dataframe sample data until I have N different values in 1 column

I need to sample data until I have N different values in 1 column

for example:

df = pd.DataFrame([1,1,1,2,3,2,3,2,3,1,4,5,3,4,5,2,3,2], columns=['col'])

a possible result for N=3 can be:

[1,1,1,2,1,2,3,1,2,3]

or:

[1,2,4,1,2,4,2,1,1,1,1]