Akira Hosomi

Regiospecific allylation of acetals with allylsilanes catalyzed by iodotrimethylsilane. Synthesis of homoallylethers

Abstract Allylation of acetals with allylsilanes is catalyzed by iodotrimethylsilane to give the corresponding homoallyl ethers, with regiospecific transposition of the allyl group.

Highly stereoselective c-allylation of glycopyranosides with allylsilanes catalyzed by silyl triflate or iodosilane

Abstract Methyl α-D-glucopyranoside, methyl α-D-mannopyranoside and, in particular, the corresponding α-D-glycopyranosyl chlorides readily undergo allylation with allylsilanes catalyzed by trimethylsilyl triflate or iodotrimethylsilane in a highly stereoselective mode.

2-Alkoxycarbonylallyltrimethylsilanes as new reagents of 2-alkoxycarbonylallylation of electrophiles

Abstract 2-Alkoxycarbonylallylsilanes are useful for 2-alkoxycarbonylallylation of acetals and carbonyl compounds with an aid of a Lewis acid; the products can be readily converted to α-methylene-γ-butyrolactones.

Stereoselective synthesis of 3-(d-glycopyranosyl)propenes by use of allylsilanes

Abstract Reactons of allylsilanes with methylpyranosides and pyranosyl chlorides proceeded very smoothly in the presence of a catalytic amount of trimethylsilyl trifluoromethanesulfonate and iodosilane to dive the corresponding glycopyranosyl-3-propenes in highly stereoselective mode. The configuration depends upon the structure of allylsilanes. 2-Bromo-2-propenyltrimethylsilane, the lowest nucleophile among the allylsilanes used, afforded an almost pure C -α- d -glycosyl compound.

Chemistry of organosilicon compounds—165 : 2-Trimethylsilyl-methyl-1, 3-Butadiene—A versatile building block for terpene synthesis

Abstract Two types of synthetically useful reactions of 2-trimethylsilylmethyl-1,3-butadiene (7) are discussed. Reactions of 7 with acid chlorides, aldehydes, ketones and acetals activated by a Lewis acid give isoprenylated compounds, while 7 undergoes the Diels-Alder reaction with dienophiles. High regiospecificity of the reaction qualifies 7 for a versatile building block of terpene synthesis.

Latent acetonylation of α,β -enones with allyltrimethylsilane or 2-methyl-2-propenyltrimethylsilane: synthesis of 1,5-diketones and annelation to fused cyclohexenones

Abstract Acetonylation of α,β-enones can be achieved by reactions either with (2-methyl-2-propenyl)trimethylsilane or with allyltrimethylsilane followed by oxidative cleavage of the double bond or by the Wacker reaction, respectively. Annelation of the 1,5-diketones is also described briefly.

Chemistry of organosilicon compounds: CC. Allyl coupling reactions of allylsilanes and allylstannanes with allylic halides, ethers and acetates promoted by a Lewis acid☆

Abstract Facile allyl couplings between allylsilanes or allylstannanes and various allylic substrates such as halides, ethers or acetates promoted by a Lewis acid, leading to 1,5-dienes with regiospecific transposition in the allylic part of allylmetallics have been observed. The combination of allylstannanes with allylic acetates promoted by bis(diethylaluminum) sulfate gives the most satisfactory results. The factors influencing the regioselectivity with respect to allylic substrates are discussed.

Stepwise conversion of oxiranes to allylic alcohols by iodotrimethylsilane and DBU

Abstract Iodotrimethylsilane, prepared from hexamethyldisilane and iodine reacts smoothly with oxiranes to give (2-iodoalkoxy)trimethylsilanes which can be converted to allylic alcohols with DBU in good yields. The whole conversion can be carried out in one-pot operation.

A novel aminomethylation of silyl enol ethers with aminomethyl ethers catalyzed by iodotrimethylsilane or trimethylsilyl trifluoromethanesulfonate

Abstract The iodotrimethylsilane-catalyzed reaction of silyl enol ethers with aminomethyl ethers in acetonitrile gives aminomethylation products of the corresponding ketones readily. The reaction can slso be catalyzed by trimethylsilyl trifluoromethanesulfonate in dichloromethane.

Pentadienylsilanes as new reagents of the siteselective dienylmethylation of electrophiles promoted by a Lewis acid

Abstract (2,4-Pentadienyl)- and (2,4-hexadienyl)trimethylsilanes, prepared from the corresponding pentadienylpotassiums and trimethylchlorosilane, react smoothly with various electrophiles such as acetals, aldehydes and acid halides to give pentadienylation products, with regiospecific transposition of the pentadienyl group.