504-31-4

Basic information

• Product Name: ALPHA-PYRONE
• Synonyms: chloro-4’phenyl-4methyl-6phenyl-3tetrahdyro-3,4,5,6pyrone-6(3r*,4s*,6r*;Coumalin;pyran-2-one;tetrahydro-4-(4-chlorophenyl)-6-methyl-3-phenyl-,(3-alpha,4-beta,6-alpha)-2h-pyran-2-on;α-Pyron;2H-PYRAN-2-ONE;ALPHA-PYRONE;Pyrone,alpha-
• CAS NO: 504-31-4
• Molecular Formula: C₅H₄O₂
• Molecular Weight: 96.08
• EINECS: 207-990-5
• Product Categories: Building Blocks;Chemical Synthesis;Heterocyclic Building Blocks;Pyrans
• Mol File: 504-31-4.mol
• Article Data: 17

Chemical Properties

• Melting Point: 8-9 °C
• Boiling Point: 102-103 °C20 mm Hg(lit.)
• Flash Point: 94 °C
• Appearance: Clear yellow to brown/Liquid
• Density: 1.197 g/mL at 25 °C(lit.)
• Vapor Pressure: 0.225mmHg at 25°C
• Refractive Index: n20/D 1.53(lit.)
• Storage Temp.: Refrigerator (+4°C)
• BRN: 1511
• CAS DataBase Reference: ALPHA-PYRONE(CAS DataBase Reference)
• NIST Chemistry Reference: ALPHA-PYRONE(504-31-4)
• EPA Substance Registry System: ALPHA-PYRONE(504-31-4)

Safety Data

• Safety Statements: 23-24/25
• WGK Germany: 3
• F: 8-9-23
• Hazardous Substances Data: 504-31-4(Hazardous Substances Data)

Usage

Chemical Properties

clear yellow to brown liquid

Synthesis Reference(s)

Journal of the American Chemical Society, 90, p. 2318, 1968 DOI: 10.1021/ja01011a020Organic Syntheses, Coll. Vol. 6, p. 462, 1988

General Description

2H-Pyran-2-one (a-Pyrone) is a heterocyclic building block. Photochemistry of 2H-pyran-2-one has been investigated by laser flash photolysis with infrared detection. Ketene and a bicyclic lactone were obtained as major photoproducts.

Purification Methods

Dissolve -pyrone in Et2O, wash it with brine, dry (Na2SO4), f

InChI:InChI=1/C5H4O2/c6-5-3-1-2-4-7-5/h1-4H

Synthetic route

5-bromo-5,6-dihydro-2H-pyran-2-one (53646-72-3) → pyran-2-one (504-31-4)

Conditions	Yield
With triethylamine In toluene at 5 - 40℃;	89%
With triethylamine for 0.5h; Dehydrobromination; Heating;	70%
With triethylamine Yield given;

hexane-3,4-cis-diol-2,5-dione (25566-16-9) → pyran-2-one (504-31-4)

Conditions	Yield
With sodium dihydrogenphosphate; sodium hydroxide In acetic acid butyl ester; water at 80℃; for 12h;	79.7%

3-bromo-2H-pyran-2-one (19978-32-6) + lithium dimethylcuprate (15681-48-8) → 3-methyl-2H-pyran-2-one (31678-73-6) + pyran-2-one (504-31-4)

Conditions	Yield
In diethyl ether at -78℃; for 2h; Yields of byproduct given;	A 5% B n/a

2-oxo-2H-pyran-6-carboxylic acid (672-67-3) → pyran-2-one (504-31-4)

Conditions	Yield
With copper

2H-pyran-2-one-5-carboxylic acid (500-05-0) → pyran-2-one (504-31-4)

Conditions	Yield
With copper at 650℃; under 5 Torr;

5-diazo-1,3-cyclopentadiene (1192-27-4) → pyran-2-one (504-31-4) + cyclopentadienone (13177-38-3) + cyclopentadienylidene (4729-01-5) + (Z)-5-Oxo-penta-2,4-dienal (39763-18-3) + Dioxirane

