摘要:1) The structure of the unknown substances (Substances I, II, and III) described in Part XXXVIII were determined as 6-chloro-2-methylthiopyridyl-3-urea, 6-ethoxy-2-methylthiopyridyl-3-urea, and 6-ethoxy-2-ethylthiopyridyl-3-urea, respectively. 2) Mechanism of cleavage of the 2-aminothiazo1o [5, 4-b]pyridines was studied.