Methyleneamines

Primary and secondary amines readily give alkylaminomethanols the latter condense upon heating or under alkaline conditions to give substituted methyleneamines (59). With ammonia, the important industrial chemical, hexamine, is produced. Tertiary amines do not react. 

We have conducted the comparative study of gold (III), platinum (IV) and palladium (II) acidocomplexes solution on macroporous granular sorbents on the basis of polystyrene with functional groups of methyleneamine, 3-methylpyrasolyl, N,N-dimethylaminomethylene, dimethylmethylene-P-oxyethylamine and with functional 6-(3-methylpyridine) groups on polyvinylpyridine basis as well as fibrous polystyrene sorbent with pyrazolyl groups. 

Gold (III) and palladium (II) are sorbed quantitatively on all studied sorbents, except for methyleneamine, from solutions 0,2-2 M HCI. The degree of platinum (IV) complex extraction substantially depends not only on the nature of sorbent functional groups, but also on geometrical parameters of the matrix. This factor influences gold (III) and palladium (II) soi ption to a lesser extent. 

Strong acids produce salts of the primary amines alkalis or ammonia give the corresponding methyleneamines.)... 

An AMI semiempirical method was used to investigate the Diels-Alder cycloaddition reactions of vinyl sulfenes with buta-1,3-dienes.156 The reactivity and stereoselectivity of vinyl boranes have been reviewed.157 Aromatic methyleneamines undergo reverse-electron-demand Diels-Alder reactions with cyclopentadiene, norbom-ene, and vinyl sulfides.158... 

Azole approach. The substituted isothiazole (142) can be reacted with an ortho ester to form a methyleneamine which reacts with hydroxylamine to yield the 5-oxide (143). With amidines, (142) yields 4-amino derivatives (75JHC883). The reaction of 5-amino-4-ethoxycar-bonylisothiazole with iminoethers results in pyrimidine annulation, as in the formation of... 

N-Bis(methylthio)methylene derivatives of amines (iminodithiocarbonates) were first introduced by Hoppe and Beckmann468 for the synthesis of a-amino acids from glycine. The A bis(methylthio)methyleneamines are prepared by reaction of a primary amine with carbon disulfide (HAZARD) in the presence of triethylamine and iodomethane to form a methyl dithiocarbamate derivative, which is then S-alkylated with a second equivalent of iodomethane in the presence of potassium carbonate as the base. Scheme 8,233 illustrates an alternative one pot procedure applied to the synthesis of /erf-butyl N-[bis(methylthio)-methylene]glycinate and its use in diastereoselective conjugate addition under... 

Cyclization of 24 with AI-cyano-bis(methylthio)methyleneamine 29 and primary amines gave the corresponding 2-cyanoamino-4-oxo derivatives 30 (R = CN) [87EGP(D)249023 93PHA347]. 

A second problem with experimental results is that, as with theoretical methods, different experimental techniques can give somewhat different results. This is illustrated in Table II, which lists three sets of experimental data for methyleneamine, differing among themselves by as much as 0.2 eV. 

Synthetic applications of Lewis acid-induced hexahydro-l,3,5-triazines as A-methyleneamine equivalents 02H(57)1525. 

An in situ method for the preparation of N-methyleneamines has been devised by Overman and Osawa for use in condensation reactions with enolates and organometallic reagents. These species, with the exception of very hindered N-methyleneamines, cannot be isolated in the condensed phase because they rapidly trimerize to hexahydro-l,3,5-triazines. In this in situ method, A -methyleneamines (230) are generated from N-(cyanomethyl)amines (228) by deprotonation with an equivalent of enolate to give an intermediate amide (229) which loses LiCN (equation 22). When two equivalents of enolate are present, addition to the N-methyleneamine occurs and 3-lactams (233) are obtained in 60-70% yield upon warming the reaction mixture to 25 C (Scheme 48 Table 26). Uncyclized 3-amino esters can be isolated if the reaction is quenched at lower temperature a possible cycloaddition mechanism is thus ruled out. It is not clear to what extent, if any, the reaction is limited to a,a-disubstituted enolates. N-Methyleneamines, like oxime ethers, are useful for the synthesis of 4-unsubstituted 3-lactams and should also have important applications in the synthesis of monobactam antibiotics. 

Table 26 -Lactam-forming Reactions of Enolates of Ester (231) and /V-Methyleneamines Prepared In Situ from...

Lewis acid was used to produce JV-methyleneamine equivalents from (94) which react with trialkyl phosphites to give (95) and with TMS-CN to give aminoacetonitriles (96) <90MI 612-04, 9isci55>. Ketene silyl acetals react with (94) to give aminoesters (97) in the presence of triflic acid (Scheme... 

A -Methyleneamine equivalents can be generated from 1,3,5-trisubstituted hexahydro-1,3,5-triazines in the presence of a Lewis acid (LA) and used for aminomethylation reactions with various nucleophiles at the -position of amines (Scheme 16). A -Methyleneaniline equivalents, as shown by 110 and 111, result from the breaking of all three carbon-nitrogen bonds of l,3,5-triphenylhexahydro-l,3,5-triazine 109. They have characteristics of imine and iminium ions similar to Mannich bases and can be used for various aminomethylation reactions. However, there have been no reports of using A -methyleneamine equivalents as azadienes, which may react with olefins via [47t-F2Jt] cycloaddition to afford 1,2,3,4-tetrahydroquinolines 112 <2000T5259>. 

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