7) + cyclopenta-1,3-diene (542-92-7)

Conditions	Yield
In toluene at 80℃; for 20h; Product distribution; Mechanism; var. amine; determination of formed N2O; retro-Diels Alder dissociation;	A 88% B n/a

(η-cyclopentadienyl)(η-cyclopentadiene)nickel tetrafluoroborate (84651-76-3) + trimethylantimony (594-10-5) → [Ni(C5H5)(Sb(CH3)3)2](1+)*BF4(1-)=[Ni(C5H5)(Sb(CH3)3)2]BF4 (85836-32-4) + cyclopenta-1,3-diene (542-92-7)

Conditions	Yield
In diethyl ether under Ar, Ni complex in ether mixed with stibane ligand (molar ratio 1:2), stirred for 5 h at room temp.; filtered, washed with ether, dried in vac., elem. anal.;	A 88% B n/a

tris(cyclopentadienyl)ytterbium(III) + 2-amino-phenol (95-55-6) → dicyclopentadienylytterbium o-aminophenolate + cyclopenta-1,3-diene (542-92-7)

Conditions	Yield
In tetrahydrofuran Addn. of Yb-complex soln to soln. of o-aminophenol under Ar, stirring 24 h at room temp.; Concg., addn. of n-hexane pptd. a solid, washing (n-hexane), crystn. (THF/n-hexane), elem. anal.;	A 87% B n/a

8-quinolinol (148-24-3) + tris(cyclopentadienyl)neodymium(III) (1080547-39-2) → dicyclopentadienylneodymium 8-quinolinolate + cyclopenta-1,3-diene (542-92-7)

Conditions	Yield
In tetrahydrofuran Addn. of Nd-complex soln to soln. of 8-hydroxyquinoline under Ar, stirring 24 h at room temp.; Concg., addn. of n-hexane pptd. a solid, washing (n-hexane), crystn. (THF/n-hexane), elem. anal.;	A 87% B n/a

[Ni(C5H5)(Sb(C6H5)3)2](1+)*BF4(1-)=[Ni(C5H5)(Sb(C6H5)3)2]BF4 (85836-36-8) + bis(diphenylstibino)methane (30224-53-4) → [Ni(C5H5)(Sb(C6H5)2CH2Sb(C6H5)2)2](1+)*BF4(1-)=[Ni(C5H5)(Sb(C6H5)2CH2Sb(C6H5)2)2]BF4 (85836-38-0) + cyclopenta-1,3-diene (542-92-7)

Conditions	Yield
In chloroform under Ar, Ni complex in CHCl3 mixed at 0°C with stibane ligand (molar ratio 1:2), stirred for 10 min; filtered, to filtrate added ether, solid washed with ether, dried in vac., elem. anal.;	A 87% B n/a

cyclohexanone (108-94-1) + cyclopenta-1,3-diene (542-92-7) → cyclopenta-2,4-dien-1-ylidenecyclohexane (3141-04-6)

Conditions	Yield
Stage #1: cyclohexanone; cyclopenta-1,3-diene With pyrrolidine In methanol at 20℃; Inert atmosphere; Stage #2: With acetic acid In methanol for 0.15h;	100%
In methanol for 0.416667h; Ambient temperature; new method;	96%
With pyrrolidine In methanol for 0.416667h; Ambient temperature;	96%

fumaryl dichloride (627-63-4) + cyclopenta-1,3-diene (542-92-7) → endo,exo-bicyclo[2.2.1]hept-2-ene-5,6-dicarboxylic acid dichloride (4582-21-2)

Conditions	Yield
In toluene Heating;	100%
With diethyl ether
In diethyl ether

cyclopenta-1,3-diene (542-92-7) + acrylic acid methyl ester (292638-85-8) → (1S,2S,4S)-Bicyclo[2.2.1]hept-5-ene-2-carboxylic acid methyl ester (2903-75-5)

Conditions	Yield
In water Ambient temperature;	100%
With 3-phenyl-propenal; bromocatecholborane In dichloromethane at -78℃; for 3h;	98%
With [BCl2(1-methylimidazole)][Al2Cl7] In neat (no solvent) at 0℃; for 0.0833333h; Diels-Alder Cycloaddition; Inert atmosphere;	93%

cyclopenta-1,3-diene (542-92-7) + (2E)-but-2-enedioic acid (110-17-8) → norbornene-5,6-dicarboxylic acid (1200-88-0)

