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Please login to access the full content or check if you have access via4.4.40.20 Method 20: From Allyl Alcohols by Palladium(0)-Catalyzed Intramolecular Silylsilylation
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Sarkar, T. K., Science of Synthesis, (2002) 4, 861.
1,3-Unsymmetrically substituted E-allylsilanes have been prepared by palladium-catalyzed intramolecular silylsilylation of allyl alcohols and subsequent Peterson-type elimination with organolithium reagents. This protocol involving 1,3 chirality transfer is equally applicable to the synthesis of enantioenriched allylsilanes. For example, the intramolecular silylsilylation of (R,E)-75 (99.7% ee) promoted by a catalyst generated in situ from bis(acetylacetonato)palladium(II) and 1,1,3,3-tetramethylbutyl isocyanide gives a 1:1 mixture of allylsilane (S,E)-78 (99.1% ee) and cyclic siloxane 77, presumably through the highly stereoselective formation of four-membered ring 76 followed by its thermal disproportionation (Scheme 35).[138,139] Subsequent treatment of the mixture with butyllithium yields allylsilane (S,E)-78 (99.1% ee) from 77 without contamination from its Z-isomer. Similarly, (R,E)-78 (95.4% ee)[138] is available from (R,Z)-75 (96.0% ee). The substrates for these reactions have been prepared by reactions of the corresponding alcohols with 1-chloro-1,1,2-triphenyl-2,2-dimethyldisilane in the presence of triethylamine and a catalytic amount of 4-dimethylaminopyridine.
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Meeeeeeeeeee Meeeeeeee
[(M,M)-8-Meeeeeee-8-eeee]eeeeeeeeeeeeeeeeeeee [(M,M)-88]; Meeeeee Meeeeeeee:[888,888]
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References
[138] | Meeeeeee, M.; Meeeeeeee, M.; Mee, M., M. Me. Meee. Mee., (8888) 888, 8888. |
[139] | Meeeeeee, M.; Meeeeee, M.; Meeeeeeee, M.; Mee, M., Meeeeeeeeee: Meeeeeeee, (8888) 8, 888. |
[140] | Meeeeeee, M., eeeeeeee eeeeeeeeeeeee. |