Ring-transformation equilibrium with participation of π-bonded S in an isothiazole system. Synthesis of non-ring-transformed 5-(2-aminovinyl) isothiazole derivative via …
Abstract Substituents at 5-position of 5-amino-3-methyl-and 3-p-chlorophenyl-5- methylisothiazoles (7 and 8) were silylated and then lithiated to couple with aromatic nitriles in order to afford the adducts (4 and 5) via 1, 3-silyl group shift. Desilylation of 5 with TBAF gave solely non-ring-transformed product (3-α-form). By using the pure sample of 3-α-form, the reversible ring-trans-formation (bond switch) was observed Full-size image (< 1 K)