Synthesis of Macrocycles by a Passerini Reaction

SCHEME 8.9 General reaction to give access to a-(phosphinyloxy)amides 28. 

While the first two macromolecules 34 and 35 are obtained under very mild reaction conditions, heating of the multicomponent mixture was necessary for the last two products 36 and 37, where alcohols were employed instead of unstable aldehydes, which are in situ oxidized with IBX (as described in Section 8.3). The use of the more easily accessible alcohols in the last approach under oxidative conditions increases the possibilities of this reaction giving easy access to difficult frameworks, which would not be available otherwise because of the lack of stability of the aldehydes employed. 

EIGURE 8.2 Depsipeptide-like macrocycles synthesized through a multicomponent P-3CR. 

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