Perchlorates, substituted amines

S-Substituted thiiranium ions react with secondary amines to give ring-opened products. Nitriles also react with thiiranium ions, probably via an open carbenium ion whose formation is favored by increasing the polarity of the medium by the addition of lithium perchlorate (Scheme 79) (79ACR282). An intramolecular displacement by an amide nitrogen atom on an intermediate thiiranium ion has been invoked (80JA1954). 

Reactions of Enamine Salts with OrganometalUc Compounds Organolithium and organomagnesium compounds react with enamine salts to give amines substituted on the ix-carbon atoms. The treatment of. -dehydroquinolizidinium perchlorate (163) with alkylmagnesium halides gives 9-alkylated quinolizidines (164) (252,256). Formation of... 

Phenyl 2,6-dinitro-4-trifluoromethylphenyl sulphide. Chamberlain and Crampton130 studied also the reaction of phenyl 2,6-dinitro-4-trifluoromethylphenyl sulphide with amines in DMSO. They observed a single rate process with butylamine giving the expected substituted product again, the observed rate constant increased with [butylamine]. In the reaction with pyrrolidine a rapid reaction giving the 3-pyrrolidino adduct was observed, which could be suppressed by addition of pyrrolidinium perchlorate. Under these conditions the expected 1-substituted product was formed. 

The reaction of several amines with 7-methoxy-3-phenylbenzopyrylium perchlorate has been shown to yield the corresponding 2-substituted 3-phenylchromene (78JCS(P1)88), although the reaction of secondary amines with simple benzopyrylium salts gives mixtures of chrom-3-enes and chrom-2-enes (72JOC1069). 

The pyridinium perchlorate (212), which is the precursor of the mesoionic oxazolone (213), is formed by the action of acetic anhydride and perchloric acid on l,2-dihydro-2-oxopyridin-l-acetic acid. The mesoion (213) is chemically unstable and is generated in solution for its reactions by treatment with a tertiary amine. Compound (213) is easily substituted at C-3, and with trifluoroacetic anhydride forms the stable 3-trifluoroacetyl mesoion (70JCS(C)1485). 

Tertiary amines form complexes with mercury(II) ion, which then give iminium ions by loss of a piotoa Addition of perchloric acid permits isolation of the iminium ion as the perchlorate salt and generally the more-substituted ion is favored (equation 14). Intramolecular trapping by a hydroxyalkyl group is also possible to form aminals (equation 15). The lactam products result from over-oxidation, which is promoted by heat. Basification on the other hand usually allows the isolation of enamines although hydroxyenamines have been obtained by reaction of enamines with mercury(II) acetate (equation 16), while dihydroaromatic systems undergo aromatization (equation 17). ... 

Analogous to epoxides, aziridines can be prepared by the methylenation of imines. In this case, ethyl diazoacetate is the most common source of carbenes. For example, the imine derived from p-chlorobenzaldehyde 148 is converted to the c/j-aziridinyl ester 149 upon treatment with ethyl diazoacetate in the presence of lithium perchlorate <03TL5275>. These conditions have also been applied to a reaction medium of the ionic liquid l-n-butyl-3-methylimidazolium hexafluorophosphate (bmimPFe) with excellent results <03TL2409>. An interesting enantioselective twist to this protocol has been reported, in which a diazoacetate derived from (TJ)-pantolactone 150 is used. This system was applied to the aziridination of trifluoromethyl-substituted aldimines, which were prepared in situ from the corresponding aminals under the catalysis of boron trifluoride etherate <03TL4011>. 

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