read the organic letters paper from 2009 entitled origin of thermodynamic versus kinetic control of allene hydroboration with 9 borabicyclo 3 3 1 nonane and 10 r trimethylsilyl 9 borabicyclo 3 3 2 decane and answer the following questions

Read and answer the following questions?

  • Summarize, in your own words, what the Ess and Roush Groups studied in this paper.
  • In a hydroboration reaction, which product (E or Z) is expected to form?
  • Why is this product expected?
  • Draw the two possible products that can form (Scheme 1).
  • Give the reference for the paper where it was shown that (Z)-crotyl-10-TMS-9-borabicyclo[3.3.2]decanes are more thermodynamically stable.
  • Give the specific reaction being studied.
  • What led the group to study allene hydroboration?
  • How are they studying this reaction (i.e. what methods are they using)?
  • Which product, Z-3 or E-3, requires less energy to form?
  • Give one reason this product is observed.
  • What is the structure of 9-BBN?
  • What does the phrase “Z-E hydroboration selectivity” mean?
  • Describe the TS that converts Z-3 into E-3.
  • What does it mean to be “kinetically favored”?
  • What causes the increase in barrier for the rearrangement of Z-7?
  • In Scheme 4a, what is the most thermodynamically stable product Z-5 or E-5?
  • In Scheme 4a, what is the most thermodynamically stable product Z-7 or E-7?
  • In Scheme 4a, which is the kinetically favored product, Z-5 or E-5?
  • In Scheme 4a, which is the kinetically favored product, Z-7 or E-7?
  • Label the energy profile below for the reaction of 1a and 2b.
  • What causes the large barriers for TS-Z9 and TS-E9?
  • Does the Si atom of the TMS group affect the barrier of TS-Z7?
  • If yes, how does it affect the barrier. If no, why does it not affect the barrier?
  • How many boat/chair conformations of the borabicyclo auxiliary exist?

What do the authors conclude the cause of kinetic control to be?