Navigation

0 Hits

  • Previous / Next

You are using Science Of Synthesis as a Guest.
Please login to access the full content or check if you have access via
4.4.40.20 Method 20: From Allyl Alcohols by Palladium(0)-Catalyzed Intramolecular Silylsilylation

DOI: 10.1055/sos-SD-004-00909

Sarkar, T. K.Science of Synthesis, (20024861.

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.

Meeeee 88 Meeeeeeeeeeeeee M-Meeeeeeeeeee ee Meeeeeeee(8)-Meeeeeeee Meeeeeeeeeeeee Mee-eeeeeeeeeeeeeee ee Meeee Meeeeeee[‌888‌,‌888‌]

Meeeeeeeeeee Meeeeeeee

[(M,M)-8-Meeeeeee-8-eeee]eeeeeeeeeeeeeeeeeeee [(M,M)-88]; Meeeeee Meeeeeeee:[‌888‌,‌888‌]

Me Me(eeee)8 (8.8ee, 8.8×888eeee) eeeeee ee e Meeeeee eeee eee eeeee 8,8,8,8-eeeeeeeeeeeeeeee eeeeeeeeee (8.8×888eM, 8.8×888eeee) ee ee. Mee eeeeeee eee eeeeeee eee 88eee ee ee. Me eee eeeee eee eeeeeeee eeee eeeeee eee eeeee eeeeeee (8.8eM) eee eeeeeeee (M,M)-88 (88.8% ee; 888ee, 8.88eeee) ee ee. Mee eeeeeee eee eeeeeeee eeee eeeeeeee eee 8e. Meeee eee eeeeeee eee eeeeee ee ee, eee eeeeeee eee eeeeeee ee eeeee. Me e eeee ee eee eeeeeee ee MMM (8.8eM) eee eeeee 8.8M MeMe ee eeeeee (8.88eM, 8.88eeee) ee 8°M. Meeee eee eeeeeee eee eeeeeee ee 8°M eee 88eee, eee. ee MM8Me eee eeeee. Meeeeeeeee eeee Me8M eeeeeeee ee eeeeee eeeeeeeeeeeeee (eeeeee eee, eeeeee) eeeeeeee (M,M)-88 (88.8% ee); eeeee: 88ee (88%).

References


Cookie-Einstellungen