106989-75-7Relevant academic research and scientific papers
Stereoselective alcohol silylation by dehydrogenative Si-O coupling: Scope, limitations, and mechanism of the Cu-H-catalyzed non-enzymatic kinetic resolution with silicon-stereogenic silanes
Rendler, Sebastian,Plefka, Oliver,Karatas, Betuel,Auer, Gertrud,Froehlich, Roland,Mueck-Lichtenfeld, Christian,Grimme, Stefan,Oestreich, Martin
supporting information; experimental part, p. 11512 - 11528 (2009/12/07)
Ligand-stabilized copper(I)hydride catalyzes the dehydrogenative Si-O coupling of alcohols and silanes-a process that was found to proceed without racemization at the silicon atom if asymmetrically substituted. The present investigation starts from this pivotal observation since silicon-stereogenic silanes are thereby suitable for the reagent-controlled kinetic resolution of racemic alcohols, in which asymmetry at the silicon atom enables discrimination of enantiomeric alcohols. In this full account, we summarizeour efforts to systematically examine this unusual strategy of diastereoselective alcohol silylation. Ligand (sufficient reactivity with moderately electron-rich monophosphines), silane (reasonable diastereocontrol with cyclic silanes having a distinct substitution pattern) as well as substrate identification (chelating donor as a requirement) areintroductorily described. With these basic data at hand, the substrate scope was defined employing enantiomerically enriched tert-butyl-substituted 1-silatetraline and highly reactive 1-si-laindane. The synthetic part is complemented by the determination of the stereochemical course at the silicon atom in the Si-O coupling step followed by its quantum-chemical analysis thus providing a solid mechanistic picture of this remarkable transformation.
Stereoselective and competitive [1,2]- and [2,3]-wittig rearrangements of allyl heteroarylalkyl ethers
Capriati, Vito,Florio, Saverio,Ingrosso, Giovanni,Granito, Catia,Troisi, Luigino
, p. 478 - 484 (2007/10/03)
Several allyl heteroarylalkyl ethers have been synthesized and then deprotonated with nBuLi in THF at -78°C to give lithium derivatives. The lithium-bearing terminus was either the α- or the α′-carbon atom, depending on the associated proton acidity. In the absence of an external electrophile, a sigmatropic rearrangement occurs, generating a new C-C bond. Heteroarylalkyl homoallylic alcohols and allyl heteroarylalkylic alcohols were obtained as products of stereoselective [2,3]- or [1,2]-Wittig rearrangements, respectively. Homoallylic alcohols were obtained in high yields and with fairly good enantiomeric enrichments when the reactions were carried out in toluene with (-)-sparteine as the external chiral ligand.