Conditions	Yield
In water; acetone at 50℃; for 24h; Diels-Alder Cycloaddition;	100%
In 1,4-dioxane at 60℃; for 1h;	94%
With N,N-dimethyl-formamide andere polare Loesungsmittel;

cyclopenta-1,3-diene (542-92-7) + acetone (67-64-1) → 6,6'-dimethyl fulvene (2175-91-9)

Conditions	Yield
Stage #1: cyclopenta-1,3-diene; acetone With pyrrolidine In methanol at 20℃; Inert atmosphere; Stage #2: With acetic acid In methanol for 0.15h;	100%
With pyrrolidine In methanol at -10 - 20℃; for 1h; Inert atmosphere;	100%
With methylamine for 4.5h;	92%

cyclopenta-1,3-diene (542-92-7) + p-benzoquinone (106-51-4) → norbornenoquinone (51175-59-8)

Conditions	Yield
In hexane; ethyl acetate at 0℃; for 3.5h; Diels-Alder Cycloaddition;	100%
In methanol at -78 - 0℃; Inert atmosphere; optical yield given as %de;	98%
In hexane; ethyl acetate at 0℃; for 4h; Diels-Alder reaction;	97%

cyclopenta-1,3-diene (542-92-7) + Acetylenedicarboxylic acid (142-45-0) → bicyclo[2.2.1]hepta-2,5-diene-2,3-dicarboxylic acid (15872-28-3)

Conditions	Yield
In 1,4-dioxane at 20℃; for 12h; Diels-Alder cycloaddition;	100%
In diethyl ether Ambient temperature;	85%
Stage #1: Acetylenedicarboxylic acid With (2-bromophenyl)boronic acid In dichloromethane at 25℃; for 0.166667h; Inert atmosphere; Stage #2: cyclopenta-1,3-diene In dichloromethane at 25℃; for 48h; Diels-Alder cycloaddition; Inert atmosphere;	84%

cyclopenta-1,3-diene (542-92-7) + diethylazodicarboxylate (1972-28-7) → diethyl 2,3-diazanorbornene-2,3-dicarboxylate (14011-60-0)

Conditions	Yield
In dichloromethane at 0℃;	100%
In diethyl ether at 0℃; for 12h;	100%
In diethyl ether; toluene at 20℃; for 21.5h; Reflux;	55%
With diethyl ether

cyclopenta-1,3-diene (542-92-7) + 1,2-Dicyanoethylene (764-42-1) → bicyclo<2.2.1>hept-5,6-ene-2α,3β-dicarbonitrile (6343-16-4, 24425-58-9, 38447-89-1, 51252-31-4)

Conditions	Yield
In methanol at 0 - 20℃; Diels-Alder reaction;	100%
In methanol at 0℃; for 1h; Diels-Alder Cycloaddition;	99%
In 1,4-dioxane for 6h; Ambient temperature;	93%

cyclopenta-1,3-diene (542-92-7) → endo-Dicyclopentadien (1755-01-7)

Conditions	Yield
In cyclohexane at 119.84℃; for 2h; Diels-Alder Cycloaddition;	100%

cyclopenta-1,3-diene (542-92-7) + acrolein (107-02-8) → (+/-)-endo-bicyclo[2.2.1]hept-5-ene-2-carbaldehyde (19926-90-0)

Conditions	Yield
With trityl tetrafluoroborate In dichloromethane at 20℃; for 16h; Diels-Alder Cycloaddition;	100%
With methyltrioxorhenium(VII) In chloroform for 1h; Ambient temperature;	90%
With 1-ethyl-3-methyl-1H-imidazol-3-ium chloride at 20℃; for 0.166667h; Diels-Alder reaction;	88%

maleic anhydride (108-31-6) + cyclopenta-1,3-diene (542-92-7) → 3,6-endomethylene-1,2,3,6-tetrahydrophthalic anhydride (129-64-6)

