Iodine Iodoacetamide

Many approaches to y-lactams have been dependent on cyclization by acyl-nitrogen bond formation [22]. Cyclization involving carbon-carbon bond formation is an alternative route however, until recently, this potential methodology has received little attention. Mori and co-workers reported a palladium-catalyzed cyclization of A -allyl iodoacetamides, in which the intramolecular addition reaction of the carbon-iodine bond to an olefinic linkage is a key step [23]. 

Rosner (124) oxidized the liberated iodide with hydrogen peroxide and then estimated the iodine formed colorimetrically (see also (101)). Smythe (129) allowed the reaction to proceed in a bicarbonate-COi buffer system and followed the evdution of COi manometrically. Iodoacetate has been used to block the effect of —SH groups in polarographic titrations (32,125). For results obtiuned with iodoacetate and iodoacetamide see (10,17,106, 119,120). 

The PEGylation reactions with 38 are usually performed using an excess of the reagent in a darkened flask, in order to Emit the formation of iodine, which can react with other amino acids. mPEG-iodoacetamide is a commercially available reagent that can be prepared by the reaction of mPEG-amine 42 with iodoacetic anhydride in diox-ane [178]. Examples of the use of 38 include the PEGylation of acyl-coenzyme A and cholesterol acyltransferase [198]. 

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