Author Topic: (MeO-subst.)benzyl bromide --> allylbenzene  (Read 1929 times)

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(MeO-subst.)benzyl bromide --> allylbenzene
« on: June 10, 2002, 12:07:00 PM »
this rnx uses a methoxy & isopropyl ring-substituted benzyl bromide :
   (3-Methoxy-4-Isopropyl)benzyl bromide

5-Allyl-2-isopropyl-1-methoxybenzene (73)

To a cold (-40°C) solution of cuprous iodide (1.35g, 7.06mmol)
suspended in ether (30mL) was added 70.6mL of vinylmagnesium
bromide (71.0mmol, 1M solution in THF). After the solution was
stirred for 15min, 11.45g of benzyl bromide(72) (4.71mmol) in
40mL of ether was added. The reaction mixture was maintained at
-40°C for 1h, then warmed up to -25°C, and stirred for a period
of 10h. Standard ethereal workup, followed by chromatography
(elution with hexanes), gave 8.44g of adduct(73) (95%) as a
slightly yellow liquid which was homogeneous by TLC analysis
[hexanes, Rf(73)=0.40]

benzyl bromide(72) = (3-Methoxy-4-Isopropyl)benzyl bromide

j org chem, 1997 62(20): 6928-6951
"Use of Conjugated Dienones in Cyclialkylations:
Total Syntheses of Arucadiol, 1,2-Didehydromiltirone,
(±)-Hinokione, (±)-Nimbidiol, Sageone, and Miltirone"
George Majetich, Shuang Liu, Jing Fang,
David Siesel, Yong Zhang