Conditions	Yield
With oxygen at -253.2℃; Mechanism; Irradiation; other temperatures, different λ, reaction with (18)O(16)O and (18)O2;

5-diazo-1,3-cyclopentadiene (1192-27-4) → pyran-2-one (504-31-4) + cyclopentadienone (13177-38-3) + (Z)-5-Oxo-penta-2,4-dienal (39763-18-3)

Conditions	Yield
With oxygen In solid matrix at -253.2℃; Product distribution; Mechanism; Irradiation; further with <18O>O2;

tricyclo<23,6.1.1.0>pyran-2-one (19192-82-6) → pyran-2-one (504-31-4) + 1,3-cyclobutadiene (1120-53-2)

Conditions	Yield
at 620℃;

exo-4,5-epoxy-exo-10-oxatricyclo<5.2.1.02,6>deca-8-en-3-one (69528-36-5, 127642-28-8) → pyran-2-one (504-31-4) + 4,5-epoxy-2-cyclopentenone (68781-88-4, 129076-58-0)

Conditions	Yield
under 0.04 Torr; for 1.5h; flash vacuum thermolysis; T1 75 deg C / T2 375 deg C; Yield given;

cyclopentadienone O-oxide (88766-67-0) → pyran-2-one (504-31-4) + cyclopentadienone (13177-38-3) + (Z)-5-Oxo-penta-2,4-dienal (39763-18-3) + cyclopentadienone oxide (68781-88-4)

Conditions	Yield
Mechanism; Irradiation;

mercuro salt of/the/ coumalic acid → pyran-2-one (504-31-4)

Conditions	Yield
Beim Destillieren im Wasserstoffstrom;

3-oxabicyclo<3.2.0>hept-6-ene-2,4-dione (10374-07-9) → 2-oxa-3-oxobicyclo[2.2.0]hex-5-ene (22980-23-0) + pyran-2-one (504-31-4) + 1,3-cyclobutadiene (1120-53-2) + (Z)-5-Oxo-penta-2,4-dienal (39763-18-3) + CO, CO2

Conditions	Yield
In solid matrix at -269.2 - -248.2℃; Product distribution; Mechanism; Irradiation; irradiation with 248 nm, subsequent bleaching with 254- and 313 nm light destroys part of products; also with isotopomers;

3-oxabicyclo<3.2.0>hept-6-ene-2,4-dione (10374-07-9) → 3-buten-1-yne (689-97-4) + pyran-2-one (504-31-4) + cyclopentadienone (13177-38-3) + CO2

Conditions	Yield
at 850℃; Product distribution; detection on argon matrix, 10 K;

6-methoxy-2H-pyran-3(6H)-one (60249-17-4) → pyran-2-one (504-31-4)

Conditions	Yield
Multi-step reaction with 4 steps 1: 90 percent / LiAlH4 / diethyl ether / 0.5 h / -60 °C 2: 72 percent / NBS; Me2S / CH2Cl2 / 1 h / 0 °C 3: 90 percent / Jones reagent / acetone / 0.5 h 4: 70 percent / Et3N / 0.5 h / Heating View Scheme

6-hydroxy-3,6-dihydro-2H-pyran-3-one (35436-57-8) → pyran-2-one (504-31-4)

Conditions	Yield
Multi-step reaction with 5 steps 1: 75 percent / Ag2O / acetone / 24 h / 20 °C 2: 90 percent / LiAlH4 / diethyl ether / 0.5 h / -60 °C 3: 72 percent / NBS; Me2S / CH2Cl2 / 1 h / 0 °C 4: 90 percent / Jones reagent / acetone / 0.5 h 5: 70 percent / Et3N / 0.5 h / Heating View Scheme

methyl 2,3-dideoxy-α,β-DL-glycero-pent-2-enopyranoside (283156-05-8) → pyran-2-one (504-31-4)

