Chemistry - Converting a cis-alkene to trans-alkene

Solution 1:

Your method looks fine. There is another simple method (with three steps though).

1. Convert the the cis alkene to a dibromo derivative using bromine;
2. Use two equivalents of $\ce{NaNH2}$ to get an alkyne (elimination);
3. Selective reduction to trans alkene by using sodium in liquid ammonia.
   However this requires that Hydrogen be present as a substituent on the double bond, on both carbons.

Solution 2:

For E/Z trisubstituted alkenes capable of E₂ elimination the following sequence may apply. Add the elements of water in a syn, anti-Markovnikov fashion to the double bond. Remove the elements of water as p-toluenesulfonic acid via anti E₂ elimination. The cycle below illustrates this point.