2- alkanoate ester Transformation

Analogously, alkanoic esters 15 were transformed via alkylsilyl ketene acetals 16 and their chloromethylcarbene adducts 17 (not isolated) into 2-methylalk-2-enoic esters 18 (EjZ mixtures). 

More conveniently, 2-(methylthio)alkanoic esters are prepared from 2-acetylalkanoates (eq 2)] MeSSMe cannot replace MeSS02Me as the sulfenylating agent in this transformation. Advantages of these methods over others such as sulfenylation of an alkanoic acid and its ester or alkylation of (methylthio)acetic acid are (1) simplicity of the procedure (2) efficiency and convenience of using inexpensive base (EtONa) and EtOH as solvent with high product yields and (3) no bissulfenylation. Moreover, the latter... 

A stimulating development of urea alcoholysis has been demonstrated very recently for better AE, in an innovative integrated process that incorporates fatty ester hydrolysis to co-amino-alkanoic acids [44], Within the scope of this chapter, the most interesting step of this process is the recycling of waste alcohol, formed by the hydrolysis step, for urea alcoholysis. Dialkyl carbonate is produced together with ammonia thereafter, the ammonia is engaged in the amination reaction to obtain the amino acids. The overall process avoids the storage of NH3 that is necessary for the amination route, and transforms a waste product-the alcohol-into the valuable dialkyl carbonate. 

In the case of the double NPS-protected lysine methyl ester, oxidation selectively takes place at the 6-sulfenamide function under spontaneous cyclization via the a-sulphe-namido group as nucleophile. Only one diastereoisomer of the A,A -bis(NPS)-protected methyl 6-amino-piperidine-2-yl-carboxylate seems to be formed. The transformation of a-amino alkanoates and diaryl or dialkyl disulfides to the aryl- or alkylsulfenimine derivatives can be performed electrochemically using MgBr2 as a mediator system. This reaction can either proceed in one step or starting from the corresponding sulfenamide [170]. 

In Summary Esters are named as alkyl alkanoates. Many of them have pleasant odors and are present in nature. They are less reactive than acyl halides or carboxylic anhydrides and therefore often require the presence of acid or base to transform. With water, esters hydrolyze to the corresponding carboxylic acids or carboxylates with alcohols, they undergo transesteriflcation and, with amines at elevated temperatures, furnish amides. 

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