Conditions	Yield
Multi-step reaction with 3 steps 1: 72 percent / NBS; Me2S / CH2Cl2 / 1 h / 0 °C 2: 90 percent / Jones reagent / acetone / 0.5 h 3: 70 percent / Et3N / 0.5 h / Heating View Scheme

3-bromo-6-methoxy-3,6-dihydro-2H-pyran (283156-10-5) → pyran-2-one (504-31-4)

Conditions	Yield
Multi-step reaction with 2 steps 1: 90 percent / Jones reagent / acetone / 0.5 h 2: 70 percent / Et3N / 0.5 h / Heating View Scheme

exo-10-oxatricyclo<5.2.1.02,6>deca-4,8-dien-3-one (64919-86-4, 69609-00-3) → pyran-2-one (504-31-4)

Conditions	Yield
Multi-step reaction with 2 steps 1: 94 percent / 33percent hydrogen peroxide, 0.2 N sodium hydroxide / methanol; CH2Cl2; H2O / 3 h 2: 1.5 h / 0.04 Torr / flash vacuum thermolysis; T1 75 deg C / T2 375 deg C View Scheme

3,4-dihydro-2H-pyran (110-87-2) → pyran-2-one (504-31-4)

Conditions	Yield
Multi-step reaction with 4 steps 1: 6 percent / piridinium dichromate / CH2Cl2 / 2 h / 0 °C 2: 0.025 g / triethylamine / toluene / 0.5 h / 80 °C 3: NBS 4: triethylamine View Scheme
Multi-step reaction with 3 steps 1: 50 percent / piridinium dichromate / CH2Cl2 / 2 h / 0 °C 2: NBS 3: triethylamine View Scheme
Multi-step reaction with 4 steps 1: 6 percent / piridinium dichromate, t-butyl hydroperoxide / CH2Cl2 / 2 h / 0 °C 2: 0.025 g / triethylamine / toluene / 0.5 h / 80 °C 3: NBS 4: triethylamine View Scheme
Multi-step reaction with 3 steps 1: 50 percent / piridinium dichromate, t-butyl hydroperoxide / CH2Cl2 / 2 h / 0 °C 2: NBS 3: triethylamine View Scheme

2-(tert.butylperoxy)-3,4-dihydropyran (70411-95-9) → pyran-2-one (504-31-4)

Conditions	Yield
Multi-step reaction with 3 steps 1: 0.025 g / triethylamine / toluene / 0.5 h / 80 °C 2: NBS 3: triethylamine View Scheme

5,6-dihydro-pyran-2-one (3393-45-1) → pyran-2-one (504-31-4)

Conditions	Yield
Multi-step reaction with 2 steps 1: NBS 2: triethylamine View Scheme

pyran-2-one (504-31-4) → 5-oxabicyclo<2.2.0>hex-2-en-6-one (22980-23-0)

Conditions	Yield
In diethyl ether at -15℃; Inert atmosphere; Irradiation;	100%
In diethyl ether at -10℃; for 24h; Inert atmosphere; Irradiation;	100 %Spectr.
In diethyl ether at -10℃; UV-irradiation; Inert atmosphere;
In diethyl ether at -10℃; Inert atmosphere; Microwave irradiation;
In diethyl ether at -15℃; Inert atmosphere; Irradiation;

pyran-2-one (504-31-4) + decacarbonyl-1κ(4)C,2κ(3)C,3κ(3)C-μ-hydrido-2:3κ(2)H-μ-hydroxy-2:3κ(2)O-trisosmium-(3 Os-Os) → Os3(CO)10(μ-H)(μ-OH)*α-pyrone

Conditions	Yield
In hexane ligand was added to hexane soln. of Os-cluster in Schlenk tube, heated at 40°C for 2 h under N2; solvent was removed under reduced pressure, recrystd. from CH2Cl2/hexaneat -5°C; elem. anal.;	99%

N-phenyl-maleimide (941-69-5) + pyran-2-one (504-31-4) → N,N'-diphenylbicyclo<2.2.2>oct-7-ene-2,3,5,6-tetracarboxydiimide (64856-70-8, 97643-47-5)

