Silanes allyltrimethyl

Titanium tetrachloride Titanium chloride (8,9) (7550-45-0) Allyltrimethylsilane Silane, allyltrimethyl- (8) SHane, trlmethyl-2-propenyl- (9) (762-72-1)... 

Trimethylsilylated allylic alcohols such as 804 react readily with allyltrimethyl-silane 82 in the presence of ZnCl2 in CH2CI2 to give, after 1.5 h at 25 °C, an approximately ca. 22 78 mixture of 805 and 806 in 94% yield, and HMDSO 7 [17]. 

The 0/7/fo-alkylation of aromatic ketones with olefins can also be achieved by using the rhodium bis-olefin complex [C5Me5Rh(C2H3SiMe3)2] 2, as shown in Equation (9).7 This reaction is applied to a series of olefins (allyltrimethyl-silane, 1-pentene, norbornene, 2,2 -dimethyl-3-butene, cyclopentene, and vinyl ethyl ether) and aromatic ketones (benzophenone, 4,4 -dimethoxybenzophenone, 3,3 -bis(trifluoromethyl)benzophenone, dibenzosuberone, acetophenone, />-chloroacetophenone, and />-(trifluoromethyl)acetophenone). 

A more recent synthesis of 197 [365] is shown in Fig. 9. Enders introduced the stereogenic centre of (S)-lactic acid into the crucial position 10 in 197. The vinylsulfone B, readily available from lactic acid, was transformed into the planar chiral phenylsulfonyl-substituted (q3-allyl)tetracarbonyliron(+l) tetra-fluoroborate C showing (IR,2S,3 )-configuration. Addition of allyltrimethyl silane yielded the vinyl sulfone D which was hydrogenated to E. Alkylation with the dioxolane-derivative of l-bromoheptan-6-one (readily available from 6-bro-mohexanoic acid) afforded F. Finally, reductive removal of the sulfonyl group and deprotection of the carbonyl group furnished 197. A similar approach was used for the synthesis of 198 [366]. 

Fig. 21 Synthesis of 4-acetamido tetrahydropyran by using allyltrimethyl silane...

Trimethylsilyl ethers and esters.i The reaction of alcohols and allyltrimethyl-silane in acetonitrile with TsOH as catalyst (70 80°, 1 3 hours) results in trimethyl-silyl ethers in 85-95% yield with elimination of propene. The same reaction with carboxylic acids results in trimclhylsilyl esters. Phenols do not undergo this reaction. 

Upon treatment with TiCl3(OCHMe2), compound 32 reacts with allyltrimethyl-silane to form ether 33 in good yield and selectivity. The chiral template is then removed by treatment with an excess of LDA affording the desired homoallylic alcohol 34 in 80-94% ee. 

Nucleophile = Et3SiH, allyltrimethyl silane, Me3SiCN, MeOH Scheme 82... 

The starting allyltrimethyl silane can be prepared in satisfactory yield by the procedure of Sommer. It can also be purchased from PCR Inc., Aldrich Chemical Company, Inc., Fluka A. G., Petrarch Systems Inc., and Tokyo Kasei Kogyo Co., Ltd. The checkers employed material from Petrarch. 

The reaction of several a,/ -unsaturated ketones with allyltrimethyl silane in either [C4Ciim][BF4] or [C4Ciim][PF6] has been compared with several classical solvents, see Scheme 9.45.[152] With indium(III) chloride as catalyst, only in some cases was a higher activity observed in the ionic liquids, but the differences relative to the commonly used solvent, dichloromethane, were small and no obvious advantage in performing the reaction in the ionic media was evident. Very high catalyst loadings, ca. 20-50 mol%, were used but no attempts were made to recycle the catalyst phase. 

METHYL KETONES Allyltrimethyl-silane. Bis(acetonitrilo)chloronitro-pailadium(II). Dicarbonylbis(triphenyl-phosphine)nickel. Dichloro-dicyano-benzoquinone. Hydrogen peroxide-Palladium acetate. Meldrum s acid. Palladium r-butyl peroxide trifluoro-acetate. Palladium(Il) chloride. 

KETO ALDEHYDES Allyltrimethyl-silane. (S)-(+)-p-Tolyl-p-tolylthiomethyl sulfoxide. 

WACKER OXIDATION Allyltrimethyl-silane. Bis(acetonitrile)chloronitro-palladiumUI). Palladium(II) chloride. Triethylborane. 

Within the past decade, diastereosolective radical reactions have become feasible and the factors contolling selectivity defined. Chiral auxiliaries for radical reactions have been recently developed in analogy to those developed for carban-ion chemistry in the 1970s and 1980s. The first example of stoichiometric use of a chiral ligand for enantioselective radical additions was recently reported by Porter and coworkers [59,60,61]. Reaction of the amide 14 with allyltrimethyl-silane at -78 °C, initiated by triethylborane, in the presence of 1 equiv. each of zinc triflate and the chiral bidentate ligand 15, provided the allylated product in a yield up to 88% and ee of 90%, Eq. (18). The presumed intermediate is the a-keto radical complexed to the chiral Lewis acid. 

The [ 2 + 2] photocycloaddition of 1,4-naphthoquinone to allyltrimethyl-silane has been described, and irradiation of 1,2-bis[trimethylsilyloxy]-... 

Displayed below is a representative mechanism for the reaction between allyltrimethyl-silane and ketone in the presence of Lewis acid TiCU. 

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