Synthesis of cyclic N-hydroxylated ureas and oxazolidinone oximes enabled by chemoselective iodine(III)-mediated radical or cationic cyclizations of unsaturated N-alkoxyureas

Laure Peilleron , Pascal Retailleau (1) , Kevin Cariou (1)

1 ICSN - Institut de Chimie des Substances Naturelles

In this study we describe the reactivity of unsaturated N-alkoxyureas in the presence of different combinations of a hypervalent iodine(III) reagent and a bromide source or TEMPO. Three complementary cyclizations can be achieved depending on the reaction conditions. On the one hand, PIFA with pyridinium bromide leads to an oxybromination reaction. On the other hand, bis(tert-butylcarbonyloxy)iodobenzene with tetrabutylammo-nium bromide or TEMPO triggers aminobromination or aminooxyamination reactions, respectively. Control experiments showed that the three reactions proceed through distinct mechanisms: the first process is ionic while the other two follow a radical manifold.

Mots clés: Hypervalent iodine; bromination; cyclization; radicals; TEMPO

Domaines: Chimie organique

Laure Peilleron, Pascal Retailleau, Kevin Cariou. Synthesis of cyclic N-hydroxylated ureas and oxazolidinone oximes enabled by chemoselective iodine(III)-mediated radical or cationic cyclizations of unsaturated N-alkoxyureas. Advanced Synthesis and Catalysis, 2019, 361 (22), pp.5160-5169. ⟨10.1002/adsc.201901135⟩. ⟨hal-02403999⟩