Conditions	Yield
With 3-(n-butoxycarbonyl)-1-methylpyridinium bis(trifluoromethanesulfonyl)imide at 20℃; for 0.166667h; Diels-Alder reaction; diastereoselective reaction;	100%
With 1-hexyl-3-methylimidazolium tetrafluoroborate; K-10 montmorillonite at 20℃; for 0.0833333h; Diels-Alder reaction;	99%
In dichloromethane at 0 - 20℃; for 10h; Diels-Alder Cycloaddition; Inert atmosphere;	98%

N-phenyl-maleimide (941-69-5) + cyclopenta-1,3-diene (542-92-7) → N-phenylbicyclo[2.2.1]hept-5-ene-2-endo,3-endo-dicarboximide (26234-46-8, 29377-36-4, 56552-68-2)

Conditions	Yield
In neat (no solvent) at 20℃; for 0.0166667h; Diels-Alder Cycloaddition;	100%
With 1-hexyl-3-methylimidazolium tetrafluoroborate; K-10 montmorillonite at 20℃; for 0.0833333h; Diels-Alder reaction;	99%
With 3-(n-butoxycarbonyl)-1-methylpyridinium bis(trifluoromethanesulfonyl)imide at 20℃; for 0.166667h; Diels-Alder reaction; diastereoselective reaction;	97%

1,3-diacetyl-2,3-dihydro-1H-imidazol-2-one (20212-13-9) + cyclopenta-1,3-diene (542-92-7) → (3aα,4α,7α,7aα)-1,3-diacetyl-1,3,3a,4,7,7a-hexahydro-4,7-methano-2H-benzimidazol-2-one (78932-02-2)

Conditions	Yield
at 140℃; for 24h; Diels-Alder reaction;	100%
at 140℃; for 24h; Diels-Alder Cycloaddition; Sealed tube;	98.6%
In xylene at 180℃; selaed tube;	69%

formaldehyd (50-00-0) + benzylamine hydrochloride (3287-99-8, 39110-74-2) + cyclopenta-1,3-diene (542-92-7) → N-benzyl-2-azanorborn-5-ene (112375-05-0)

Conditions	Yield
In water	100%
In water at 20℃; for 3h;	73%
In water for 3h; Ambient temperature; Yield given;
In water for 16h; Ambient temperature;	6.69 g
In water at 20℃; for 3h;

1-(chloromethyl)maleic anhydride (41702-49-2) + cyclopenta-1,3-diene (542-92-7) → (1S,2S,6S,7R)-2-Chloromethyl-4-oxa-tricyclo[5.2.1.02,6]dec-8-ene-3,5-dione (143668-21-7)

Conditions	Yield
In diethyl ether 1) 0.5 h, reflux, 2) RT, 3 h;	100%

2,3-Dimethoxy-5-methyl-1,4-benzoquinone (605-94-7) + cyclopenta-1,3-diene (542-92-7) → 4,5-dimethoxy-2-methyltricyclo<6.2.1.02,7>undeca-4,9-diene-3,6-dione

Conditions	Yield
In dichloromethane for 96h; Ambient temperature;	100%

4-oxopent-2-ynoic acid methyl ester (41726-06-1) + cyclopenta-1,3-diene (542-92-7) → 3-Acetyl-bicyclo[2.2.1]hepta-2,5-diene-2-carboxylic acid methyl ester (148042-65-3)

Conditions	Yield
In dichloromethane for 18h;	100%

trifluoromethyldiiodophosphine (421-59-0) + cyclopenta-1,3-diene (542-92-7) → 2,3-Bis-trifluoromethyl-2,3-diphospha-bicyclo[2.2.1]hept-5-ene (104927-58-4)

Conditions	Yield
With tin(ll) chloride In tetrahydrofuran	100%

1,1-bis(trichlorosilyl)ethylene (684-18-4) + cyclopenta-1,3-diene (542-92-7) → 5,5-Bis-trichlorosilanyl-bicyclo[2.2.1]hept-2-ene (120852-93-9)

