Metal-free oxidation of pyrenes
View Patent ↗The present invention provides a method for oxidizing pyrenes without any metal-mediated catalyst or reagent. In particular, the present invention provides a method for selectively oxidizing the K-region of pyrenes using a meta-free oxidizing agent to produce a pyrene 4,5-dione and/or a pyrene 4,5,9,10-tetraone compounds.
1 . A process for oxidizing a pyrene compound according to Formula I:
the process comprising contacting the pyrene compound according to Formula I with a metal-free oxidizing agent under conditions sufficient to produce a pyrene 4,5-dione according to Formula II or a pyrene 4,5,9,10-tetraone compound according to Formula III:
wherein
each of R 1 and R 2 are independently an alkyl, an aryl, or a heteroaryl, and
the metal-free oxidizing agent comprises a hypervalent iodine oxyacid, a hypervalent iodine, or any mixture thereof.
2 . The process of claim 1 , wherein each of R 1 and R 2 are independently an alkyl selected from the group consisting of isopropyl, tert-butyl, sec-butyl, isobutyl, tert-pentyl, neopentyl, isopentyl, and sec-pentyl.
3 . The process of claim 1 , wherein each of R 1 and R 2 are independently an aryl or a heteroaryl.
4 . The process of claim 1 , wherein the process produces a pyrene 4,5-dione compound according to Formula II in a yield of greater than about 40%.
5 . The process of claim 4 , wherein the amount of the metal-free oxidizing agent used in the process ranges from more than about 2 molar equivalents to less than about 4 molar equivalents relative to the pyrene compound according to Formula I.
6 . The process of claim 1 , wherein the process produces a pyrene 4,5,9,10-tetraone compound according to Formula III in a yield of greater than about 40%.
7 . The process of claim 6 , wherein the amount of the metal-free oxidizing agent used is more than about 4 molar equivalents relative to the pyrene compound according to Formula I.
8 . The process of claim 1 , wherein said process the conducted using a solvent selected from the group consisting of alcohols, carboxylic acids, water, and any mixture thereof.
9 . The process of claim 8 , wherein the alcohols comprise ethanol, n-propanol, isopropanol, n-butyl alcohol, iso-butyl alcohol, t-butyl alcohol, sec-butyl alcohol, tert-pentyl alcohol, neopentyl alcohol, isopentyl alcohol, sec-pentyl alcohol, cyclopentanol, cyclohexanol, or any mixture thereof.
10 . The process of claim 8 , wherein the carboxylic acids comprise formic acid, acetic acid, propionic acid, butyric acid, pentanoic acid, cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, or any mixture thereof.
11 . The process of claim 1 , wherein the process is conducted using a solvent selected from the group consisting of alcohols, water, and any mixture thereof.
12 . The process of claim 1 , wherein the hypervalent iodine oxyacid comprises H 5 IO 6 , HIO 3 , HIO 4 , HIO 2 , HIO, or any mixture thereof.
13 . The process of claim 1 , wherein the hypervalent iodine comprises 2-iodoxybenzoic acid (IBX), Dess-Martin periodinane (DMP), iodosylbenzene, iodosylarene of the formula Ar—I═O, bis(acetoxy)iodobenzene, bis(acetoxyoxy)iodoarenes of the formula Ar—I(OCOCH 3 ) 2 , bis(trifluoroacetoxy)iodobenzene, bis(trifluoroacetoxyoxy)iodoarenes of the formula Ar—I(OCOCF 3 ) 2 , wherein
Ar is an unsubstituted aryl, or
Ar is an aryl substituted with one or more of the following substituents: a C 1 -C 8 alkyl, a C 1 -C 8 alkoxy, a halide, and an electron-withdrawing group.
14 . A method for producing a pyrene 4,5-dione compound according to Formula II from a pyrene compound according to Formula I, the method comprising:
contacting the pyrene compound according to Formula I;
with less than 6 molar equivalents of a metal-free oxidizing agent under conditions sufficient to produce the pyrene 4,5-dione compound according to Formula II:
wherein each of R 1 and R 2 are independently alkyl, aryl, or heteroaryl,
wherein the metal-free oxidizing agent comprises a hypervalent iodine oxyacid, a hypervalent iodine, or any mixture thereof.
15 . The method of claim 14 , wherein the method further comprises using a polar protic solvent.
16 . The method of claim 15 , wherein the polar protic solvent comprises an alcohol.
17 . The method of claim 16 , wherein the alcohol is selected from the group consisting of methanol, ethanol, isopropyl alcohol, or a mixture thereof.
18 . A method for producing a pyrene 4,5,9,10-tetraone compound according to Formula III from a pyrene compound according to Formula I, the method comprising:
contacting the pyrene compound according to Formula I:
with greater than 6 molar equivalents of a metal-free oxidizing agent under conditions sufficient to produce the pyrene 4,5,9,10-tetraone compound according to Formula III:
wherein each of R 1 and R 2 are independently alkyl, aryl, or heteroaryl, and
wherein the metal-free oxidizing agent comprises a hypervalent iodine oxyacid, a hypervalent iodine, or any mixture thereof.
19 . The method of claim 18 , wherein the method further comprises using an acidic solvent.
20 . The method of claim 19 , wherein the acidic solvent comprises a carboxylic acid solvent, a sulfonic acid, an organophosphonic acid, or any mixture thereof.
21 . The method of claim 20 , wherein the carboxylic acid solvent comprises formic acid, acetic acid, propionic acid, butyric acid, pentanoic acid, cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, or any mixture thereof.
22 . The method of claim 19 , wherein the acidic solvent comprises sulfuric acid, hydrochloric acid, nitric acid, phosphonic acid, chloric acid, perchloric acid, hydrobromic acid, hydroiodic acid, or any mixture thereof.
23 . The method of claim 14 , wherein
the hypervalent iodine oxyacid comprises H 5 IO 6 , HIO 3 , HIO 4 , HIO 2 , HIO, or any mixture thereof, and/or
the hypervalent iodine comprises 2-iodoxybenzoic acid (IBX), Dess-Martin periodinane (DMP), iodosylbenzene, iodosylarene of the formula Ar—I═O, bis(acetoxy)iodobenzene, bis(acetoxyoxy)iodoarenes of the formula Ar—I(OCOCH 3 ) 2 , bis(trifluoroacetoxy)iodobenzene, bis(trifluoroacetoxyoxy)iodoarenes of the formula Ar—I(OCOCF 3 ) 2 , wherein
Ar is an unsubstituted aryl, or
Ar is an aryl substituted with one or more of the following substituents: a C 1 -C 8 alkyl, a C 1 -C 8 alkoxy, a halide, and an electron-withdrawing group.
24 . The method of claim 18 , wherein
the hypervalent iodine oxyacid comprises H 5 IO 6 , HIO 3 , HIO 4 , HIO 2 , HIO, or any mixture thereof, and/or
the hypervalent iodine comprises 2-iodoxybenzoic acid (IBX), Dess-Martin periodinane (DMP), iodosylbenzene, iodosylarene of the formula Ar—I═O, bis(acetoxy)iodobenzene, bis(acetoxyoxy)iodoarenes of the formula Ar—I(OCOCH 3 ) 2 , bis(trifluoroacetoxy)iodobenzene, bis(trifluoroacetoxyoxy)iodoarenes of the formula Ar—I(OCOCF 3 ) 2 , wherein
Ar is an unsubstituted aryl, or
Ar is an aryl substituted with one or more of the following substituents: a C 1 -C 8 alkyl, a C 1 -C 8 alkoxy, a halide, and an electron-withdrawing group.