Trimethylsilyl-3-trimethylsilyloxy- 1-propene

Y Tsuji, Y Kakehi, T. Kobayashi, M. Shinkai, Y Ebihara, M. Kawamura, T., Chem. Soc., Perkin Trans. 1995, 599. 

(Babu) RajanBabu The Ohio State University, Columbus, OH, USA 

Seunghoon Shin Hanyang University, Seoul, Korea 

Preparative Methods allyl trimethylsilyl ether is lithiated with s-butyllithiumin TFIF-FIMPA to give a rapidly equilibrating mixture of a carbanion and a silylallyloxy anion (eq 1). Silylation of the mixture with chlorotrimethylsilane affords 3-trimethylsilyl-3-trimethylsilyloxy-l-propene (1) exclusively. Several other derivatives with bulky substituent(s) on the silyloxy group were also prepared.  

Homoenolate Anion Equivalent. The reaction of (1) with acid chlorides in the presence of titanium(IV) chloride affords the corresponding y-keto aldehydes after hydrolysis (eq 2) O-Acylation to form the 1-silyl allyl ester (17-30%) competes with the Se alkylation of the double bond. Bulkier silyloxy derivatives give y-keto aldehydes in higher yield. 

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Under catalysis by tris(dimethylaminosulfonium)difluorotrimethylsilicate, 1,5-anhydro-4,6-0-benzylidene-2-deoxy-D-ery//iro-hex-3-ulo-l-enitol reacted with the ketene acetal, l-methoxy-2-methyl-l-(trimethylsilyloxy)-propene, by Michael reaction at C-1 and gave 23. When the catalyst involved was trimethylsilyl triflate the branched derivatives 24 and 25 unexpectedly resulted. These latter products were thought to arise by a trimethylsilyl triflate induced non-selective cleavage of the benzylidene acetal of the initially formed intermediate 23 affording 4-0- and 6-0-benzylic carbenium ions which underwent a subsequent ring closure at C-2. (See Chapter 13 for reaction of the same ketene acetal with glycals). ... 

Chelation control, as indicated in 5, is also a suitable model for rationalizing the stereochemical outcome of titanium tetrachloride mediated additions of 3,3-dimelhyl-2-trimethylsilyl-oxy-l-butenc (6) or l-methoxy-2-methyl-l-trimethylsilyloxy-l-propene (7) to 3-benzyloxy-2-methylpropanal (4). In both cases, there is almost exclusive formation of the chelate-controlled product (95 5 and >97 3, respectively)13. 

Dithioacetals derived from alkyl aryl ketones react with the Grignard reagent (1) in the presence of a nickel catalyst. The use of an orthothioester as substrate in place of a thioacetal provides l,3-bis(trimethylsilyl)propenes as a mixture of the ( )- and (Z)-isomers. With a-oxoketene dithioacetals (5), the Grignard reagent (1) reacts, in the presence of copper(I) iodide, to provide l-trimethylsilyloxy-3-thiadienes (eq 9). ... 

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