Author:
Florio Saverio,Capriati Vito,Lame Joana,Read Jacquelyne A.
Abstract
Abstract
image
(X = Br)
[
1730‐25‐2
]
C
3
H
5
BrMg
(MW 145.29)
InChI =
1S/C3H5.BrH.Mg/c1‐3‐2;;/h3H,1‐2H2;1H;/q;;+1/p‐1
InChIKey =
FEMBXICCJNZMMC‐UHFFFAOYSA‐M
(X = Cl)
[
2622‐05‐1
]
C
3
H
5
ClMg
(MW 100.84)
InChI =
1S/C3H5.ClH.Mg/c1‐3‐2;;/h3H,1‐2H2;1H;/q;;+1/p‐1
InChIKey =
PLYLAFITHJUEGX‐UHFFFAOYSA‐M
(allylating agents capable of easy addition to carbonyl compounds,
15–23
nitro compounds
57
and nitriles,
58–61
imines
43–50
and aza aromatics,
51–56
unactivated alkenes,
30–42
and of displacement reactions on halo compounds
6,24–28,53,54
)
Physical Data:
Br: fp −40 °C;
d
0.851 g cm
−3
(commercial reagent). Cl: fp −17 °C;
d
0.995 g cm
−3
(commercial reagent).
Solubility:
Br: very sol ether. Cl: slightly sol ether; sol THF.
Form Supplied in:
Br: 1.0 M solution in Et
2
O packaged under N
2
. Cl: 2.0 M solution in THF packaged under N
2
.
Preparative Methods:
allylmagnesium bromide and chloride can be easily prepared by direct reaction of
Magnesium
with
Allyl Bromide
and
Allyl Chloride
, respectively
2–5
in diethyl ether and/or tetrahydrofuran. An excess of Mg (preferably 10%) is recommended.
6,7
Prior amalgamation of
very pure
Mg
3,4
suppresses the formation of 1,5‐hexadiene. An improved preparation
8
uses a THF slurry of Mg, obtained by co‐condensation in a rotating solution reactor.
9
Preactivation of Mg by dry stirring in an inert atmosphere is also highly beneficial.
10
Allylpotassium can be readily converted into the magnesium analogs by simply adding a solution of
Magnesium Bromide
in THF.
11,12
Most of the work on allylic Grignards has been carried out with the bromide. Indeed, the bromide can be prepared in slightly higher yield than the chloride and shows a greater solubility in ether.
1
Handling, Storage, and Precautions:
both moisture‐sensitive; highly inflammable; react violently with water; induce burns. Bottles of these reagents should be flushed with N
2
, kept tightly sealed to preclude contact with oxygen, and stored far from sparks. In case of contact with eyes and skin, wash immediately with abundant water.