CHEM 4D03
Hello, dear friend, you can consult us at any time if you have any questions, add WeChat: daixieit
CHEM 4D03
Question 1. A) In your own words (3-4 sentences), define what is meant by both “plateau” and “pinnacle” reactions as discussed in class. Use diagrams, provide a good example of each and discuss these in relation to the overall planning of a synthetic strategy (15).
B) Define what is meant by “linear” and “convergent” synthetic plans and outline the merits of convergence in an overall synthesis (15).
Question 2. (30) Provide the missing reagent (starting material, reagent or product) necessary to
complete the following FIFTEEN reactions below. Indicate stereochemistry where appropriate. Standard work-up conditions and solvents can be assumed. Place your response in the box provided.
|
(f) |
O |
Bu4NF
THF
H
O
|
|
|
|
CO2Et
HO
CO H
PhCH2 H
H OH
O
PhCH2 
H
MeO I
|
(j) |
O
O |
O
O |
OMe
Pd(PPh3)4
O O
(k) H C 
Ph
|
1) LDA, -78 C |
|
2) PhCHO |
(l)
|
O |
NRR |
Cl2Ru=CHPh(PCy3)
|
o CH2Cl2 , 40 C |
O OMOM
(m) 
OTBS
Pd(PPh3)4 , C6H6
|
Ph-B(OH)2 |
(n)
O
|
|
|
|
|
2) Trap with PhCH2Br |
O O
(o) + H
H
O OH
|
99% e.e. |
Question 3. ASYMMETRIC SYNTHESIS (25): Many methods are available for the preparation of chiral molecules in organic synthesis. Discuss what is meant by each of the following techniques providing a clear example, highlighting the origin of asymmetry in each case (5x5). Do not use specific examples described elsewhere on this examination paper.
Substrate control. Reagent control. Auxiliary control. Chiral pool. Organocatalysis.
Question 4. APPLIED SYNTHESIS (15): Propose an asymmetric synthesis of any three (3x5) ofthe following four compounds from achiral precursors. You may use any chiral pool agent, chiral
ligand/catalysts or auxiliary that may be required.
|
|
|
|
|
2022-02-24