ca01 only detailed ToC 1..24

1.1.1 Nickel Complexes of 1,3-Dienes 33
Scheme 3 Preparation of a (ç 4 -Buta-1,3-diene)nickel(0) Complex [15]
Ni(cdt)
+
P P
Pri Pri Pri Pri +
Et 2O
−78 o C
85%
Pri P
P
Ni Pri Pri Pri Pri [ì-(1,2,3,9-ç:6,7,8,10-ç)-3,6-Dimethyleneocta-1,7-diene]bis[ethane-1,2-diylbis(diisopropylphosphine-k
2 P)]nickel (4): [15]
3,6-Dimethyleneocta-1,7-diene (0.56 mL, 3.30 mmol) and iPr 2P(CH 2) 2P-iPr 2 (1.03 mL,
3.30 mmol) were added to a suspension of Ni(cdt) (0.83 g, 3.31 mmol) in Et 2O (200 mL)
cooled to –788C. The mixture was allowed to warm to rt over 5 h. A yellow solid precipitated
which then redissolved to give a red soln. The mixture was stirred for 2 d, filtered
through a pad of Avicel, and evaporated to dryness. The residue was dissolved in toluene
(50 mL) at 508C and filtered. Cooling the filtrate to –788C gave compound 4 as red needles
which were washed with precooled pentane (10 mL) at –788C and dried under high vacuum;
yield: 1.09 g (85%).
Applications of Product Subclass 1 in Organic Synthesis
1.1.1.2 Method 2:
Diene–Diene Cycloadditions
The most widely used application of nickel–diene complexes is the dimerization of 1,3dienes.
Pioneering studies by Wilke demonstrated many different modes of coupling, including
dimerization, trimerization, and oligomerization of 1,3-dienes. [5,7] An overview of
the product classes that may be obtained from 1,3-dienes is provided in Scheme 4 (see also
Houben–Weyl, Vol. E 18, pp 93 and 932–937). The initially formed nickel complexes 5 and
6 have not been isolated. However, the complexes may be stabilized by the addition of
phosphines, and ð-allyl complexes 7–9 have been prepared and characterized.
Scheme 4 Products of Nickel-Catalyzed Butadiene Dimerization and Trimerization [5,7]
L nNi
[Ni(0)] L nNi L nNi
5
Ni
9
7
L nNi
L nNi
8
6
Pr i
4
Ni
P
P
Pr i
Pr i
for references see p 79