Conditions	Yield
In decalin for 1.5h; Heating;	98%

pyran-2-one (504-31-4) → 5,6-dibromo-5,6-dihydro-2H-pyran-2-one (22682-17-3)

Conditions	Yield
Stage #1: pyran-2-one With bromine In dichloromethane at -78℃; for 5h; Inert atmosphere; Irradiation; Stage #2: In dichloromethane at -78 - 20℃; Inert atmosphere;	97%
With bromine In dichloromethane at -78℃; for 6h; Cooling with acetone-dry ice; Irradiation;	97%
With bromine Irradiation;

pyran-2-one (504-31-4) + [sodium phosphaethynolate•(dioxane)2.5] → C5H4OP(1-)*Na(1+)*C5H5OP*C4H8O2

Conditions	Yield
In 1,2-dimethoxyethane at 60℃; for 4h; Inert atmosphere;	97%

pyran-2-one (504-31-4) + allyl acrylate (999-55-3) → 3-Oxo-2-oxa-bicyclo[2.2.2]oct-7-ene-6-carboxylic acid allyl ester (134870-02-3, 134932-34-6, 144489-99-6, 144490-01-7)

Conditions	Yield
under 14251100 Torr; for 24h;	95%

pyran-2-one (504-31-4) + N,N-diallylacrylamide (3085-68-5) → 3-Oxo-2-oxa-bicyclo[2.2.2]oct-7-ene-6-carboxylic acid diallylamide (134870-04-5, 134932-36-8)

Conditions	Yield
under 14251100 Torr; for 24h;	95%

methanethiosulfonic acid S-methyl ester (2949-92-0) + pyran-2-one (504-31-4) → 6-(methylthio)-2H-pyran-2-one

Conditions	Yield
Stage #1: pyran-2-one With 2,2,6,6-tetramethylpiperidinylmagnesium chloride lithium chloride complex In tetrahydrofuran at -40℃; for 0.25h; Schlenk technique; Inert atmosphere; Stage #2: methanethiosulfonic acid S-methyl ester In tetrahydrofuran at -40 - 25℃; Schlenk technique; Inert atmosphere; regioselective reaction;	95%

pyran-2-one (504-31-4) → 2-oxa-3-oxobicyclo[2.2.0]hex-5-ene (22980-23-0)

Conditions	Yield
In diethyl ether at -15℃; UV-irradiation;	95%

pyran-2-one (504-31-4) + 3,3,4,4,7,7,8,8-octamethyl-3,4,7,8-tetrasilylcycloocta-1,5-diyne (85263-68-9) → 1,1,2,2,9,9,10,10-octamethyl-1,2,9,10-tetrasila<2.2>ortocyclophane (85263-70-3)

Conditions	Yield
With triethylamine In toluene	93%

maleic anhydride (108-31-6) + pyran-2-one (504-31-4) → 3-Oxo-2-oxabicylo<2.2.2>oct-7-en-exo-5,exo-6-dicarbonsaeureanhydrid (1515-21-5, 26290-47-1)

Conditions	Yield
In toluene at 55℃; under 3375270 Torr; for 12h;	92%
In toluene at 20 - 110℃; Diels-Alder reaction;	79%
In xylene at 90.5℃; Rate constant; Thermodynamic data; ΔH(excit.), ΔS(excit.); further temp.;
With toluene

pyran-2-one (504-31-4) + benzyl vinyl ether (935-04-6) → (1R,4R,8R)-8-Benzyloxy-2-oxa-bicyclo[2.2.2]oct-5-en-3-one

Conditions	Yield
With (+)-Yb(tfc)3 In neat (no solvent) for 72h; Product distribution; Ambient temperature; further Lewis acids, also in solvent; other benzylic vinyl ether; variation of excess of benzyl vinyl ether;	91%
With (+)-Yb(tfc)3 In neat (no solvent) for 72h; Ambient temperature;	91%

pyran-2-one (504-31-4) + 2,2-dimethylpropylidynephosphine (78129-68-7) → 2-tert-Butyl-λ3-phosphinin (109827-19-2)

