Synthesis of Three-, Five-, and Six-Membered Heterocycles Derived from New β-Amino-α-trifluoromethyl Alcohols

Nucleophilic trifluoromethylation of α-iminoketones 2, derived from arylglyoxal, with Ruppert-Prakash reagent (CF3SiMe3) offers a convenient access to the corresponding O-silylated β-imino-α-trifluoromethyl alcohols. In a ‘one-pot’ procedure, by treatment with NaBH4, these products smoothly undergo reduction and desilylation yielding the expected β-amino-α-trifluoromethyl alcohols 4. The latter were used as convenient starting materials for the synthesis of diverse trifluoromethylated heterocycles, including aziridines 5, 1,3-oxazolidines 8, 1,3-oxazolidin-2-ones 9, 1,3,2-oxazaphospholidine 2-oxides 10, 1,2,3-oxathiazolidine 2-oxides 11, and morpholine-2,3-diones 12. An optically active 5-trifluoromethyl-substituted 1,3-oxazolidin-2-one 9g was also obtained