Naming, acid anhydrides alkenes

These reactions occur at about 100°C using aluminum chloride as a catalyst. This accepts a lone pair of electrons from the halogen atom on the haloalkane or acyl halide, which results in a positive charge on the adjoining carbon atom. The reaction is then ELECTROPHILIC SUBSTITUTION. It is also possible to use alkenes (for alkylation) and acid anhydrides (for acylation). It is named for the French chemist Charles Friedel (1832-99) and the US chemist James Crafts (1832-99). 

Such perfect cases of equilibration are rare. Another important one concerns equilibration by Michael addition to conjugated alkenes. A classic case is the preparation of maleate 47 and fumarate 48 esters from (the necessarily Z-) maleic anhydride 46. Simple treatment with methanol in acidic solution gives the liquid maleate 47 as expected. It is unusual for cis and trans alkenes to be given different names maleic and fumaric acids were named before their relationship was understood. 

Another amino acid synthesis is called the azlactone synthesis. Remember from before that an azlactone is an oxazolone (see 95). When glycine (52) is converted to its AT-benzoyl derivative (112 known as hippuric acid) by reaction with benzoyl chloride, treatment with acetic anhydride (AC2O) gives the azlactone 113. This is the reaction presented in the preceding section (see compormd 95). Compound 110 has the common name of hippuric acid azlactone. As with the thiohydantoin, the -CH2- unit in 113 is susceptible to an enolate anion condensation reaction with aldehydes (Chapter 22, Section 22.7.2), and reaction with 2-methylpropanal in the presence of pyridine gives azlactone 114. Catalytic hydrogenation of the alkene unit (Chapter 19, Section 19.3.2) and acid hydrolysis lead to the amino acid leucine (55). 

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