- Rhodium-catalyzed allylation of benzyl acetates with allylsilanes
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Benzyl acetate reacted with allyltrimethylsilane to give an allylation product in the presence of a catalytic amount of the (cyclooctadiene)rhodium(I) chloride dimer {[Rh(cod)Cl]2}, sodium tetrakis[3,5- bis(trifluoromethyl)phenyl]borate (NaBARF), and triphenyl phosphite [P(OPh) 3] in refluxing 1,2-dichloroethane. Primary, secondary and tertiary benzyl acetates could be used for the reaction. Moreover, allylation of gem-benzyl acetate was possible with [Rh(cod)Cl]2, NaBARF, and P(OPh)3. Monoallylation and diallylation of gem-benzyl acetate could be controlled by altering the reaction conditions. Cationic rhodium species generated in situ act as a Lewis acid catalyst to give a benzyl carbocation by elimination of the acetoxy group from the benzylic carbon. Copyright
- Onodera, Gen,Yamamoto, Eriko,Tonegawa, Shota,Iezumi, Makoto,Takeuchi, Ryo
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scheme or table
p. 2013 - 2021
(2011/10/09)
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- Reductive Alkylation/Arylation of Arylcarbinols and Ketones with Organosilicon Compounds
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Arylcarbinols react with certain organosilanes in the presence of boron trifluoride to yield hydrocarbons resulting from transfer of an R group from silicon to carbon.The transfer works well with aryl- and allylsilanes and fails with alkylsilanes.Allylation of ionizable carbinols is sometimes accompanied by cation-mediated oligomerization.This can be offset by converting the carbinols in question to their respective allyldimethylsilyl ethers followed by rearrangement of the ethers with BF3.While diaryl ketones are sluggishly bisallylated, the corresponding ketals undergo smooth bisallylation at 0 deg C with allytrimethylsilane/BF3/CH2Cl2.
- Cella, J. A.
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p. 2125 - 2130
(2007/10/02)
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