FGIs

4,153 views
3,913 views

Published on

Published in: Technology, Business
0 Comments
2 Likes
Statistics
Notes
  • Be the first to comment

No Downloads
Views
Total views
4,153
On SlideShare
0
From Embeds
0
Number of Embeds
6
Actions
Shares
0
Downloads
234
Comments
0
Likes
2
Embeds 0
No embeds

No notes for slide

FGIs

  1. 1. RETROSYNTHETIC APPROCH TO ORGANIC SYNTHESIS FUNCTIONAL GROUP INTERCONVERSION Dr. Shaikh S. Nizami Department of Chemistry University of Karachi
  2. 2. FUNCTIONAL GROUPS INTERCONVERSIONS
  3. 3. CONTENTS <ul><li>Definition of Functional Group Interconversion (FGIs) </li></ul><ul><li>Importance of FGIs </li></ul><ul><li>Functional group containing heteroatoms </li></ul><ul><li>Unsaturated hydrocarbons </li></ul><ul><li>Removal of Functional Groups </li></ul>
  4. 4. Definition of F unctional G roup I nterconversion <ul><li>The process of writing one functional group for another to help synthetic planning is known as FGI </li></ul>
  5. 5. Definition of F unctional G roup I nterconversion <ul><li>FGI can be done by </li></ul><ul><li>Substitution </li></ul><ul><li>Addition </li></ul><ul><li>Elimination </li></ul><ul><li>Oxidation </li></ul><ul><li>Reduction </li></ul>
  6. 6. Why FGI is needed? <ul><li>A TM containing more than one functional group, one functional group may interfere with desired reaction on second functional group during a synthesis. </li></ul>
  7. 7. Why FGI is needed? <ul><li>This problem can be solved into ways </li></ul><ul><li>a) Use of protecting group </li></ul><ul><li>b) Change in synthetic strategy (using FGI) </li></ul>
  8. 8. Importance of FGIs <ul><li>It helps in identifying suitable disconnection. </li></ul><ul><li>Consider the synthesis of ketone containing a double bond. </li></ul><ul><li>Alkenes may be prepared by the dehydration of alcohol. </li></ul>
  9. 9. Importance of FGIs TM First step in the retrosynthetic analysis of TM could be functional group interconversion to an alcohol But which alcohol ?
  10. 10. Importance of FGIs FGI i FGI ii TM
  11. 11. RETROSYNTESIS FGI + TM Matched Latent Polarity (Consonant) i
  12. 12. RETROSYNTESIS FGI ii Mismatched Latent Polarity (Dissonant)
  13. 13. Functional group containing heteroatoms <ul><li>For convenience these functional groups will be initially divided into three major classes depending upon their oxidation level </li></ul>
  14. 14. a) Carboxylic acid and their derivatives <ul><li>Compounds in this class are the highest oxidation level of organic compounds </li></ul><ul><li>It includes </li></ul><ul><li>Carboxylic acid (RCO 2 H) </li></ul><ul><li>Esters/lactone (RCOO 2 R) </li></ul><ul><li>Amide/lactam (RCONHR) </li></ul><ul><li>They may be interconverted by a series of simple reactions </li></ul>
  15. 15. Transformations of carboxylic acid derivatives SOCl 2 or PCl 5 H 2 O NH 3 RO - H 2 O H 2 O H + / R’OH H 2 O
  16. 16. b) Aldehydes, ketones and their derivatives <ul><li>Functional groups in this class are at lower oxidation level than class (a) </li></ul><ul><li>It includes the features C=X in which the carbon atom is bonded directly to either hydrogen or carbon. </li></ul>
  17. 17. b) Aldehydes, ketones and their derivatives <ul><li>The group includes </li></ul><ul><li>Aldehydes (RHC=O) </li></ul><ul><li>Ketones (RR’C=O) </li></ul><ul><li>Imines (RR’C=NR”) </li></ul><ul><li>Hydrazones (RR’C=NNHR”) </li></ul><ul><li>Oximes (RR’C=NOH) </li></ul>
  18. 18. Transformations of aldehydes aldehyde R’NH 2 R’=alkyl, aryl,(imine) R’=NMe2 (hydrazones) R’=OH (oxime) H 2 O HS(CH 2 ) 3 SH/H+ 2R’OH/H +
  19. 19. c) Alcohols and their derivatives <ul><li>Apart from Alcohols (ROH) themselves, this class includes </li></ul><ul><li>Amines (RNH2) </li></ul><ul><li>Thiols (RSH) </li></ul><ul><li>Disulphides (RSSR) </li></ul><ul><li>Ethers (ROR) </li></ul><ul><li>Alkyl halides (RX) </li></ul>
  20. 20. Interconversions of alcohols and halides SOCl2 or PCl5 HO - HBr HO -
  21. 21. Use of a sulphonic ester as a leaving group R’SO 2 Cl Nu - + R’SO 3 -
  22. 22. Interconversions between the three oxidation levels a,b & c above <ul><li>To move between groups classified in the previous section, it is necessary to perform a reduction or oxidation at some stage. </li></ul>
  23. 23. Oxidation <ul><li>Many methods have been developed for the oxidation of organic compounds. </li></ul><ul><li>It is possible to transform a low oxidation level FG into any group of higher level. </li></ul>
  24. 24. Oxidation Primary alcohol PCC or PDC CrO 3 /H + Secondary alcohol PCC or PDC PCC= pyridinium chlorochromate PDC= pyridinium dichromate
  25. 25. Reduction Esters LiAlH 4 + R’OH Amides LiAlH 4 Nitriles LiAlH 4 1 eq. DIBAL-H Low temp.
  26. 26. Unsaturated Hydrocarbons H 2 ,Pd/C OsO 4 O 3 HBr RCO 3 H BH 3 ,NaOH/ H2O 2
  27. 27. Removal of Functional Group Alcohol to corresponding hydrocarbon Alcohol Dehydration Alkene Alkane Hydrogenation
  28. 28. Removal of Functional Group Clemmensen Wolf-Kishner Zn,HCl NH 2 NH 2 ,KOH Aldehydes/ ketones to hydrocarbons

×