- Reactions of (Et2NCH2CH2NEt 2)·H2SiCl2 with selected diorganometallic reagents of magnesium and lithium
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Addition of the THF-insoluble di-Grignard reagent from 2,2′-dibromo- 4,4′-tert-butylbiphenyl (1) to a solution of [(teeda)·H 2SiCl2] in CH2Cl2/THF produced 2,7-di-tert-butyl-9H-9-silafluorene (3) in isolated, recrystallized yields of 2O, when reacted with [(teeda)·H2SiCl2] in CH2Cl 2/Et2O, gave similar yields of 5,10-dihydro-2,5,8- trimethylphenazasiline (4). In the absence of CH2Cl2 the major product produced from 1 was the spirocycle 2,2′,7,7′-tetra- tert-butyl-9,9′-spirobi[9H-9-silafluorene] both in a solvent-free form (5′) and as an ethanol solvate (5), both of which were crystallographically characterized. The spirocycle 2,2′,5,5′,8, 8′-hexamethyl-5,10-dihydro-10,10-spirobiphenazasiline (6) was formed from the reaction of the dilithio reagent of 2 in the absence of CH 2Cl2.
- Corey, Joyce Y.,Trankler, Kevin A.,Braddock-Wilking, Janet,Rath, Nigam P.
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experimental part
p. 5708 - 5713
(2011/02/16)
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- The superbase-mediated pairwise substitution of the 2,2′- and 6,6′-positions in a biphenyl derivative
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The superbasic mixture of butyllithium and potassium tertbutoxide is powerful enough to enable the double proton abstraction from one ortho and one ortho′ position of 4,4′-di-tert-butylbiphenyl. In this way, a series of functionalized derivatives becomes readily accessible, among them 4,4′-di-tert-butylbiphenyldiyl-2,2′-dicarboxylic acid (2a) and 4,4′-ditert-butylbiphenyl-2,2′-diol (2d). The latter compound can be subjected again to a superbase-promoted double metalation, thus giving rise to 2,2′,6,6′-tetrasubstituted biphenyl derivatives. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.
- Schlosser, Manfred,Mangano, Guiseppe,Leroux, Frederic
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p. 1014 - 1017
(2007/10/03)
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- NEW PRECURSORS TO SILAFLUORENES
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Conversion of 2,2'-dibromo-4,4'-di-t-butylbiphenyl and o-bromo-o'-chlorobiphenyl to organometallic reagents suitable for reaction with Me2SiCl2 to produce silafluorene has been developed.
- Corey, Joyce Y.,Chang, Lihsueh S.
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