TY - JOUR
T1 - Synthesis, Reactivity, and NMR Studies of Dilithiated (E)-1, 4-Bis(trimethylsilyl)but-2-ene and (E)-1,4-Bis(trimethylsilyl)-2,3-dimethylbut-2-ene
AU - Field, Leslie D.
AU - Gardiner, Michael G.
AU - Kennard, Colin H.L.
AU - Messerle, Barbara A.
AU - Raston, Colin L.
PY - 1991/9/1
Y1 - 1991/9/1
N2 - (Z)-1, 4-Dilithio-1,4-bis(trimethylsilyl)but-2-ene and 1,4-dilithio-1,4-bis(trimethylsilyl)-2,3-dimethylbut-2-ene adducts of TMEDA (≡N,N,N′,′-tetramethylethylenediamine), [{Li(TMEDA)}2{(Me3SiCHCH)2}] (3) and [{Li(TMEDA)}2((Me3SiCHCMe)2}] (4), respectively, have been prepared by dimetalation of the corresponding (E)-but-2-ene using n-BuLi(TMEDA) in hexane. Assignment of the Z configuration of the dianions with Li atoms bridging the ipso carbons (C1,4) is based on NMR data: Magnetically equivalent protons attached to the ipso carbons (C1,4) couple to 7Li (2JLi-H = ca. 1 Hz) in both compounds, lack of coupling of the protons attached to C2,3 with the lithiums in 3, and NOE enhancements for 1H−7Li HOESY experiments. The Z configuration is also consistent with the structures of two isolated silyl derivatives of 3; treatment with ClSiMe3 gives (Z)-1,1,4, 4-tetrakis(trimethylsilyl)but-2-ene (5), and with Cl2SiMe2 it yields the (Z, Z)-1, 6-disilacyclodeca-3, 8-diene [(Me3SiCHC(H)=C(H)CH(SiMe3)SiMe2}2] (6). Compound 3 is a potent reducing agent, affording (E, E)-1, 4-bis(trimethylsilyl)buta-1, 3-diene (7) and metal when treated with HgCl2 (yield of 7 71%) or CaCl2. X-ray diffraction data for 5 revealed a distorted Z double bond, the C-C-C angles at the sp2 carbon centers being “opened up” to 130.2° (mean): Crystals are monoclinic, space group P21/n, with α = 11.595 (4) Å, b = 12.205 (1) Å, c = 17.569 (6) Å, β = 107.33 (2)°, V = 2373 (1) Å3, and Z = 4.
AB - (Z)-1, 4-Dilithio-1,4-bis(trimethylsilyl)but-2-ene and 1,4-dilithio-1,4-bis(trimethylsilyl)-2,3-dimethylbut-2-ene adducts of TMEDA (≡N,N,N′,′-tetramethylethylenediamine), [{Li(TMEDA)}2{(Me3SiCHCH)2}] (3) and [{Li(TMEDA)}2((Me3SiCHCMe)2}] (4), respectively, have been prepared by dimetalation of the corresponding (E)-but-2-ene using n-BuLi(TMEDA) in hexane. Assignment of the Z configuration of the dianions with Li atoms bridging the ipso carbons (C1,4) is based on NMR data: Magnetically equivalent protons attached to the ipso carbons (C1,4) couple to 7Li (2JLi-H = ca. 1 Hz) in both compounds, lack of coupling of the protons attached to C2,3 with the lithiums in 3, and NOE enhancements for 1H−7Li HOESY experiments. The Z configuration is also consistent with the structures of two isolated silyl derivatives of 3; treatment with ClSiMe3 gives (Z)-1,1,4, 4-tetrakis(trimethylsilyl)but-2-ene (5), and with Cl2SiMe2 it yields the (Z, Z)-1, 6-disilacyclodeca-3, 8-diene [(Me3SiCHC(H)=C(H)CH(SiMe3)SiMe2}2] (6). Compound 3 is a potent reducing agent, affording (E, E)-1, 4-bis(trimethylsilyl)buta-1, 3-diene (7) and metal when treated with HgCl2 (yield of 7 71%) or CaCl2. X-ray diffraction data for 5 revealed a distorted Z double bond, the C-C-C angles at the sp2 carbon centers being “opened up” to 130.2° (mean): Crystals are monoclinic, space group P21/n, with α = 11.595 (4) Å, b = 12.205 (1) Å, c = 17.569 (6) Å, β = 107.33 (2)°, V = 2373 (1) Å3, and Z = 4.
UR - http://www.scopus.com/inward/record.url?scp=0001435781&partnerID=8YFLogxK
U2 - 10.1021/om00055a035
DO - 10.1021/om00055a035
M3 - Article
AN - SCOPUS:0001435781
VL - 10
SP - 3167
EP - 3172
JO - Organometallics
JF - Organometallics
SN - 0276-7333
IS - 9
ER -