Process for synthesis of 5-alkylbenzodioxoles

Details Process for synthesis of 5-alkylbenzodioxoles Process for synthesis of 5-alkylbenzodioxoles

2000-04-13

2001-06-26

McKane, Joseph K. (Department: 1626)

Organic compounds -- part of the class 532-570 series

Organic compounds

Heterocyclic carbon compounds containing a hetero ring...

Reexamination Certificate

active

06252092

ABSTRACT:

FIELD OF THE INVENTION
The present invention belongs to the field of the synthesis of benzodioxole derivatives, which are particularly useful in perfumery and in the manufacture of insecticides.
PRIOR ART
Various natural substances, such as flavones and alkaloids, which contain the methylenedioxy-1,2-benzene group (also known as benzo[1,3]dioxole) are biologically active. For example, benzo[1,3]dioxole derivatives are used to treat liver disorders (
Chem. Abstracts,
1990, 113: 52534).
Said derivatives have found extensive application in perfumery and in the manufacture of flavours and insecticides. Compounds containing the benzo[1,3]dioxole group, which show insecticide action, have been described in several publications (cf. e.g.
Bull. Soc. Chim. France,
1964,1892-1895).
Particularly interesting are the 5-substituted benzo[1,3]dioxole derivatives, such as for example 5-(2-propenyl)-benzo[1,3]dioxole (safrole), a constituent of many essential oils and one of the chief constituents of sassafras oil (75% approx.) (Oswald et al.,
Biochim. Biophys. Acta,
1971, 230, 237). A further important 5-substituted derivative is 5-(1-propenyl)-benzo[1,3]dioxole (isosafrole), an essence used in perfumery and as a deodoriser for soap. Isosafrole is also used in the synthesis of piperonal (heliotropin, benzo[1,3]dioxole-5-carboxyaldehyde), another essence utilised in the perfume and flavour industry. Also 5-hydroxymethyl-benzo[1,3]dioxole (piperonyl alcohol) and derivatives thereof are of most interest for the aforesaid industrial areas.
Particularly interesting are the benzo[1,3]dioxoles substituted in position 5 with an alkyl group, since they may be used as key reagents in the synthesis of the aforementioned products of industrial importance as well as of other products, such as piperonyl butoxide, an active ingredient exhibiting insecticide action. Furthermore, 5-alkylbenzo[1,3]dioxoles, on their own, show biological activity as inhibitors of liver enzymes (
Shashpa,
1994 (1)1, 47-52).
Therefore, the need for effective processes for the synthesis of 5-allylbenzo[1,3]dioxoles is deeply felt.
Typically, the formation of the benzo[1,3]dioxole ring is obtained by causing catechol (1,2-dihydroxybenzene) to react with methylene halides (e.g. CH
2
Cl
2
) in a dipolar aprotic solvent and in a basic environment (
Tetrahedron Lett.
1991, 32 (22), p. 2464). Unfortunately, this reaction to yield 5-alkylated benzo[1,3]dioxole can be hardly exploited in indusrtial-scale plants: in fact, the high cost of 4-alkylcatechols, which are required for the synthesis of said derivatives, makes said synthesis economically unprofitable. This problem cannot be solved by a direct synthesis 4-alkylcatechols, as it produces a mixture of undesired isomers (J. March,
Advanced Organic Chemistry
, McGraw-Hill Inc., 1968, 406-409) or requires the use of reagents in particularly severe conditions, e.g. hydrofluoric acid in the liquid state (CS-160524), which factors increase the process cost.
In view of the foregoing limitations, there is an urgent need for identifying an effective route for the synthesis of 5-alkylated benzo[1,3]dioxoles. In particular, the synthesis to be developed must be little expensive and easily reproducible on a industrial scale.
SUMMARY
It has surprisingly been found a process for the synthesis of 5-alkylated benzo[1,3]dioxoles, which makes up for the aforesaid cons. Said process comprises the following steps in sequence: catalytic hydrogenation of 4-acylphenol; acylation; displacement catalysed by Lewis acids; treatment with an inorganic basic compound and hydrogen peroxide; reaction with alkyl dihalides or dialkoxyalkanes.
The process described herein, which yields 5-alkylbenzo[1,3]dioxoles, is economic and can be easily scaled up to industrial size.


REFERENCES:
“Para-Selective Fries Rearrangement of Phenyl Acetate in the Presence of Zeolite Molecular Sieves”,Tetrahedron Letters, vol. 30, No. 17, pp. 2281-2284, (1989).
“Substitucion Der Carbonyl-Gruppo Durch Die Hydroxy-Gruppe”,Hauben Weil, E-3 (1983).
C. DevaKumar, “Insect Growth Disrupting Effects of Some 1,3-Benzodioxoles”,Shashpa1 (1): 47-52 (1994).

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