How many stereoisomers does 1, 3-dibromocyclopentane have?

[299678]

I know how to calculate # of stereoisomers by using 2^n, n = # of chiral centers, but

How many chiral centers for 1,3 dibromocyclopentane? text book said it has 2 chiral center, but chiral center should have 4 different substituents?

I knew this stuff,but suddenly got confused

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[UCB05]

I know how to calculate # of stereoisomers by using 2^n, n = # of chiral centers, but

How many chiral centers for 1,3 dibromocyclopentane? text book said it has 2 chiral center, but chiral center should have 4 different substituents?

I knew this stuff,but suddenly got confused

C1 and C3 are both chiral centers.
C1 has the following substituents: -H, -Br, -CH2CHBrCH2CH2-, -CH2CH2CHBrCH2-
Notice the two carbon chain substituents are not the same, therefore C1 is chiral. C3 also has the same substituents and therefore chiral as well.

There would be 3 stereoisomers. 1S,3S; 1R,3R; 1S,3R/1R,3S(same molecule)

 

[299678]

Great ! thanks

 

[RCT PC CRN]

Can someone explain possible number of streoisomers based on number of streocenter (chiral center)? Obviously 2^n doesnt work in the example here. 2^2=4 and we got 3 streoisomers. 2 streoisomers are identical.

In multpile choies question, we are not going to have time to draw all possible streoisomers and to see whether there are identical streoisomers !!!

I'm trying to see if someone knows some specific rules.

 

[TexasOMFS]

Can someone explain possible number of streoisomers based on number of streocenter (chiral center)? Obviously 2^n doesnt work in the example here. 2^2=4 and we got 3 streoisomers. 2 streoisomers are identical.

In multpile choies question, we are not going to have time to draw all possible streoisomers and to see whether there are identical streoisomers !!!

I'm trying to see if someone knows some specific rules.

2^n only gives the maximum possible stereoisomers, no specific rules but always just look for internal lines of symmetry as these can indicate meso compounds. You'll have plenty of time to draw it out, I finished the science section with 25 mins left.

 

[PreparationIsKey]

C1 and C3 are both chiral centers.
C1 has the following substituents: -H, -Br, -CH2CHBrCH2CH2-, -CH2CH2CHBrCH2-
Notice the two carbon chain substituents are not the same, therefore C1 is chiral. C3 also has the same substituents and therefore chiral as well.

There would be 3 stereoisomers. 1S,3S; 1R,3R; 1S,3R/1R,3S(same molecule)

The meso would be the cis form right?