- Functionalized organolithium compounds of DTBB-catalyzed sulfur-lithium exchange
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The successive reaction of β- or γ-hydroxy or amino phenyl thioethers (1,4) with butyllithium and an excess of lithium powder in the presence of a catalytic amount of DTBB in THF at - 78°C leads to the formation of the corresponding β- or γ-functionalized organolithium compounds 2 or 5, respectively, which by treatment with different electrophiles [D2O, t- BuCHO, PhCHO, Me2CO, (CH2)4CO, (CH2)5CO] at temperatures ranging between - 78°C and room temperature yields, after hydrolysis with water, the expected functionalized alcohols or amines 3 or 6, respectively, in a completely regioselective manner.
- Foubelo, Francisco,Gutiérrez, Ana,Yus, Miguel
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p. 503 - 514
(2007/10/03)
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- 4,4'-Di-tert-butylbiphenyl-Catalysed Reductive Opening of Azetidines with Lithium: A Direct Preparation of 3,N-Dilithioalkylamines
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The reaction of N-phenylazetidine 1a with an excess of lithium powder and a catalytic amount of 4,4'-di-tert-butylbiphenyl (5 molpercent) in THF at -15 deg C leads to the corresponding dianion 2a, which by treatment with different electrophiles (H2O, D2O, ButCHO, PhCHO, (CH2)5CO, PhCH=NPh, CO2) yields, after hydrolysis with water, the expected functionalysed amines 3aa-ah.The same method applied to N-isopropyl-2-phenylazetidine 1c affords compounds 3ca-ce (electrophiles: H2O, D2O, PhCHO, Me2CO, CH2=CHCH2Br) resulting from the more stable benzylic intermediate 2c.Finally, the regiochemistry in the reductive opening of 2-methyl-N-phenylazetidine 1d followed by deuterolysis was studied: a mixture of both regioisomers 3da+3da' was obtained, the ratio being the oposite as expected according to the stability of both intermediates 2d and 2d'.
- Almena, Juan,Foubelo, Francisco,Yus, Miguel
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p. 5775 - 5782
(2007/10/02)
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