Basic Concepts Of Retrosynthesis (Part 2)
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Transcript of Basic Concepts Of Retrosynthesis (Part 2)
RETROSYNTHETIC APPROCH APPROCH
TOTOORGANIC SYNTHESISORGANIC SYNTHESIS
Dr. Shaikh S. NizamiDr. Shaikh S. NizamiDepartment of ChemistryDepartment of Chemistry
University of KarachiUniversity of Karachi
BASIC BASIC CONCEPTS
(Part 2)
CONTENTS
Examples of Retrosynthetic Examples of Retrosynthetic analysis of:analysis of:
1-Phenylhexanol (TM 1.1)1-Phenylhexanol (TM 1.1)
RETROSYNTHETIC ANALYSISRETROSYNTHETIC ANALYSIS 1-PHENYLHEXANOL1-PHENYLHEXANOL
Ph CH3
OH
Ph CH3
OFGI
(TM 1.1)(TM 1.1)
11stst RETROSYNTHETIC ANALYSISRETROSYNTHETIC ANALYSIS
1-PHENYLHEXANOL1-PHENYLHEXANOL
TM
Path 1
+
+ CH3
?
CH3Br
---------------------------------------------------------------------
Path 2
OH
Ph+
CH3-
+Ph H
O
CH3
BrMg
Ph CH3
OH
-
OH
Ph
SYNTHESISSYNTHESIS
CH3Br Mg
Et2OCH3
BrMg
Ph H
O
CH3Ph
OMgBrH+/H2O
TM
22ndnd RETROSYNTHETIC RETROSYNTHETIC ANALYSISANALYSIS
1-PHENYLHEXANOL1-PHENYLHEXANOL
Ph CH3
OH
TM
---------------------------------------------------------------------
Path 1
Path 2
Ph+
+
-
OH
CH3
?
Ph-
+
+CH3
OH
PhMgBr
PhBr
CH3H
O
SYNTHESISSYNTHESIS
PhBr + Mg Et2O PhMgBr
PhMgBr +CH3H
OH
+/H2O TM
33rdrd RETROSYNTHETIC RETROSYNTHETIC ANALYSISANALYSIS
1-PHENYLHEXANOL1-PHENYLHEXANOL
OH
Ph CH3
Ph
OH
+
+
CH3
-
O
Ph
BrMg CH3
TM
SYNTHESISSYNTHESIS
O
Ph+
BrMg CH3
Ph CH3
OMgBrH
+/H2O
TM
44thth RETROSYNTHETIC ANALYSIRETROSYNTHETIC ANALYSI 1-PHENYLHEXANOL1-PHENYLHEXANOL
Ph CH3
OH
TM
FGI
Ph CH3
O
Ph CH3
O-Ph
O
+
+CH3
Ph CH3
O
Br CH3
SYNTHESISSYNTHESIS
Ph CH3
O i) -OEt
ii)Br CH3 Ph CH3
O
LiAlH4
TM
55thth RETROSYNTHETIC ANALYSISRETROSYNTHETIC ANALYSIS 1-PHENYLHEXANOL1-PHENYLHEXANOL
Ph CH3
O
+Ph
O
+- CH3
Ph
O
LiCu2)(
CH3
SYNTHESISSYNTHESIS
Ph
O
+ CH3( )
2LiCu
Ph CH3
O
TMNaBH4
66thth RETROSYNTHETIC ANALYSISRETROSYNTHETIC ANALYSIS 1-PHENYLHEXANOL1-PHENYLHEXANOL
Ph CH3
O
+Ph
O
+
-CH3
Ph
O
LiCu(CH3)2
SYNTHESISSYNTHESIS
Ph
O
+
LiCu(CH3)2
Ph CH3
O
MeOH
/CuINaBH4 TM
What is the best What is the best synthesissynthesis??
Availability of the reagentAvailability of the reagentSynthetic step should be kept Synthetic step should be kept
minimum unless there is an minimum unless there is an advantage of FGIadvantage of FGI
Disconnection of C-C bond Disconnection of C-C bond should be in the center of a should be in the center of a moleculemolecule
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