Organic Syntheses, CV 6, 815
Checked by Robert A. Clement and Richard E. Benson.
1. Procedure
A slurry comprised of
33.6 g. (0.0998 mole) of commercial phenylmercury(II) acetate,
200 ml. of acetonitrile, and
14.4 g. (16.8 ml., 0.200 mole) of methallyl alcohol (Note
1) is prepared in a
500-ml., three-necked flask fitted with a
mechanical stirrer, a
condenser, and a
thermometer. The slurry is stirred and cooled in an
ice bath, and
22.4 g. (0.0998 mole) of powdered palladium(II) acetate (Note
2) is added over 1 minute. Stirring is continued with cooling for 1 hour, then at room temperature for 3 more hours (Note
3). The temperature of the reaction mixture reaches a maximum of 27° after removal of the ice bath.
The black reaction mixture is diluted with about
100 ml. of diethyl ether and poured onto
200 g. of ether-wet alumina (Woelm, Activity Grade 1) in a
45 × 2.5 cm. glass chromatographic column. The product is washed through the
alumina with about
1 l. of ether. The brown eluate is concentrated by distilling the
ether through a
45-cm. Vigreux column on a
steam bath at atmospheric pressure. When the
ether has been distilled, a slight vacuum is applied, removing most of the
acetonitrile. After the volume reaches about 50 ml., the mixture is filtered into a
100-ml. distillation flask, removing some precipitated
palladium metal. The flask is rinsed with
10-ml. of ether, and the rinse is combined with the product. The flask is equipped with a
10 cm. Vigreux column for distillation at reduced pressure. After removal of the solvent,
8.1–8.5 g. (
55–58%) of
2-methyl-3-phenylpropionaldehyde is collected, b.p.
75–85° (3 mm.) (Note
4),
n25D 1.5113 (Note
5).
2. Notes
3. The yield improves slightly with stirring overnight; the checkers obtained the aldehyde in
69% yield in this manner.
4. The bulk of the product has b.p.
77–80° (3 mm.).
5. The product is 90–95% pure by GC and NMR analyses. The checkers estimated the purity to be at least 95% by these criteria. The
1H NMR spectrum (CDCl
3) shows peaks at δ 0.95 (d,
J = 6.5 Hz., 3H),

2.7 (complex m, 3H), 7.20 (s, 5H) and 9.65 (d,
J = 1.5 Hz., 1H).
3. Discussion
The formation of 3-aryl-substituted aldehydes and 3-aryl-substituted ketones by the reaction of "arylpalladium salts" with allylic alcohols is general.
2 Illustrations of the preparation of two aldehydes and two ketones are given in Table I.
TABLE I
3-ARYLCARBONYL COMPOUNDS FROM ALLYLIC ALCOHOLS AND “PHENYLPALLADIUM ACETATE”2
|
Allylic Alcohol |
Product |
Yield, % |
Boiling Point, °C. |
|
CH2=CHCH2OH |
C6H5CH2CH2CHO |
35 |
220–225°a |
trans-CH3CH=CHCH2OH |
C6H5CH(CH3)CH2CHO |
36 |
67–75° (1 mm.) |
trans-CH3CH=CHCH(OH)CH3 |
C6H5CH(CH3)CH2COCH3 |
51 |
70–75° (3 mm.) |
(CH3)2C=CHCH(OH)CH3 |
C6H5C(CH3)2CH2COCH3 |
29 |
83–87° (2 mm.) |
|
a Purification by careful distillation is necessary in this example to remove cinnamaldehyde which is also formed in the reaction (b.p. 252°).
|
The presence of nitro, carboalkoxy, carboxyl, chloro, formyl, alkyl, and acyl groups does not interfere with the reaction. A single alkoxy group also does not interfere, but if two or more are present the yields are markedly decreased. The reaction is inhibited by the presence of unhindered, basic nitrogen substituents, by the phenolic group, and probably by the thiol group.
This preparation is referenced from:
10
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