Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Patent
1998-12-14
1999-12-28
Owens, Amelia
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
C07D31104
Patent
active
060083816
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a chemical process and more particularly to a process for preparing 3-isochromanone which is useful in the manufacture of certain agricultural products. 3-Isochromanone is a well known compound and a number of methods for its preparation are described in the chemical literature. For example, it can be prepared by (i) the Baeyer-Villiger oxidation of 2-indanone using hydrogen peroxide in sulphuric acid and acetic anhydride (Syn.Commun. 2 [1972], 139; Synthesis [1973], 107) or using 3-chloroperoxybenzoic acid combined with trifluoroacetic acid (Syn.Commun. 9 [1989], 829); (ii) from 2-methoxycarbonylmethylbenzoic acid by (a) treatment with ethylchloroformate in triethylamine and (b) sodium borohydride (Chem. Pharm. Bull.) 16 [1968], 492, 496); or (iii) from isochroman-3-ol and chromium trioxide (Tet.lett. [1973], 2359). It is also known to prepare 3-isochromanone by the bromination of o-tolylacetic acid with N-bromosuccinimide followed by ring closure by boiling the 2-bromomethylphenylacetic acid so formed with potassium hydroxide in ethanol (Zh.Org.Khim. [1973] 9 (10), 2145-9). A disadvantage of this process is the expensive source of halogen, which makes it unattractive on an industrial scale.
According to one aspect of the present invention there is provided a process for the preparation of 3-isochromanone which comprises the steps: a free radical initiator; and
The process is represented by the following reaction scheme: ##STR1##
Step (a) of the process is conveniently carried out in a solvent which is inert to the reactants, for example, an aromatic hydrocarbon such as benzene or a halogenated aromatic hydrocarbon such as fluorobenzene or chlorobenzene, at an elevated temperature, suitably from 50.degree. C. to 90.degree. C., for example, from 60.degree. C. to 80.degree. C.
Any amount of sulphuryl chloride may be used but, for efficiency, it is desirable to use at least one mole of sulphuryl chloride per mole of o-tolylacetic acid and preferably a molar excess up to 1.5 moles per mole, for example, up to 1.2 moles per mole. Typically, around 1.1 mole of sulphuryl chloride per mole of o-tolylacetic acid is used.
The free radical initiator may be a suitable source of heat or light or a chemical compound of a type used to initiate free radical reactions, such as a peroxide, a peracid or an azo compound. Particularly suitable is 2,2'-azobisisobutyronitrile (AIBN). The quantity of AIBN used is typically from 0.01 to 0.1 moles per mole of o-tolylacetic acid, for example from 0.01 to 0.05 moles per mole.
Any suitable base may be used in step (b) of the process for example an alkali metal or alkaline earth metal hydroxide, such as sodium or potassium hydroxide. However, it is an advantage of the present process that a mild base such as an alkali metal bicarbonate, for example, potassium bicarbonate, can be used. In this case it may be helpful to use a catalyst to assist ring closure of the 2-chloromethylphenylacetic acid. Thus, a catalytic amount of an iodide, such as an alkali metal iodide, typically potassium iodide, has been found particularly useful. To avoid problems with product crystallisation, it is sensible to treat the product of step (a) with the base at a temperature of from 40.degree. C. to 80.degree. C., suitable from 50.degree. C. to 70.degree. C., a typically at about 60.degree. C.
Both steps of the process are novel and individually form part of the present invention.
Thus, according to another aspect of the present invention there is provided a process for the preparation of 2-chloromethylphenylacetic acid which comprises reacting o-tolylacetic acid with sulphuryl chloride in the presence of a free radical initiator.
Suitably the reaction is carried out in a halogenated aromatic hydrocarbon solvent, for example, fluorobenzene solvent, at a temperature of from 50.degree. C. to 90.degree. C., for example from 60.degree. C. to 80.degree. C.
The amount of sulphuryl chloride used is suitably in the range of from 1 to 1.2 moles per mole of o-tolylacetic acid. The free radica
REFERENCES:
Spangler, R.J. et al, The Pyrolysis of Isochroman-3-one. A Convenient Synthesis of Benzocyclobutene, Communications, pp 107-108 (Feb. 1973).
J. H. Markgraf et al., 3-Isochromanone, Synthetic Communications, pp 139-41 (1972).
Koch, Stacie S. Canan et al, Modified Conditions for Efficient Baeyer-Villager Oxidation With m-CPBA, Synthetic Communications, pp 829-31 (1989).
G. Kraiss et al, Selective Reduction of Diethyl Homophthalate With Diisobutylaluminium Hydride, Tetrahedron Letters, No. 26, pp 2359-60 (May 1973).
V.B Milevskaya et al, Journal of Organic Chemistry, vol. 9, No. 10, Reaction of Homophthalic Acid with Phosphorus Pentachloride, pp 2160-62 (Oct., 1973).
Kikuo Ishizumi et al, Chemistry of Sodium Borohydride and Diborane, IV.sup.1) Reduction of Carboxylic Acids to Alcohols with Sodium Borohydride through Mixed Carbonic-Carboxylic Acid Anhydrides.sup.2), Chem. Pharm. Bull., vol. 16, pp. 492-97 (1968).
Chemical Abstracts, vol. 80, No. 7, 36954e (1974).
Chemical Abstracts, RN 95335-46-9 (1997).
Foster Nicholas Russell
Jones Raymond Vincent Heavon
Standen Michael Charles Henry
Williams Alfred Glyn
LeCroy David P.
Owens Amelia
Zeneca Limited
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