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

E

M+

Chapter 15

11.2Prep of Organometallic Compounds

Grignard (organomagnesium compound)

H3CCH2

Br + Mgo ether H3CCH2

Mg-Br

H3CC Mg Br

HH

δ(-) δ(-)δ(+)H3CCH2

Br

:Mg

ether

free radical like H3CC Mg Br

HH

covalent

and

ionic view

11.3

H3CCH2

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 Compounds

Grignard

11.4

How 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

+

O

HC

CC

C

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 O

C

CH3

CH3

H

BrMg+ -O

CCH3

CH3

H+

++C

C

H

H

IMg CH2CH3

δ+ δ-C

C

H

CH2CH3H

MgI

H3C C

H3C

H3C

Li + H NH

H

H3C 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 Reagents

Prep 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

H2C

R H3CH2CC

R(CH3CH2)2CuLi

δ- δ+ H H+

IH2C

RCCHH

HH

H

CCHH H

H

H

Cu+Li+

11.10Use: Substitution, replace leaving group

I

R

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+

OCH3

H+/H2O(neut.)

11.11

LiO

H

HD

THF 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−

O2. 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

O

CN?

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

O

CN

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

OH

CNO

C:N+

RCO3H

1. DMSO2. H2O

PCC

O

CN

SM

target

O

Br

OH

Br

11.21

synthesissynthesis

O

O

OH

How?“thoughts”--- join---

OH

O

X

CH3X

+

11.22

synthesissynthesis

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

O

RCO3H PBr3 Mg/THF

H+/H2O

11.24

OH

OH

Br

+ olefin

H2O

Br2/Δ

+ other Brs

H2

cat

olefinsOH +H2SO4

Δ

O

HBr

Mgo

etherH+

H2O

OH

HBrH2O2

PCC