Question

How many diastereomers can `H_3C-CH=CH-CH(OH)CH_3` generate?

Answer 1

For `H_3C-CH=CH-CH(OH)-CH_3`, I count 4 diastereomers........

Explanation:

You gots `H_3C-CH=CH-CH(OH)-CH_3`, with 2 sites of dissymmetry, (i) the olefinic bond, which can of course be cis or trans depending on the geometry to methyl or alcoholic groups, and of course the asymmetric carbon,

`H_3C-CH=CH-stackrel(*)CH(OH)-CH_3`.

The alcoholic carbon is bound to 4 different substituents. And thus it should generate a pair of enantiomers. This simple molecule can thus generate 4 diastereomers.