Bond‐switch rearrangement of 3‐oxo‐Δ4‐1,2,4‐thiadiazolin‐5‐yl ureas

Abstract 5‐Amino‐3‐oxo‐Δ 4 ‐1,2,4‐thiadiazolines 5a,b react with isocyanates to yield 1,2,4‐thiadiazolidine derivatives 9a‐d via bond switching of the corresponding isomers 7 . The same type of products 9e‐m was obtained by treatment of 5‐amino‐1,2,3,4‐thiatriazoles 6a‐d with two equivalents of isocyanate.