Challenge Problem 08.95 When the given 2-butyl compounds are treated with t-BuOK
ID: 538387 • Letter: C
Question
Challenge Problem 08.95 When the given 2-butyl compounds are treated with t-BuOK in t-BuOH at 50 °C, the major product is generally 1-butene (as expected with a sterically hindered base), while the minor products are cis-2-butene and trans-2 butene. In cases where the leaving group is a halogen (I, Br, or Cl), the trans-alkene is favored over the cis-alkene. However, the cis-isomer becomes the favored 2-alkene when the leaving group is a tosylate group (J. Am. Chem. Soc. 1965, 87, 5517-5518) 6) Y transcis 1.4 1.3 OTs 06 Bt In cases where the leaving group is a halogen (I, Br, or CI), the trans-alkene is favored over the cis-alkene. Which of the following transition state argument is correct in this regard? Formation of both cis- and trans-isomer occurs via a transition state that lacks this steric interaction. O Formation of the cis-isomer occurs via a transition state that exhibits a gauche interaction, while formation of the trans-isomer occurs via a transition state that lacks this steric interaction. O F via a transition state that exhibits a gauche interaction, while formation of the cis-isomer occurs via a transition state that lacks this steric interaction. Formation of the trans-isomer occurs O Formation of both cis- and trans-isomer occurs via a transition state exhibits a gauche interaction.Explanation / Answer
1 FORMATION OF CIS AND TRANSE ISOMER WILL OCCURS VIA A TRANSITION STATE EXIHIBITS A GAUCHE INTERACTION
2 THE TRANSITION STATE IN TRANSE ISOMER LACKS GAUCHE INTERACTION