Conditions	Yield
at 60 - 70℃; for 3h;	100%

5-hydroxynaphtho-1,4-quinone (481-39-0) + cyclopenta-1,3-diene (542-92-7) → (1R*,4S*,4aR*,9aS*)-1,4,4a,9a-tetrahydro-5-hydroxy-1,4-methano-9,10-anthracenedione (163180-66-3)

Conditions	Yield
In chloroform for 0.5h; Ambient temperature;	100%
In propan-1-ol at 25℃; Thermodynamic data; Rate constant; other solvents and their mixture with water; isobaric activation parameters;
In dichloromethane at 20℃; Reflux;

di-tert-butyl-diazodicarboxylate (870-50-8) + cyclopenta-1,3-diene (542-92-7) → di-tert-butyl 2,3-diazabicyclo[2.2.1]hept-5-ene-2,3-dicarboxylate (39203-22-0)

Conditions	Yield
In dichloromethane at 0℃;	100%
In diethyl ether for 48h; Ambient temperature;	94%
In dichloromethane Inert atmosphere;	89%
In dichloromethane	89%
In diethyl ether at 0℃; for 12h;

styrylphosphonic acid (1707-08-0) + cyclopenta-1,3-diene (542-92-7) → (3-phenylbicyclo<2.2.1>hept-5-en-2-yl)phosphonic acid

Conditions	Yield
In diethyl ether for 72h; Ambient temperature;	100%
In diethyl ether at 20℃; for 48h;	91.5%

2-benzylcyclohexa-2,5-diene-1,4-dione (38940-10-2) + cyclopenta-1,3-diene (542-92-7) → rel-(1S,4R,4aS,8aR)-6-benzyl-1,4,4a,8a-tetrahydro-1,4-methanonaphthalene-5,8-dione (100848-86-0, 117893-87-5)

Conditions	Yield
for 0.416667h; Ambient temperature;	100%
In methanol at 25℃; Diels-Alder reaction;	82%

2,3-dichloro-1,4-benzoquinone (5145-42-6) + cyclopenta-1,3-diene (542-92-7) → 4,5-dichlorotricyclo<6.2.1.02,7>undeca-4,9-diene-3,6-dione (82253-62-1)

Conditions	Yield
In diethyl ether at 20℃; for 5h; Diels-Alder reaction;	100%
In benzene Yield given;
In benzene Diels-Alder Cycloaddition;

1,2-dichloro-1,2-dicyanoethylene (85278-93-9) + cyclopenta-1,3-diene (542-92-7) → 2,3-Dichloro-bicyclo[2.2.1]hept-5-ene-2,3-dicarbonitrile (86165-09-5)

Conditions	Yield
In dichloromethane at 25℃; for 72h;	100%

2,3-Dichloro-5-methyl-2,5-cyclohexadiene-1,4-dione (30685-19-9) + cyclopenta-1,3-diene (542-92-7) → (1α,4α,4aβ,8aβ)-6,7-Dichloro-1,4,4a,8a-tetrahydro-4a-methyl-1,4-methanonaphthalene-5,8-dione

Conditions	Yield
In methanol for 2h;	100%

Oxo-(4-phenylazo-phenylamino)-dithioacetic acid methyl ester (104688-95-1) + cyclopenta-1,3-diene (542-92-7) → (1R,4S)-3-Methylsulfanyl-2-thia-bicyclo[2.2.1]hept-5-ene-3-carboxylic acid (4-phenylazo-phenyl)-amide (110968-47-3)

Conditions	Yield
In chloroform Heating;	100%

Upstream product

• 5452-28-8 7,7-diphenylbicyclo<3.2.0>hept-2-en-6-one 
• 51175-59-8 norbornenoquinone 
• 71-43-2 benzene 
• 186581-53-3 diazomethane 
• 107750-71-0 5,8-dimethoxy-1,4-dihydro-1,4-methanoanthracene-9,10-dione 
• 67-56-1 methanol 
• 84927-17-3 C₆H₉N₃O₂ 
• 6746-94-7 Cyclopropylacetylene 
• 4505-48-0 2-phenylindene 
• 116775-54-3 C₂₉H₃₀O 
• 947-57-9 dimethyl bicyclo[2.2.1]hept-2,5-diene-2,3-dicarboxylate 
• 231289-36-4 C,N-Diphenylnitrilimine 
• 2999-78-2 1,1-dichloro-1-silacyclohexa-2,4-diene 
• 504-60-9 penta-1,3-diene 

