Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Patent
1994-09-20
1996-10-29
Barts, Samuel
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
549550, 549549, 546336, 546346, 560 20, 558250, 558257, 564160, C07D30338
Patent
active
055697747
DESCRIPTION:
BRIEF SUMMARY
This application was filed under USC 371 from the application PCT/EP 93/00586 filed Mar. 13, 1993 and published as WO93/19034 Sep. 30, 1993.
DESCRIPTION
The present invention relates to a novel process for preparing chlorine-substituted olefins of the general formula I ##STR3## where R.sup.1 is a C-organic radical and R.sup.2 is one of the following groups: --CN, --CO--R.sup.3, --CO--S--R.sup.3, --CO--O--R.sup.3 or --CO--NR.sup.4 R.sup.5, where R.sup.3 is a C-organic radical and R.sup.4 and R.sup.5 are each hydrogen or a C-organic radical.
Several methods are known for preparing .alpha.-chlorocinnamic esters as compounds I (R.sup.1 =phenyl; R.sup.2 =--COOR.sup.3) but are unsatisfactory in various respects. Thus, it is possible first to add chlorine on to the double bond of the appropriate cinnamic ester and to eliminate hydrogen chloride from the .alpha.,.beta.-dichlorinated 2-phenylpropionic esters (cf. for example, J. March, Advanced Organic Chemistry, McGraw Hill International Book Company, Aukland, 2nd ed., 1977, pages 739 et seq.). The disadvantage of this is that the selectivity of the reaction is poor.
Another method comprises reacting benzaldehyde (or a substituted benzaldehyde) with method (G. Wittig, G. Geisler, Liebigs Ann. Chem. 44 (1953) 580 and G. Markl, Chem. Ber. 94 (1961) 2996) or method (Horner, Hoffmann, Wippel, Chem. Ber. 91 (1958) 61; Horner, Hoffmann, Wippel, Klahre, Chem. Ber. 92 (1959) 2499 and McKenna, Khawli, J. Org. Chem. 51 (1986) 5467).
However, this procedure has disadvantages, not least in respect of technical difficulties.
It is furthermore known that the action of phosgene, phosphorus oxychloride, or phosphorus trichloride or pentachloride on oxiranes of the formula II' ##STR4## where R.sup.a and R.sup.b are each hydrogen, alkyl or phenyl or together are a carbocyclic ring, inter alia in excess dimethylformamide, results in 1,2-dichloro compounds (W. Ziegenbein, K. -H. Hornung, Chem. Ber. 95 (1962) 2976).
In accordance with the teaching of DE-A 10 96 899 the reaction of aliphatic or cycloaliphatic 1,2-epoxides, which may carry aryl or aralkyl substituents, with adducts of phosphorus oxychloride or phosgene and an N,N-dialkylamide and subsequent hydrolysis yields 1-acyloxy-2-chloroalkyl derivatives of alkanes or cycloalkanes.
It was an object of the present invention to provide a simple and industrially economic method starting from low-cost compounds which are easy to manipulate industrially for preparing the chlorine-substituted olefins I.
Accordingly, we have found that this object is achieved by a process for preparing chlorine-substituted olefins of the formula I, which comprises reacting an oxirane of the formula II ##STR5## in the presence of a carboxamide (IIIa) or of a lactam (IIIb) in liquid phase with a chlorinating agent (IV).
We have also found novel oxiranes of the general formula IIa ##STR6## where R.sup.2' is cyano, C.sub.1 -C.sub.6 -alkylcarbonyl, C.sub.1 -C.sub.6 -alkoxycarbonyl or C.sub.1 -C.sub.6 -alkylthiocarbonyl.
The oxiranes of the formula II used as starting materials can be prepared by methods known per se (e.g. M. S. Newman, B. J. Magerlein, Org. React. 5 (1949) 413).
The novel oxiranes IIa are preferably obtained by reacting 2-chloro-5-nitrobenzaldehyde with a derivative of the formula L--CH.sub.2 --R.sup.2' where L is a nucleophilic leaving group, especially chlorine.
The reaction is carried out in an inert solvent or diluent in the presence of a strong base, for example an alkali metal alcoholate such as sodium methylate.
Particularly suitable solvents or diluents are lower alcohols such as methanol, ethanol and isopropanol. It is expedient to use the alcohol whose alcoholate comprises the base.
The reaction is generally carried out at from 0.degree. to 40.degree. C.
As a rule, the reaction is carried out under atmospheric pressure or under the autogenous pressure of the solvent used.
The chlorination according to the invention of the oxiranes II is carried out in the presence of a carboxamide or of a lactam, and examples of compounds which h
REFERENCES:
patent: 5198557 (1993-03-01), Giordano et al.
J. March, Adv. Org. Chem., Auckland, 2nd Ed., 1977, p. 739ff.
G. Wittig et al., Liebigs Ann. Chem., 44, p. 580 (1953).
G. Markl, Chem. Ber., 94, p. 2996 (1961).
Horner et al., Chem. Ber., 91, p. 61, (1958).
Horner et al., Chem. Ber., 92, p. 2499 (1959).
McKenna et al., J. Org. Chem., 51, p. 5467 (1986).
Ziegenbein et al., Chem. Ber., 95, p. 2976 (1962).
Newman et al., Org. React., 5, p. 413 (1949).
Schaefer Bernd
Troetsch-Schaller Irene
Barts Samuel
BASF - Aktiengesellschaft
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