I got the article - if someone's interested, i can mail it to him.
A dry, argon flushed, 500 mL round-bottom flask, equipped with a
magnetic stirring bar and a 200 mL dropping funnel, was charged
with magnesium turnings (10.8 g, 450 mmol), which were covered
with anhyd THF (50 mL). Then 2-bromopropane (18.5 g, 150
mmol) was added dropwise at r.t. in THF (200 mL). After stirring
overnight, the dropping funnel was replaced by a rubber septum. To
separate the reagent from the remaining magnesium turnings, the
Grignard solution was transferred via a transfer-needle into another
dry, argon flushed, 500 mL Schlenk flask equipped with a rubber
septum. For storage of the iso-propylmagnesium bromide solution,
the rubber septum was replaced by a glass stopper. The concentra-tion
of i-PrMgBr was determined by the method of Paquette.
A dry and argon flushed 50 mL round-bottom flask, equipped with
a magnetic stirring bar, was charged with methyl 4-iodobenzoate (2:
788 mg, 3 mmol) in anhyd THF (6 mL) and cooled to –20 °C. i-PrMgBr
(6.2 mL, 0.54 M in THF, 3.3 mmol) prepared as described
above, was slowly added. After 1 h, the exchange was complete (as
indicated by GC analysis of reaction aliquots).
The rate of the iodine-magnesium exchange is significantly slower than the iodine-lithium exchange,8 and it is observed that the nature of the aromatic or heteroaromatic ring strongly influences the rate of the exchange. The more electron-poor the aromatic ring, the faster is the exchange reaction. Also, the presence of chelating groups ortho- to the carbon-halogen bond strongly accelerates the exchange and allows the bromine-magnesium exchange to take place under milder conditions than usual. In general, iodine-magnesium exchange reactions are considerably faster than the corresponding bromine-magnesium exchange (Scheme 2).
So... as you can see, the conditions will have to bee optimized for methoxylated (electron-rich) rings - but, perhaps, that would bee even better - like doing the rxn at RT??
Anyway, i think this all is pretty cool :)
Antoncho