Downstream Products

• 120-74-1 endo-norbornenecarboxylic acid 
• 28871-71-8 (+/-)-2-methyl-norborn-5-ene-2exo,3exo-dicarboxylic acid 
• 826-62-0 5-norbornene-2,3-dicarboxylic anhydride 
• 21181-95-3 4-norborn-5-en-2-yl-pyridine 
• 54454-26-1 6-exo, 7-endo-Diphenylbicyclo<3.2.0>hept-2-en 
• 22094-85-5 5-decyl-2-norbornene 
• 72602-64-3 bicyclo[2.2.1]hepta-2,5-diene-2,3-dicarbaldehyde 
• 2843-35-8 1,2-Dichlorethylen-cyclopentadien-Addukt 
• 24430-29-3 Spiro<4.4>nona-1,3,7-trien 
• 53624-84-3 3-methyl-bicyclo<2,2,1>-5-hepten-2-carboxylic acid 
• 173006-06-9 1-((1R,2R,3S,4S)-3-Acetyl-bicyclo[2.2.1]hept-5-en-2-yl)-ethanone 
• 5602-35-7 1,4-Endomethylen-cyclohex-5-en-trans-2,3-dicarbonsaeurediamid 
• 22094-83-3 5-hexyl-2-norbornene 
• 5257-46-5 (bicyclo<2.2.1>heptene-5 yle-2)-1 propanone-1, endo 

Relevant articles and documents

Photoinduced Isomerization of Radical Ions. 3. Radical Cations of Cyclopentadiene, Dicyclopentadienes, and 1,3-Bishomocubane Produced in γ-Irradiated Freon Matrices

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This contribution describes the design and synthesis of multifunctional micelles based on amphiphilic brush block copolymers (BBCPs) for imaging and selective drug delivery of natural anticancer compounds. Well-defined BBCPs were synthesized via one-pot multi-step sequential grafting-through ring-opening metathesis polymerization (ROMP) of norbornene-based macroinitiators. The norbornenes employed contain a poly(ethylene glycol) methyl ether chain, an alkyl bromide chain, and/or a near-infrared (NIR) fluorescent cyanine dye. After block copolymerization, post-polymerization transformations using bromide-azide substitution, followed by the strain-promoted azide-alkyne cycloaddition (SPAAC) allowed for the functionalization of the BBCPs with the piplartine (PPT) moiety, a natural product with well-documented cytotoxicity against cancer cell lines, via an ester linker between the drug and the polymer side chain. The amphiphilic BBCPs self-assembled in aqueous media into nano-sized spherical micelles with neutral surface charges, as confirmed by dynamic light scattering analysis and transmission electron microscopy. During self-assembly, paclitaxel (PTX) could be effectively encapsulated into the hydrophobic core to form stable PTX-loaded micelles with high loading capacities and encapsulation efficiencies. The NIR fluorescent dye-containing micelles exhibited remarkable photophysical properties, excellent colloidal stability under physiological conditions, and a pH-induced disassembly under slightly acidic conditions, allowing for the release of the drug in a controlled manner. The in vitro studies demonstrated that the micelles without the drug (blank micelles) are biocompatible at concentrations of up to 1 mg mL-1 and present a high cellular internalization capacity toward MCF-7 cancer cells. The drug-functionalized micelles showed in vitro cytotoxicity comparable to free PPT and PTX against MCF-7 and PC3 cancer cells, confirming efficient drug release into the tumor environment upon cellular internalization. Furthermore, the drug-functionalized micelles exhibited higher selectivity than the pristine drugs and preferential cellular uptake in human cancer cell lines (MCF-7 and PC3) when compared to the normal breast cell line (MCF10A). This study provides an efficient strategy for the development of versatile polymeric nanosystems for drug delivery and image-guided diagnostics. Notably, the easy functionalization of BBCP side chains via SPAAC opens up the possibility for the preparation of a library of multifunctional systems containing other drugs or functionalities, such as target groups for recognition.