The Diels-Alder Reaction

M

CN

200 C,

CN

O

12%

NC

CN

O

NC

CN

NC

CN

O

Rfx, 100 %

205 C,

H

H

NC

CN

O O

O

low yield

23

R

Ni(COD)2 /PPh3

+

+

DCM

R

R

exo

endo

M

MeO2C

MeO2C

CO2Me

CO2Me

R Ni(COD)2/PPh3

CO

Me

+

+

80 C, DCM

2

+

+

R

R

R

R

ortho

para

meta

meta'

Ni(COD)2

R

2 PPh3

+

L

Ni

L

Ni

L

Ni

L

23

L = COD

R

R

R

R

M

E

E

E

E

E

+

THF

E = CO2Me

! "

− 78 C

E

4 h

17%

E

E

E

H

E

H

E

O

O

O

80 C

O

O

! "

+

H

O

H

E

E = CO2Me

E

E

OSMT

OSMT

OSMT

∆

! "

Ph

CCl4

Ph

Ph

O

O

O

O

O

O

O

19 kbar

200 C

+O

95%

−CO2

O! "

O O

O

87%

O

O

O

M

LUMO

ED

ED

EW

EW

EW

+

HOMO

EW = electron-withdrawing

ED

ED = electron-donating

normal

LUMO

LUMO

2

1

HOMO

2

1

HOMO

Me

Me

M

LUMO

LUMO*

HOMO*

HOMO

Ph

H

! "

H hν

Ph

H

Ph

24

25

H

O

H

H

H

H

O

H

H

hν

H

O

! "

O

O H

O

O

H

27

26

M