The nitration of ethyl 2 bromomethylthiazole 4 carboxylate (Ⅱ) with NaNO 2 or AgNO 2 gave ethyl 2 nitromethyl 4 carboxylate (Ⅲ). It was found that Ⅲ existed in the aci nitro tautomer in DMSO d 6

and the nitro isomer of Ⅲ was nearly the only form in CDCl 3. Under the Michael reaction condition

Ⅲ condensed with acrylamide to give the 1

3 dipolar addition product

ethyl 2 [3′(5′ amidodihydroisoxazolyl)]thiazole 4 carboxylate (Ⅴ)

and not the Michael addition product.