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The Cationic Rearrangement of (3‐Hydroxy‐1‐propenyl)tris(trimethylsilyl)silanes into (1‐Trimethylsilyl‐2‐propenyl)bis(trimethylsilyl)silanols − Experimental and Theoretical Studies
Author(s) -
Schmohl Kathleen,
Wandschneider Dirk,
Reinke Helmut,
Heintz Andreas,
Oehme Hartmut
Publication year - 2002
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/1099-0682(200203)2002:3<597::aid-ejic597>3.0.co;2-3
Subject(s) - chemistry , trimethylsilyl , propenyl , medicinal chemistry , cationic polymerization , silanes , tris , isomerization , organic chemistry , catalysis , silane , biochemistry
(3‐Hydroxy‐1‐propenyl)tris(trimethylsilyl)silanes (Me 3 Si) 3 SiCH=CHCR 2 OH ( 8b,c ) ( b: R = Me; c: R = Ph) undergo a rapid rearrangement involving a 1,2‐Si,C migration of one trimethylsilyl group from the central silicon atom to a cationic neighboring carbon atom and a shift of the olefinic double bond, in the presence of acid, to afford (1‐trimethylsilyl‐2‐propenyl)bis(trimethylsilyl)silanols (Me 3 Si) 2 Si(OH)CH(SiMe 3 )CH=CR 2 ( 13b,c ). Treatment of 8b,c with sulfuric acid in methanol gives the methoxysilanes (Me 3 Si) 2 Si(OMe)CH(SiMe 3 )CH=CR 2 ( 14b,c ). In a related reaction, 8b,c are converted by boron trifluoride into the fluorosilanes (Me 3 Si) 2 SiFCH(SiMe 3 )CH=CR 2 ( 15b,c ). A possible mechanism of the isomerization reaction, involving the rearrangement of the silylcarbenium ions [(Me 3 Si) 3 SiCH=CHCR 2 ] + into the silylium ions [(Me 3 Si) 2 SiCH(SiMe 3 )CH=CR 2 ] + , is proposed. This is supported by calculations, which indicate the higher stability of the silylium ion 10b compared with the isomeric silylcarbenium cation 9b . For 14c the results of an X‐ray structural analysis are given.