View Policies Current Attempt in Progress There are 20 common, naturally occurring amino acids from which all proteins are derived (as will be discussed in Chapter 25), although many other less common amino acids have been isolated from natural sources. Valine is one of the 20 common amino acids, and it was used as a starting material in the laboratory synthesis of an uncommon amino acid (Tetrahedron 1997, 53, 1151-1156). During one of the steps in the synthesis, compound 1 was treated with HBr under conditions that favor radical addition, giving stereoisomers 2 and 3. Draw the structures of 2 and 3, and describe their stereoisomeric relationship. OCH HBT hy + 3 H (S)-valine Modify the given copies of compound 1 to drawthe structures of 2 and 3. You can use the single bond tool to add/remove double bonds. CH CH HC- HC . CH Edit Drawing