Transacylation reactions methods

Levy, M.C., Edwards-Levy, F. (1996). Coating alginate beads with cross-linked biopolymers a novel method based on a transacylation reaction. Journal of Microencapsulation, 13, 169-183. 

The preparation of imidazolides by acylation of imidazole with acid chlorides is sometimes limited by the inaccessibility or instability of the required acid chlorides (e.g., formyl chloride, highly unsaturated acid chlorides, etc.) or by side-reactions in the case of multifunctional systems. For these reasons and due to the availability of an easy and convenient procedure involving very mild conditions, imidazolides today are usually prepared directly from the corresponding carboxylic acids with jV -carbonyldiimida-zole (CDI) or one of its analoga (see page 16). Use of these reagents has become more and more the preferred method for activation of carboxylic acids to azolides and their further transacylation to esters, amides, peptides, etc. (see subsequent Chapters). 

In animal and plant tissues this pathway is of much less importance than the one using CDP-choline - in mammals only the liver uses this method to any extent (20-40% of the total phosphatidylcholine synthesized) - but it is the method used in those bacteria which contain phosphatidylcholine. The other three pathways generally have low activity but may be important in special circumstances. For example, the acylation of monoacylphos-phatidylcholine is used for the incorporation of specific fatty acids into phosphatidylcholine and may be the main method by which arachidonic acid is acylated at the sn-2 position (section 3.4.9). The transacylation (method 5) reaction takes place between two molecules of 1-monoacyl-phosphatidylcholine and, because saturated fatty acids are esterified at... 

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