Conditions	Yield
In benzene at 120℃; under 1875.1 - 2250.2 Torr; for 48h;	91%

cyclooctyne (1781-78-8) + pyran-2-one (504-31-4) → 5,6,7,8,9,10-hexahydrobenzocyclooctene (1076-69-3)

Conditions	Yield
for 72h; Ambient temperature;	88%

pyran-2-one (504-31-4) + benzyl vinyl ether (935-04-6) → 8-Benzyloxy-2-oxa-bicyclo[2.2.2]oct-5-en-3-one

Conditions	Yield
With (+)-Yb(tfc)3 In dichloromethane under 9000720 Torr; for 72h; Ambient temperature;	88%

pyran-2-one (504-31-4) + fumaryl dichloride (627-63-4) → 3-Oxo-2-oxabicyclo<2.2.2>oct-7-en-endo-5,exo-6-bis(carbonylchlorid) (82313-26-6)

Conditions	Yield
In toluene at 60℃; under 4125330 Torr; for 12h;	86%

pyran-2-one (504-31-4) + endo-tricyclo<4.2.2.02,5>deca-3,9-diene-7,8-dicarboxylate anhydride (51447-09-7) → C28H24O6 (77884-58-3)

Conditions	Yield
In xylene for 2h; Heating;	86%

pyran-2-one (504-31-4) + 4,4,5,5-tetramethyl-2-trimethylsilanylethynyl-[1,3,2]dioxaborolane (159087-46-4) → trimethyl(2-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)silane (910875-07-9)

Conditions	Yield
at 170℃; for 15h;	86%
In neat (no solvent) 1.5 equiv. of B compd., sealed, heated at 170°C for 17 h;	86%
In 1,3,5-trimethyl-benzene 1.5 equiv. of B compd., sealed, heated at 170°C for 17 h;	64%
In 1,3,5-trimethyl-benzene at 140°C for 48 h;	56%
In diphenylether 1.5 equiv. of B compd., sealed, heated at 170°C for 17 h;	56%

tetrafluoroboric acid diethyl ether (67969-82-8) + pyran-2-one (504-31-4) + (η5-C5H5)(Me)(NO)(PPh3)rhenium(II) → {(C5H5)Re(NO)(P(C6H5)3)(OC5H4O)}(1+)*BF4(1-)={(C5H5)Re(NO)(P(C6H5)3)(OC5H4O)}BF4

Conditions	Yield
In dichloromethane soln. of complex cooled to -80°C, addn. of B-compd. with stirring, addn. of ligand after 5 min, warmed to 0°C over the course of 2h, kept at 0°C for 1h; concd. (vac.), dropwise addn. of ether, filtered, washed (ether), dried (vac.); elem. anal.;	86%

pyran-2-one (504-31-4) + methylmagnesium bromide (75-16-1) → sorbic acid (5309-56-8)

Conditions	Yield
With iron(III)-acetylacetonate In diethyl ether at -30℃; Inert atmosphere;	86%

N-phenyl-maleimide (941-69-5) + pyran-2-one (504-31-4) → endo,endo-bis-N-phenylimide of bicyclo<2.2.2>oct-7-ene-2,3,5,6-tetracarboxylic acid (64856-70-8, 97643-47-5)

Conditions	Yield
In xylene at 140℃;	85%

pyran-2-one (504-31-4) + 1-methyl-4-(trimethylsilyl)-1H-indol-5-yl trifluoromethanesulfonate (1121707-11-6) → 3-methyl-3H-benzo[e]indole (23840-48-4)

Conditions	Yield
With cesium fluoride In acetonitrile at 100℃; for 5h; Inert atmosphere;	85%
With cesium fluoride In acetonitrile at 100℃;	85%

pyran-2-one (504-31-4) + hept-6-en-1-ylmagnesium bromide (154920-12-4) → (-)-(R)-4-(hept-6-en-1-yl)-3,4-dihydro-2H-pyran-2-one (1417889-31-6)

