Trifluoroacetamides , to protect

Protected primary allylic amines were generated from allylic carbonates and ammonia equivalents. Iridium-catalyzed allylic substitution has now been reported with sulfonamides [90, 91], imides [89, 91-93], and trifluoroacetamide [89] to form branched, protected, primary allylic amines (Table 5). When tested, yields and selectivities were highest from reactions catalyzed by complexes derived from L2. Reactions of potassium trifluoroacetamide and lithium di-tert-butyhminodi-carboxylate were conducted with catalysts derived from the simplified ligand L7. Reactions of nosylamide and trifluoroacetamide form singly-protected amine products. The other ammonia equivalents lead to the formation of doubly protected allylic amine products, but one protecting group can be removed selectively, except when the product is derived from phthalimide. 

Because of the strong electron-withdrawing effect of the trifluoromethyl group, trifluoroacetamides are subject to hydrolysis under mild conditions. This has permitted trifluoroacetyl groups to be used as amino-protecting groups in some situations. 

Monoalkylation of support-bound amines can also be realized by a three-step protocol involving initial protection/activation of the amine (e.g. as 2-nitrobenzenesulfon-amide [132,133], trifluoroacetamide [102], or 4,4 -dimethoxybenzhydrylamine [66]) followed by N-alkylation and deprotection. In particular, if monomethylations (see, e.g., Entry 7, Table 10.7) or allylations are to be performed, this three-step strategy will generally give the best results. 

Fluonnated organosihcon compounds are very useful for introduction of tnalkylsilyl protecting groups in synthesis TVialkylsilyl trifluoroacetamides are perhaps the best known of these agents, for they can be used to prepare stlyl ethers orsdyl esters [91, 92] (equation 76)... 

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