`1,2`-Dimethylcyclopentene in heated with `H_(2)NNH_(2)` (hydrazine) and an oxidant `(H_(2)O_(2)`. The product is

Options

A. exclusively cis-`1,2`-dimethylcyclopentane
B. exclusively trams-`1,2`-dimethylcyclopentane
C. an equimolar mixtue of (1) and (2)
D. an unequal mixture of (1) and (2)

Answer

A

Explanation

The other product is `N_(2)`. Hydrazine, `H_(2)NNH_(2)`, is oxidized to the unstable `Hoverset(..)N=overset(..)NH` (diimide), "that donates its" `H's` "to" `C=C` "in a concerted fashion through a six-membered" `TS`. The mode of addition is syn.