Schiff bases reactions with acid chlorides

The key intermediate 21 is in principle accessible in any of several ways. Thus reaction of thiophenecarbox-aldehyde with amninoacetal would lead to the Schiff base treatment with acid would result in formation of the fused thiophene-pyridine ring (21). Alkylation of that intermediate with benzyl chloride gives the corresponding ternary iminium salt. Treatment with sodium borohydride leads to reduction of the quinolinium ring and thus formation of ticlopidine (24). ... 

Many examples of the usual route to /S-lactams via imines and acid chlorides, ketens, or keten equivalents have appeared.These include syntheses of 3-[bis(alkylthio)methylenamino]-2-azetidinones, ° of spiro-azetidinones and bis-azetidinones, and the use of l-methyl-2-halogenopyridinium salts to activate carboxylic acids towards coupling with imines. A non-hazardous alternative route to 3-amido-2-azetidinones, avoiding the use of azidoacetyl chloride, involves the reaction of Schiff bases with salts of [(a-methyl-/3-methoxycar-bonyl)vinylamino]acetic acid, e.g. (20), in the presence of ethyl chloroformate, as shown in Scheme 5. Formaldimines can be generated from their trimers by treatment with Lewis acids immediately prior to reaction with acid chlorides, so allowing the formation of the nocardicin nucleus which is unsubstituted at C-4. ... 

The acylation of enamines derived from cyclic ketones, which can lead to the acyl ketone or ring expansion (692-694), was studied by NMR and mass spectroscopic analysis of the products (695,696). In a comparative study of the rates of diphenylketene addition to olefins, a pronounced activation was observed in enamines (697). Enamine N- and C-acylation products were obtained from reactions of Schiff s bases (698), vinylogous urethanes (699), cyanamides (699), amides (670,700), and 2-benzylidene-3-methylbenzothiazoline (672) with acid chlorides, anhydrides, and dithio-esters (699). 

Reaction of Schiff bases 422 with a mixture of phosphorus oxychloride and dichloroacetic acid in DMF gave triazolopyrimidinones (423) instead of the expected 3,3-dichloroazetidinones (424) (88JHC173). 1,4-Cycloaddition of 422 (R = SMe R1 = Ph) with phenoxyacetyl chloride in the presence of triethylamine gave the dihydro-1,2,4-triazolo[4,3-ajpyrimidinone 425 (88JHC173) (Scheme 82). 

Figure 14-1 Functionalization and activation of electrode materials, a) silanization of supports bearing hydroxylic groups b) reaction with cyanuric chloride c) activation with cyanogen bromide d) binding via amide bonds after activation with 1,1-carbonyldiimidazole e) activation with good leaving groups such as tresyl chloride f) formation of Schiff bases between aldehyde groups on the support and amino groups at the biomolecule g) activation of carboxylic groups with carbodiimides or h) via the acid chlorides.

Bose has described reactions between acid chlorides ISl and Schiff bases 152 in which the stereoselectivity depends on the order of addition of the reagents (Scheme 5.42) [86]. When the condensation was conducted by a normal addition sequence (i.e. acid chloride last), only the cis /i-lactam 153a was formed. If, however, the inverse addition technique (triethylamine last) was used, 30% cis 153a and 70% trans 153b yS-lactams were obtained under the same conditions. When the reaction was conducted in a microwave oven with chlorobenzene as the solvent, the ratio of trans 153b to cis 153a yS-lactams was 90 10, irrespective of the order of addition, and isomerization to the thermodynamically more stable trans j8-lactam 153b did not occur. 

Bose et al. [77] compared a similar reaction of the acid chloride of tetrachlor-ophthaloyl glycine 57 with a Schiff base under MW irradiation and conventional... 

As noted earlier, most classical antidepressant agents consist of propylamine derivatives of tricyclic aromatic compounds. The antidepressant molecule tametraline is thus notable in that it is built on a bicyclic nucleus that directly carries the amine substituent. Reaction of 4-phenyl-l-tetralone (18) (obtainable by Friedel-Crafts cyclization of 4,4-diphenyl butyric acid) with methyl amine in the presence of titanium chloride gives the corresponding Schiff base. Reduction by means of sodium borohydride affords the secondary amine as a mixture of cis (21) and trans (20) isomers. The latter is separated to afford the more active antidepressant of the pair, tametraline (20). 

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