Alkenes to 4,5-Dihydro-l,3-oxazoles

Benzenetellurinyl trifluoroacetate converts olefins in the presence of acetonitrile, propionit-rile, or benzonitrile, in a reaction catalyzed by boron trifluoride-diethyl etherate to 2-acylamino-1-ethyl phenyl tellurium oxides. The mixture was then heated at 75° for 3 h to elfect elimination of the phenyltelluro group and cyclization to the dihydrooxazole.  

Takahashi, S. Uemura. N. Sugita, Kenkyu Hokoku-Asahi Garasu Kogyo Gijutsu Shore Kai 50, 101 (1987) C.A. 109, 128350 (1988). 

Irgolic Organo Tellurium Compounds with 2 Te—C Bonds or 1 Tc=C Bond 

When these reactions were carried out in 1,2-dichloroethane as reaction medium and Wethoxycarbonylcyanamide instead of acetonitrile, 4,5-dihydrooxazoles with the ethoxy-carbonylamido group in the 2-position were isolated.  

The following 2-ethoxycarbonylamido-4,5-dihydrooxazoles were prepared in this manner  

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