Esters condensations, potassium tert-butoxide

The aniline nitrogen is then converted to the para-toluenesulfonamide (4-3). Reaction of this intermediate with ethyl co-chlorobutyrate in the presence of potassium carbonate then gives the alkylation product (4-4). Potassium tert-butoxide-catalyzed Claisen condensation of this diester leads to azepinone (4-5) as a mixture of methyl and ethyl esters resulting from alternate cyclization routes. A strong acid leads to the transient keto-acid, which then decarboxylates the toluensulfonyl group is lost under reaction conditions as well as affording the benzazepinone (4-6). This last intermediate is then acylated with the benzoyl chloride (4-7) to afford amide (4-8). 

This reaction involves the condensation of an aldehyde or ketone with an a-halo ester in the presence of a basic condensing agent (sodium ethoxide, sodamide, finely divided sodium or potassium tert.-butoxide) to give a glycidio (or ap-epoxy) ester. Thus acetophenone and ethyl chloroacetate yield phenyl-methylglycidic ester (I) ... 

The condensation of aldehydes and ketones with succinic esters in the presence of sodium ethoxide is known as the Stobbe condensation. The reaction with sodium ethoxide is comparatively slow and a little reduction of the ketonic compound to the carbinol usually occurs a shorter reaction time and a better yield is generally obtained with the more powerful condensing agent potassium ieri.-butoxide or with sodium hydride. Thus benzophenone condenses with diethyl sucoinate in the presence of potassium tert.-butoxide to give a 94 per cent, yield of (3-carbethoxy-YY-diphenylvinylacetic acid (I) is the potassium salt ... 

The condensation of dimethyl diglycolate and aryl glyoxylates in the presence of potassium tert-butoxide as base provided a series of 4-arylfuran-3-ols bearing one tert-butyl ester and one methyl ester. As such, this furandicarboxylate allowed an easy differentiation of the two esters for selective chemical modifications <01TL6429>. 

Homer-Emmons condensation consists of substituted phosphonate ester reacted with terephthaldehyde in presence of potassium tert-butoxide to produce alternating copolymer. Fig. 12 [45]. 

---