135730-49-3Relevant academic research and scientific papers
The first asymmetric halogen/metal-exchange reaction: Desymmetrization of alcohols with enantiotopic bromoarene substituents
Saelinger, Daniel,Brueckner, Reinhard
experimental part, p. 6688 - 6703 (2010/02/28)
Desymmetrizations of the prochiral bis(bromoaryl)alcohols 1 and 4 were effected by treatment with iPr2Mg and enantiomerically pure lithium alkoxides. The resulting arylmagnesium compounds were quenched with various electrophiles. The absolute and (if relevant) relative configurations of the resulting products were determined. The best ee/yield combination was obtained for the protonolysis furnishing monobromoalcohol (R)-2 (53% ee, 51% yield). The latter was converted into (R)-orphenadrine, an antihistaminic and anticholinergic drug.
Chemoselective Addition of Organotitanium Reagents to Carbonyl Compounds
Reetz, Manfred T.,Westermann, Juergen,Steinbach, Rainer,Wenderoth, Bernd,Peter, Roland,et al.
, p. 1421 - 1440 (2007/10/02)
The conversion of classical carbanions such as RMgX, RLi, or deprotonated nitriles, sulfones, and carboxylic esters into titanium analogs results in reagents which add chemoselectively to carbonyl compounds in the presence of other functional groups.The standard titanating agent is chlorotriisopropoxytitanium (1).Grignard-type reactions and aldol additions are aldehyde-selective in the presence of ketones.Other functional groups such as alkyl and aryl halides, esters, amides as well as nitro and cyano moieties are tolerated.Discrimination between two aldehydes or two ketones is also possible.Replacing alkoxy ligands by methyl groups at titanium increases reactivity dramatically, relative rates increasing in the series CH3Ti(OCHMe2)3 (CH3)2Ti(OCHMe2)2 (CH3)4Ti.The latter reagent and its zirconium analog methylate sterically hindered and/or enolizable ketones which normally fail to undergo Grignard reactions.The ate complex H2C=CHCH2Ti(OCHMe2)4MgCl (63) is aldehyde-selective, while the amino analog H2C=CHCH2Ti(NMe2)4MgCl (64) adds selectively to ketones in the presence of aldehydes.
