Answer to Question #8325 in Organic Chemistry for Meenaakshi

Question

How many possible stereoisomers for threonine ? Thereoretically,if we use the formula 2^n,since there is 2 chiral carbon for a threonine,the stereoisomers must be 4.However,according to several resources, there is one pair of diastereomers for threonine. Now I'm confused whether the actual stereoisomers are 3 or 4.
Need help and explanation asap. Thank you

Answer 1

Threonine exists in four possible stereoisomers with the following
configurations: (2S,3R), (2R,3S), (2S,3S) and (2R,3R).