Question Question/Help about isomers in synthesis

[madmaximus]

How you synthesis cis/trans end product ,what is the physical thing that i need to do , for example - you used only cis precursors to get a final product with cis+ isomer ?

 

[Osmosis Vanderwaal]

There's a few tactics. Yes to using chiral reactants but also sn2 reactions sometimes attack from the back and invert the handedness. In this way, a person could get for instance D- methamphetamine from D(1s,2s) pseudoephedrine or L(1r,2r) pseudoephedrine. Enantio-selective synthesis or enantiomeric asymmetric synthesis. There's a couple other procedures used also. I'm not a chemist, just a chemistry enthusiast.