Organic Reactions Volume 4 - Sciencemadness Dot Org

THE SYNTHESIS OF BENZOINS 299
C6HBCOCOCOC6H5 -> C6H5C(OH)COC6H5 -> C6H5CHOHCOC6H5
1
CO2H
2-Methoxymandelonitrile and resorcinol react in the presence of zinc
chloride in hydrochloric acid (Hoesch reaction) to give a ketimine
hydrochloride, which can be hydrolyzed to 2'-methoxy-2;4~dihydroxybenzoin.
149 Benzoylmandelonitrile reacts similarly with resorcinol to
form a non-crystalline phenolic substance, which on acetylation gives
2,4-diacetoxy-O-acetylbenzoin. 150
2-CH3OC6H4CH(OH)CN + C6H4(OH)2 -> 2-CH3OC6H4CHOHCC6H3(OH)2 -»
NH-HCl
2-CH3OC6H4CHOHCOC6H3(OH)2-2,4
C6H5CHCN + C6H4(OH)2 ~> 2,4-(CH3C02)2C6H3COCHC6H5
OCOC6H5
OCOCH3
Phenylmagnesium bromide reacts with carbon monoxide under pressure
151 or with nickel carbonyl 152 to give benzoin in 70% yield.
TABLE OF BENZOINS PREPARED BY VARIOUS METHODS
In Table II are listed the benzoins whose preparation has been described
up to November, 1947. The numbers in the column headed
"Method' 7 refer to the following methods of preparation: (1) benzoin
condensation; (2) from isomeric benzoin; (3) condensation of an arylglyoxal
with an aromatic hydrocarbon; (4) the Grignard reaction; (5) reduction
of benzils; (6) reduction of aromatic acids or their derivatives;
(7) from desoxybenzoins.
149 Ishidate, J. Pharm. Soc. Japan, 542, 311 (1927) [C. A., 22, 1153 '(1928)].
150 Baker, /. Chem. Soc, 1930, 1015.
151 Benton, Voss, and McCusker, J. Am. Chem. Soc, 67, 82 (1945).
152 Fischer and Staffers, Ann., 500, 253 (1933).