Alcohols Organotitanium reagents

S)-2-Ethoxy-4-isopropyloxazoline, 129 Homoallylic alcohols Crotyldiisopinocampheylborane, 86 Dichlorobis( 1 -phenylethoxy) -titanium(IV), 12 Organotitanium reagents, 213 Tin(II) trifluoromethanesulfonate, 301 Homopropargylic alcohols Bis(2,4-dimethyl-3-pentyl) tartrate, 36... 

HOMOALLYLIC ALCOHOLS Cerium amalgam. Chromium(II) chloride. Fluorodimethoxyborane. Hypochlorous acid. Lithium bronze. Manganesc(II) chloride-Lithium aluminum hydride. Methylenetriphenylphosphorane. Organotitanium reagents. Tetrakis(triphenylphosphine)palladium. Tin. Tin(II) fluoride. 

Cleavage of acetals. The acetals derived from (2R,4R)-2,4-pentanediol (this volume) are cleaved by organotitanium reagents of the type RTiCI, or R,TiCf. with high chemo- and stereoselectivity. Removal of the chiral auxiliary gives chiral secondary alcohols in high purity. Acetals complexed with TiCb arc also cleaved by treatment with an alkyllithium. 

The above transformation has two different goals 21,22) 1) To increase chemo-, regio-, diastereo- and enantioselectivity in the reaction with carbonyl compounds (Sections C-E), and 2) to make certain reaction types amenable which do proceed readily with classical reagents, e.g., methylation of tertiary alkyl halides, alcohols and ethers, and direct geminal dialkylation of ketones (Section F). It turns out that organotitanium compounds are usually complementary to Li, Mg, Zn, Fe, Ni, Cu and Pd reagents. So far, experience in the above two areas points to the following positive aspects ... 

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