The compound 5-chlorohex-3-en-2-ol, CH3-CH(OH)-CH=CH-CH(Cl)-CH3, is available as the (2R,3E,5S) isomer. How many of its stereoisomers are diastereomers of this isomer?

JEE Advanced levelSingle correct optionDifficulty 3 of 3st043

The compound 5-chlorohex-3-en-2-ol, $CH X_{3} - CH (OH) - CH = CH - CH (Cl) - CH X_{3}$ , is available as the $(2 R, 3 E, 5 S)$ isomer. How many of its stereoisomers are diastereomers of this isomer?

The molecule has two stereocentres (C2, C5) and one stereogenic double bond with no symmetry, giving

2^{3} = 8

stereoisomers. Exclude the isomer itself and its enantiomer

(2 S, 3 E, 5 R)

, the only mirror image. All remaining

8 - 2 = 6

differ in at least one but not all stereogenic units, so they are diastereomers.