[plankk]

I have had a task to choose a molecules, which are optically active. According to the answer molecule (in attachment) has sterocenter and it is optically active. As far as I know the all subtituents should be different, and in that example we have two the same - methyl - susbtituents. So how could it be optically active?

[azmanam]

you're right, it's not.  In general, tetrasubstitued amines can be optically active if a) all four substituents are different and b) the amine cannot invert easily (i.e. the 4th substituent is usually not a proton)

[plankk]

Thanks a lot.