page 20
The acetylation reaction in dichloromethane produced alfa and beta in a 97:3 ratio.
A 500-ml, 3-necked, round-bottomed flask was equipped with a
Teflon paddle stirrer, a gas vent tube and an addition funnel which
had been modified so the added solution would drop directly into the
solution rather than down the side of the flask. The apparatus was
cooled in ice water, and a methylene chloride (100 ml) suspension of
aluminum chloride (75 g) in the flask was continuously stirred while
acetyl chloride (40.5 g) was added over a period of 5 minutes. The
addition funnel was rinsed with 10 ml of CH2cl2.
A solution of naphthalene (34 g) in CH2c12 (100 ml) was added over
a period of 15 minutes, during which the reaction mixture changed from
opaque white to yellow. The temperature was increased to 27°C, and the
mixture was stirred for 30 minutes, the color deepening to orange. The reaction mixture was worked up to yield GK-IV in 93% yield.
(!!! my note - the amount of naphthalene seems to be a mistake and should be doubled) |