Handbook of Functionalized Organometallics Applications in S

O
O
+
+
R
R
E
E
NiCl 2(PPh 3) 2
Zn, ZnCl2,Et3N 68% (combined yield, 8:92)
E E H H E E
10.7 Reactions of Enones with Alkynes
O O
NiCl 2(PPh 3) 2
ZnCl 2,Zn,Et 3N
41%
R=Me,E=CO2Me The enynone product from the above reaction can further react with an organozinc
or borane reagent in the presence of Ni(COD) 2 and occasionally a phosphine
ligand to produce diastereoselectively the corresponding bicyclononene derivatives
in good yield. When Et 3SiH is employed,a similar product with an addition of a
hydridic moiety is observed [168].
O
H
H
H
O
H
H
H
+
Bu3Sn Ph
C 6H 13
Ph
Et 3B
Ni(COD) 2/PBu3 85%
Ni(acac) 2
DIBALH
Me3SiCl 74%
O
H
Ph
H
HO
H
H H
E
E
+
Ph
C 6H 13
E
E
H
Et
H
3SiH
Ni(COD) 2
PPh3 86% (>97:3 dr)
H
H H
O
Et 3SiO
Oxygen- and nitrogen-tethered alkynyl enones give the corresponding heterocycle
with stereoselective exocyclic olefins [169].
Me
Me
O
O
O
O Ph
N
H
H
ZnMe 2
Ni(COD) 2
58%
ZnMe 2
Ni(COD) 2
70%
Me
Me
O Me
The reaction has been extended to the synthesis of (+)-a-allokainic acid and provided
a new entry to the isogeissoschizoid skeleton [170±173].
O
O
N
O
Me
Ph
H
H
H
H
425
E
E
E E
H
Ph