Chemistry Reference
In-Depth Information
O
O
X
reagents
O
O
9
4
3
9
4
4
X = Br; NaOH
X = OAc; R
3
N, Pd(0) catalyst
34%
94%
Scheme 9.14
Ar
2
CHNH
2
(Ph
3
P)
4
Pd
Ar
OAc
Ar =
p
-MeOC
6
H
4
H
Ar
9
.
5
9
.
6
Scheme 9.15
CO
2
Me
(Ph
3
P)
4
Pd
CO
2
Me
+
OAc
CO
2
Me
CO
2
Me
9
4
9
4
Scheme 9.16
OH
OTBS
H
NaH, Me
3
SnCl
Pd(OAc)
2
, Ph
3
P
OTBS
O
H
OBz
9.49
9.50
Scheme 9.17
Pd(dba)
2
,
DMF, LiCl
+
Me
3
Sn
OMe
OMe
OAc
9.51
Scheme 9.18
Main-group organometallics can also be allylated in this way, provided that they are not so reactive that
they attack the acetate carbonyl group. Organotin compounds are suitable (Scheme 9.18).
26
Mechanistically,
the reaction is slightly different as the “nucleophile” does not transfer to the allyl group directly, but via
the palladium. This is similar to the Stille coupling (Section 2.5). The stereochemical consequence of this
is discussed below (Section 8.1.3). Allyl halides may also be coupled with allyl stannanes (Scheme 9.19).
Regioisomeric mixtures result, unless one end of the allyl system is distinctly more hindered.
27
Zinc
28
and
silicon
29
reagents have also been employed (Scheme 9.20).
