(二) Predict the major product  and offer a mechanistic explanation Hint: addition, SN2, cyclization, and then elimination.

二、非選擇題 (一)For the following DBr addition reaction (D; deuterium), a cyclohexyl halide product (X) was obtained. Use "curved arrow" to show the details of the reaction mechanism of the formation of this product (X). Need to include the formation of intermediate(s) in your answer.