Mannich derivative

Due to environmental concerns, research efforts have been directed toward the replacement of chromate-based post-treatments. This paper focuses on a new unique chromium free post-treatment based on "Mannich derivatives" of po1y-viny1pheno 1 which have demonstrated excellent performance on both zinc and iron phosphate treatments. 

The quality observed with "Mannich" derivatives of polyvinylphenol is affected by the concentration, time of treatment, temperature, pH, and whether or not a final deionized water rinse is used. The results shown in Tables I-III below represent evaluations conducted for poly-[methy1(2-hydroxyethy1)amino]methyl-4-vinylphenol, as shown in Structure I. Post-treatments based on polyvinylphenols overcome deficiencies observed with previous chrome-free rinses, since these systems are reactive and a final water rinse actually improves performance as is illustrated in Table I where the new non-chrome system is evaluated on Bonderite 1000, an iron phosphate conversion coating, as a function of concentration with and without a final water rinse. It is also... 

On zinc phosphate conversion coatings, the "Mannich" derivatives of poly-4-vinylphenol have demonstrated performance equivalent to chromic chromate systems in salt spray, humidity, and physical testing. In addition. Table III illustrates results observed with automotive body paint systems evaluated by the "scab" or "cycle" test which causes failure more typical of actual end use conditions than do salt spray evaluations. Again, results equivalent to chromic-chromate post-treatments were obtained. In addition, the humidity resistance and adhesion tests were essentially equivalent to the chromium controls. 

Use of trimethylsilyl triflate to bring about Piunmeier rearrangement requires the presence of a base such as a tertiary amine (vide supra equations 15 and 26). In some instances, involving attempts to alkylate Pummerer intermediates with silyl enol ethers under such conditions, the base has been found to compete as a nucleophile. In the absence of the silyl enol ether, amine addition can be very efficient. For example, treatment of methallyl phenyl sulfoxide with diisopropylethylamine and trimethylsilyl inflate in dichloromethane (equation 29) at 0 C yields the ammonium triflate indicated in 91% yield. Other tertiary amines which undergo this reaction include niethylamine and Af,Af-diethyltrimethylsiI-amine. In the latter case with allyl phenyl sulfoxide as the substrate and a mildly acidic wotk-up, the Mannich derivative shown in equation (30) can be obtained in 90% yield. ... 

Some of the Mannich derivatives reported in Fig. 49 are relevant in alkaloid chemistry. In particular, obtaining the tctrahydroisoquinoline ring 144 is a fundamental step in the synthesis of protoberberines (Chap. IV, A). 

Deaminomethylation of Mannich bases (path a in Fig. 81), which is actually a retro-Mannich reaction, as it reproduces the same reactants employed in the direct synthesis, has been observed in practically every class of Mannich derivative (Table 22 and Figs. 186, 189 in Chap. V). C-Mannich bases are more stable than the corresponding derivatives, having the aminomethyl group linked to a heteroatom. This has been directly found, for example, in barbituric acid derivatives, although the C-Mannich bases deriving from particularly activated subsU atcs, such as nitroalkanes, also exhibit a remarkable tendency to decompose. "... 

J. E., Mannich derivatives of medicinal.s. II. Derivatives of some carbonic anhydrasc inhibitors, / Med Chem.. 14, 458, 1971. 

C-Mannich derivatives of uridine 467 and thymidine s or N-Mannich bases of cy-tidinc iododcrivatives arc yielded from nucleosides subjected to aminomethyla-(X = 0. NAIkyl) iof, presence of the glycoside moiety may favor the reaction at C-5 (arrow in 468) through the formation of a polycyclic structure bearing an electron-attracting group inserted at the adjacent position, C-6. ... 

In addition to crosslinked resins, insoluble ion exchangers may also be obtained with good results by suitable functionalization of fibers based on cellulose" ° or other materials. In this connection, product 541 is 541 a notable example of a Mannich derivative of the pro-pargylic ether of cellulose." ... 

This formulation is laid down by electrophoresis over the material to be coated, acting as the cathode, and finally heat cured. The process requires molecules with chemical structure suitably designed for different applications, and the chemistry of Mannich bases may represent a convenient tool for preparing variously substituted derivatives. In fact, as depicted in Fig. 187, the reactive functions leading to the final crosslinked material may be bound to several different positions of the oligomeric epoxy resin. The Mannich derivatives of bisphenol A (572)2 " - > -2 and nonylphenol (573)202.2a i.2()6 con-... 

Fig. 4. General classification of Mannich derivatives according to substrate and amine type.

Kig. 5. Synthesis of a Mannich derivative from a phosphorous ester. 

ITic thermodynamic stability of the ring to be formed also plays a very important role in this group of Mannich derivatives, as formaldehyde in some cases may enter in the final cyclic product in the dimeric form, thus yielding the oxa-aza-heterocyclic structures of type C. 

Heterocyclic compounds originated by the involvement of the amine moiety of the base (group B) can be prepared from several different classes of Mannich derivatives P-aminoketones in particular, are largely employed. Thus, 4-hydroxypipcridines 322 are obtained from bis-ketones 321 (Fig. 124), prepared by Mannich synthesis with primary alkylaminc. Both the mechanism and the stereochemistry - of the reaction have been investigated it has been demonstrated that cyclization proceeds -stereo.specif-ically, and the resulting product has the configuration depicted in 322. 

In contrast to the compounds described above, Mannich derivatives employed as auxiliaries arc used in relatively low amounts as curing agents in the crosslinking of polymeric products or as modifiers to improve the final performances of macromolecular... 

Two routes were originally developed for the synthesis of intermediate diketone 18 ( R= butyl).One involved introduction of the two carbonyl groups by oxidation of the corresponding dibutyl heptacyclic terpyridine. The other route is similar to that shown in Fig. 2, except that 14 was prepared by pyrolysis of the trimethylhydrazonium derivative of 12. An improved method for this 1/3+1/3 coupling reaction involves condensing the HCl salt of Mannich derivative 13 with ketone 12 and ammonium acetate, giving heptacyclic terpyridyl 14 in 70% yield. The synthesis of 9-butyloctahydroacridine (9) and its conversion to N-oxide... 

Some fluoroquinolones appear to be active against fni and parasites. For instance, the Mannich derivatives of norfloxacin 132 demonstrate a considerable antifungal activity against Histoplasma capsulatum. One of compounds of this family is more active than clotrimazole towards Microsporum audouinii, while other derivatives surpass clotrimazole in relation to Cryptococcus neoformans or Microsporum gypsum. From all derivatives 132 which have been studied (Scheme 57), compound with R=Br, X=N, R =NH2, Y-Z=CH, A=COMe, R -R3=OMe proved to exhibit the highest antifungal activity (MIC for Cryptococcus neoformans and Microsporum audouinii 0,6 pg/ml) [341],... 

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