General Method for the Reaction of Carboxylic Acids 1
with Methyllithium, Followed by Treatment with Chlorotrimethylsilane
(Me3SiC1).
A stirred solution of 2 mmol of
carboxylic acid 1 in 15 & of dry THF was cooled to 0 OC (ice bath) and treated rapidly (ca. 15 s) with
8 mmol of methyllithium (Aldrich,1.4 M in ether). After 2 h at 0 OC, 5 mL (40 mmol) of freshly distilled Me3SiCl was rapidly
added while stirring continued. The ice bath was then removed
and the reaction mixture allowed to come to room temperature
at which point 15 mL of 1 N HCl was added, and the resulting
two-phase system was stirred at room temperature for 0.5 h. The
mixture was then transferred into a separatory funnel and extracted
with 25 mL of diethyl ether. The aqueous layer was then
extracted with two additional 25-mL portions of diethyl ether,
the ethereal layers were combined and washed with 20 mL of
water, and the organic layer was dried. Filtration and removal
of solvent from the filtrate in vacuo gave crude methyl ketone
2, which was purified by the appropriate method (see below).
[ Last edited by cherishmei on 2009-10-9 at 21:47 ]，
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这个反应产率一般不高，我做过的20-30左右，一般甲基锂可用2-3倍量，冰浴下缓慢滴加到羧酸的THF溶液中（注意氮气保护），后处理可用饱和氯化铵容易淬灭！
我看了一篇文献，里面甲基锂加了4当量，我很奇怪，难道不会生成三级醇么？这是其一；
其二他是迅速滴加，这我也很疑惑，一般都是缓慢滴加，而他是迅速（ms越快越好），这个我也不太清楚
请大虾明示！谢谢
General Method for the Reaction of Carboxylic Acids 1
with Methyllithium, Followed by Treatment with Chlorotrimethylsilane
(Me3SiC1).
A stirred solution of 2 mmol of
carboxylic acid 1 in 15 & of dry THF was cooled to 0 OC (ice bath) and treated rapidly (ca. 15 s) with
8 mmol of methyllithium (Aldrich,1.4 M in ether). After 2 h at 0 OC, 5 mL (40 mmol) of freshly distilled Me3SiCl was rapidly
added while stirring continued. The ice bath was then removed
and the reaction mixture allowed to come to room temperature
at which point 15 mL of 1 N HCl was added, and the resulting
two-phase system was stirred at room temperature for 0.5 h. The
mixture was then transferred into a separatory funnel and extracted
with 25 mL of diethyl ether. The aqueous layer was then
extracted with two additional 25-mL portions of diethyl ether,
the ethereal layers were combined and washed with 20 mL of
water, and the organic layer was dried. Filtration and removal
of solvent from the filtrate in vacuo gave crude methyl ketone
2, which was purified by the appropriate method (see below).
[ Last edited by cherishmei on 2009-10-9 at 21:47 ]，
为何不用－ＣＮ来制备呢？