2-aryl-5-(trifluoromethyl)-2-pyrroline compounds useful in the manufacture of insecticidal, nematocidal and acaricidal arylpyrroles

#Certain substituted arylpyrrole compounds and their use as insecticidal, acaricidal and nematocidal agents are described in copending U.S. application Ser. No. 392,495 filed on Aug. 11, 1989 which is a continuation-in-part of U.S. application Ser. No. 208,841 filed on Jun. 23, 1988 which is a continuation-in-part of U.S. application Ser. No. 079,545 filed on Jul. 29, 1987, now abandoned. A process for the preparation of 2-aryl-5-(trifluoromethyl)pyrrole compounds via an azalactone intermediate is described in copending U.S. application Ser. No. 560,396 filed on Jul. 31, 1990.

#It is an object of this invention to present more useful intermediates for the process of manufacture of a variety of insecticidal, acaricidal and nematocidal arylpyrrole compounds and a method for the preparation of said intermediates. Methods for the use of the pyrroline and glycine intermediates of the present invention in the process of manufacture of arylpyrrole insecticidal agents is described in copending U.S. application Ser. No. 07/634,287 filed concurrently herewith and incorporated herein by reference thereto.

#The present invention relates to compounds of formula I ##STR1## wherein A is hydrogen or C.sub.1 -C.sub.4 alkyl;

#A mixture of p-chlorobenzaldehyde (153 g, 1.0 mol) in tetrahydrofuran is treated with a solution of methylamine hydrochloride (88 g, 1.3 mol) in water followed by an aqueous solution of sodium cyanide (53 g, 1.0 mol), stirred at room temperature for 16 hours and extracted with toluene. The organic extract is treated with 10 cc of pyridine followed by 50 cc of acetic anhydride (exotherm), stirred at ambient temperatures for 1/2 hour and concentrated in vacuo to give an oil residue. The residue is added to a 1:1 mixture of water and concentrated hydrochloric acid, heated at reflux temperature for 2 hours, cooled, diluted with water and neutralized to about pH 2 with 50% NaOH solution. The resultant solid precipitate is filtered and air-dried to give the title product as a white solid, 180 g (89.5% yield), mp 208.degree.-213.degree. C.

#A mixture of 2-(p-chlorophenyl)sarcosine (27 g, 0.135 mol) in dry toluene is treated with 20 cc of trifluoroacetic anhydride, stirred for 1 hour and concentrated in vacuo to give a solid residue. The residue is re-evaporated several times with toluene to give the title product as a red solid, 38.7 g (97% yield), mp 117.degree.-118.degree. C., identified by NMR spectroscopy.

#A mixture of DL-phenylglycine (15.1 g, 0.10 mol) in methanol is treated with triethylamine (10.1 g, 0.10 mol) and ethyl trifluoroacetate (17.8 g, 0.125 mol), stirred at room temperature for 72 hours, diluted with methanol and treated with Dowex 50x8 acidic resin. The reaction mixture is stirred for 10 minutes and filtered. The filtrate is concentrated in vacuo to give a pale yellow solid which is recrystallized from 1,2-dichloroethane to give the title product as white needles, 10.5 g (42% yield), mp 155.degree.-157.degree. C.