Abstract
The Baylis-Hillman adducts 1 were treated with a large amount of CCl3 CN in the presence of DBU without solvent to give in good yield the corresponding trichloroacetimidates 5 which by thermal [3.3]sigmatropic rearrangement were converted into the corresponding (E )-2-trichloroacetylaminomethyl-2-propenoates 6 , exclusively. On the contrary, when compounds 5 were treated with a catalytic amount of DABCO in dichloromethane, 2-methylene-3-trichloroacetylamino esters 7 were obtained in good yield. Both 5a and 7a underwent iodocyclization, to give a cyclic intermediate precursor of a polyfunctionalized sequence, and the differences in stereoselectivity were in agreement with computational results.
Key words
amino acids - amides - rearrangement - cyclization - stereoselectivity
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