Conditions	Yield
Stage #1: hept-6-en-1-ylmagnesium bromide With copper(I) bromide dimethylsulfide complex; (R,S)-reverse-Josiphos In diethyl ether; tert-butyl methyl ether at -72℃; for 0.25h; Inert atmosphere; Schlenk technique; Stage #2: pyran-2-one In diethyl ether; tert-butyl methyl ether at -72℃; Inert atmosphere; Schlenk technique; enantioselective reaction;	85%

pyran-2-one (504-31-4) + dimethyl acetylenedicarboxylate (762-42-5) → phthalic acid dimethyl ester (131-11-3)

Conditions	Yield
at 200℃; for 2h;	84%

pyran-2-one (504-31-4) + methyl 2-(7-hydroxy-3-methyl-5-(triflyloxy)bicyclo[4.2.0]octa-1,3,5-trien-7-yl)acetate → methyl 4-(1-(3-methylnaphthyl))-3-oxobutanoate

Conditions	Yield
With potassium carbonate In acetonitrile at 20℃; for 12h; Inert atmosphere;	82%

pyran-2-one (504-31-4) + (3-methylphenyl)(6-methyl-2-pyridyl)acetylene (74844-06-7) → 1-(3-methylphenyl)-2-(6-methyl-2-pyridyl)benzene (74844-07-8)

Conditions	Yield
With hydroquinone In 1,2-dichloro-benzene for 72h; Heating;	80%

Upstream product

• 672-67-3 2H-pyran-2-one-6-carboxylic acid 
• 500-05-0 2H-pyran-2-one-5-carboxylic acid 
• 53646-72-3 5-bromo-5,6-dihydro-2H-pyran-2-one 
• 19192-82-6 tricyclo<2^3,6.1.1.0>pyran-2-one 
• 19978-32-6 3-bromo-2H-pyran-2-one 
• 15681-48-8 lithium dimethylcuprate 
• 60249-17-4 6-methoxy-2H-pyran-3(6H)-one 
• 283156-10-5 3-bromo-6-methoxy-3,6-dihydro-2H-pyran 
• 25566-16-9 hexane-3,4-cis-diol-2,5-dione 
• 123-75-1 pyrrolidine 
• 136080-97-2 1-[2-(benzofurazan-5-yl)ethyl] piperidin-4-one 
• 7298-67-1 5-acetamido-2-hydroxyacetophenone 
• 3393-45-1 5,6-dihydro-pyran-2-one 
• 70411-95-9 2-(tert.butylperoxy)-3,4-dihydropyran 

Downstream Products

• 1515-21-5 3-Oxo-2-oxabicylo<2.2.2>oct-7-en-exo-5,exo-6-dicarbonsaeureanhydrid 
• 3573-76-0 (1r,2R,3S,4r,5R,6S)-bicyclo<2.2.2>oct-2-ene-2,3,5,6-tetracarboxylic bisanhydride 
• 29739-67-1 (Z)-penta-2,4-dienoic acid 
• 91-20-3 naphthalene 
• 17424-21-4 5-methyl-hexadien-trans-2,4-al 
• 18402-90-9 (3E,5E)-3.5-heptadien-2-one 
• 4173-40-4 3,5-heptadien-2-one 
• 92180-77-3 (E)-6-hydroxyhept-4-en-2-one 
• 64856-70-8 N,N'-diphenylbicyclo<2.2.2>oct-7-ene-2,3,5,6-tetracarboxydiimide 
• 64856-70-8 endo,endo-bis-N-phenylimide of bicyclo<2.2.2>oct-7-ene-2,3,5,6-tetracarboxylic acid 
• 74764-52-6 1,2-di(pyridin-2-yl)benzene 
• 82313-26-6 3-Oxo-2-oxabicyclo<2.2.2>oct-7-en-endo-5,exo-6-bis(carbonylchlorid) 
• 121-69-7 N,N-dimethyl-aniline 
• 71838-15-8 phenylene-1,2-diphosphonic acid tetraethyl ester 

Relevant articles and documents

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