- Lithiation reactions catalyzed by linear and cross-linked arene-based polymers. Generation of functionalized organolithium compounds
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Lithiation of various substrates, such as chlorinated acetals, α-chloro ether, dichloro derivatives benzo-fused heterocycles, and allyl and benzyl derivatives, with excess lithium powder in the presence of a catalytic amount of soluble linear or insoluble cross-linked arene (naphthalene or biphenyl)-based polymers yields the expected organolithium intermediates. The latter react with electrophiles either in two steps or under Barbier-type reaction conditions to afford the corresponding adducts. The catalyst is easily recuperated by filtration at the end of the process, and the procedure can be regarded as a reasonable alternative to the use of free arenes as electron carrier in lithiation reactions.
- Candela,Gomez,Yus
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p. 795 - 801
(2007/10/03)
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- Polyphenylene as an electron transfer catalyst in lithiation processes
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The lithiation of different functionalised chlorinated materials (1a-c), dichlorinated compounds (1d-f) and benzofused cyclic ethers (1g,h) with lithium powder in the presence of catalytic amounts of either linear (LPP) or crosslinked (CPP) polyphenylene, in THF at temperatures ranging between -78 and 20°C, leads to the expected organolithium intermediates (Ia-h), which by reaction with electrophiles [ButCHO, PhCHO, Et2CO, (CH2)5CO, PhCOMe, Me3SiCl] gives, after hydrolysis with water, the expected products 2aa-hf.
- Yus, Miguel,Gómez, Cecilia,Candela, Pablo
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p. 6207 - 6210
(2007/10/03)
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- Polymer supported arene-catalysed lithiation reactions
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The reaction of functionalised mono or dichlorinated materials 1a-6a with an excess of lithium and a catalytic amount of a naphthalene (P(N)) or biphenyl (P(B)) supported polymer (easily prepared by radical copolymerisation of 2-vinylnaphthalene or 4-vinylbiphenyl with vinylbenzene and divinylbenzene) in THF either in the presence or not of different electrophiles [Me3SiCl, (i)prCHO, PhCHO, Et2CO, (CH2)4CO, (CH2)5CO, (c- C3H5)2CO, (i)Pr2CO, PhCOMe, PhCH=NPh] at -78 or -50°C leads, after hydrolysis with water, to the expected functionalised products 1ca-6ck. The polymeric catalyst is quantitatively recovered and can reused several times without any loss of activity.
- Gomez, Cecilia,Ruiz, Sonia,Yus, Miguel
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p. 7017 - 7026
(2007/10/03)
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- DTBB-catalysed lithiation of chlorinated benzylic chlorides, alcohols, thiols or amines
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The reaction of chlorinated benzyl chlorides (I) with an excess of lithium powder and a catalytic amount of DTBB (4 mol %) in the presence of different electrophiles [Pr(i)CHO, Bu(t)CHO, Et2CO, (CH2)5CO, PhCOMe, Me3/
- Gomez, Cecilia,Huerta, Fernando F.,Yus, Miguel
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p. 1853 - 1866
(2007/10/03)
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- Polymer supported naphthalene-catalysed lithiation reactions
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The reaction of functionalised mono or dichlorinated materials 1a-6a with an excess of lithium and a catalytic amount of a naphthalene supported polymer (P-152, easily prepared by radical copolymerisation of 2-vinylnaphthalene, styrene and divinylbenzene) in THF either in the presence (Barbier-type conditions) or not of different electrophiles [Me3SiCl, Bu(n)CHO, Bu(i)CHO, PhCHO, Et2CO, c(C3H5)2CO, Pr(i)2CO, (CH2)4CO, (CH2)5CO, PhCOMe, PhCH=NPh] leads, after hydrolysis, to the expected products 1c-6c. The catalyst is quantitatively recovered and can be reused several times without any loss of its activity.
- Gomez, Cecilia,Ruiz, Sonia,Yus, Miguel
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p. 1397 - 1400
(2007/10/03)
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- Lithiated benzyllithiums from chlorobenzyl chlorides by a DTBB-catalysed lithiation
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The reaction of 2-, 3- or 4-chlorobenzyl chlorides (1a-c) with an excess of lithium and a catalytic amount of DTBB (7 mol%) in the presence of different electrophiles [Pr(i)CHO, Bu(t)CHO, Et2CO, (CH2)5CO, PhCOMe, Me3SiCl] in THF at -50°C leads after hydrolysis with water, to the expected dioles or disilylated compounds 2aa-2cf.
- Gomez, Cecilia,Huerta, Fernando F.,Yus, Miguel
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p. 687 - 690
(2007/10/03)
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