11.1
OrganometallicOrganometallic CompoundsCompounds (R-M)(R-M)Organomagnesium & Organolithium compds 15.1
Lithium Diorganocopper (Gilman) Reagents 15.2
Not covered: Organopalladium reagents, Heck reaction, carbenes, carbenoids, & alkene metathesis.
Synthesis, Concepts and the Final
HC
CC
C
H H
H H
H H
H
HM
E
HC
CC
C
H H
H H
H H
H
H
EM+
Chapter 15
11.2Prep of Organometallic CompoundsGrignard (organomagnesium compound)
H3CCH2
Br + Mgo ether H3CCH2
Mg-Br
H3CC Mg BrH H
δ(-) δ(-)δ(+)H3C CH2
Br
:Mg
ether
free radical like H3CC Mg BrH H
covalent
and
ionic view
11.3
H3C CH2
Br + Mgo ether H3CCH2
Mg-Br
Alkyllithium
H3C CH2CH2-Br + 2Lioether
H3C CH2 CH2-Li + LiBr
H3C CH2 C
H
H
Li
OR
Prep of Organometallic CompoundsGrignard
11.4How does one make the anion of butane?
HC
CC
C
H H
H H
H H
H
H
HC
CC
C
H H
H H
H H
H
H HC
CC
C
H H
H H
H H
H
H
Br+ Lio Li
HC
CC
C
H H
H H
H H
H
H
Li
+
OH
CC
CC
H H
H H
H H
H
H
Li+
OHH
Use - base(E2) or Nu: (SN2)
11.5B. Rxs - protic compounds (acids - chapter 4)
H3Cδ- δ+
+ H3C HMgBr
H OC
CH3
CH3
H
BrMg+ -OC
CH3
CH3
H+
++C
C
H
H
IMg CH2CH3δ+ δ-
CC
H
CH2CH3H
MgI
H3C CH3C
H3CLi + H N
H
HH3C C
H3C
H3C
H + NH
H
δ- δ+Li+
11.6
Prep of R-M (Nu:- +M)alkyl halide (sp3) + metal
e.g. Grignard or organomagnesium reagent
But also: vinyl halide (sp2) + metalaryl halide (sp2) + metal
MgXether Mgo
(meta l)
X+
δ+
δ−
δ−
11.7Lithium Diorganocopper ReagentsPrep and use in Synthesis
(similar Grignard reagent can be made)
RLi + CuI + LiI'ether' R2CuLi
'ether'+2 CH3CH2Li + CuI (CH3CH2)2CuLi LiI
'ether'+2 CH3MgI + CuI (CH3)2CuMgI MgI2
11.8Use: substitution rx, replace halides
Or as anion
Organometallics, alkyllithiums can be nucleophiles…..Chapter 7 and 9
C Li etherBrδ+δ-+ H+/H2O
(neut.)CH
solventCCH
+ Li Br
C:etherBr+
H+/H2O(neut.)CH solvent
Li CCH+ Li Br
11.9Use: substitution rx, replace halides
but cuprates are better
Grignards and alkyllithiums can be nucleophiles…..
H3C Li THFOS
O
O
R H3Cδ+δ-+ H+/H2O
(neut.)
'ether'+I
H2CR H3CH2C
CR
(CH3CH2)2CuLiδ- δ+ H H
+I
H2CR
CCHH H
H
H
CCHH H
H
H
Cu+Li+
11.10Use: Substitution, replace leaving group
IR
R'R
R'
CuMgBr+2
'ether' H+/H2O(neut.)
addeliminate*
ICuLiether
2 + H+/H2O(neut.)
addeliminate*
*not really SN2, ignore mechanism, 2nd semester
Br OCH3LiCu
2 ether+
OCH3H+/H2O
(neut.)
11.11
LiOH
HDTHF H+/ H2O
(neut.)+δ- δ+ OH
H
HD
Primary site inverted, secondary unchanged.
Rxs substitution in chapter 11
11.12Organometallic Compounds 15
earlier = RMgX or RLi
Li O
HO1. ether+ 2. H+/H2O
(neut)
Better
2. H+/H2O (neut)
O
CuMgX
HO1. ether
+
2
11.13
Nucleophilic RxsMgX
1. etherO+
δ+
δ−2. H+/H2O (neut.)
OH
MgX
1. etherO
+ δ+
δ−
O
2. H+/H2O (neut.)
OH
11.14
R O
H
δ+δ-
Nu:
R O
HNu etc.
R O
HNu
H+
H2O(neut)
R O
HNu H
R O
H
δ+δ-
Nu:
O
H
δ+
MgBrδ+ δ-
δ-
O
H
H+
H2O(neut)
O
H
H
O
:CH3Li
O
CH3
H+
H2O(neut)
O
CH3
H
11.15Nucleophilic Rxs - important for 2nd semester carbonyl addition
MgX
1. etherO
+ δ+
δ−
O 2. H+/H2O (neut.)
OH
1. etherHO
+ MgHXδ+
δ−
O 2. H+/H2O (neut.)
OH
same product different connection
11.16
N
H
X
N
H H
+
SM target
NBS hv
Br DMF
N H
H
N
H
+
11.17
SYNTHESIS
SM target
OC
N?
Propose how to convert starting material (sm) to a target
rules: Use any number of stepsFor each step show:
- necessary reagents- necessary conditions - expected product or products
11.18
SYNTHESIS
OC
N
starting material
target
Compare functional groups and carbon skeleton
Need: 1 carbon (CN) and ketone + nitrile from olefin
11.19
SYNTHESIS retroanalysis
OC:N
Br
+
OH
Br
Br2
H2OxsO
CN
SM
target
NC-/DMFPCC
11.20
SYNTHESIS retroanalysis
Br2
H2OxsPCC
NC-/DMF
OHC
NO
C:N +
RCO3H
1. DMSO2. H2O
PCC
OC
NSM
target
O
Br
OH
Br
11.21synthesissynthesis
O
O
OH
How?“thoughts”--- join---
OH
O
X
CH3X +
11.22synthesissynthesis
plan
O
O
OH
How?synthesissynthesis
O
O
OH
How?
OH
O
X
CH3X +
NaH
O-
H
+Na
polaraprotic X
O
-NH2
or R:-
H3C-I
O
HgSO4H2O
O
Oexpectedbyproduct
+
O
H
reverse?
11.23
OH
OH
Br
O
OH
ORCO3H PBr3 Mg/THF
H+/H2O
11.24
OH
OH
Br
+ olefin
H2O
Br2/Δ
+ other Brs
H2cat
olefinsOH +H2SO4
Δ
O
HBr
Mgo
etherH+
H2O
OH
HBrH2O2
PCC
