135562-44-6Relevant articles and documents
Deoxygenation of alcohols employing water as the hydrogen atom source
Spiegel, David A.,Wiberg, Kenneth B.,Schacherer, Laura N.,Medeiros, Matthew R.,Wood, John L.
, p. 12513 - 12515 (2005)
Trialkylboranes (BMe3, BEt3, and BBu3) have been shown to mediate reductive deoxygenation reactions of O-alkyl-S-methyl dithiocarbonates (methyl xanthates) in which water or deuterium oxide functions as the source of hydrogen or deuterium. This method has proven versatile with regard to substrate scope and is capable of providing protio- or deuterioalkane products in high yields with excellent levels of D-incorporation. Ab initio calculations suggest that the trialkylborane-water complex possesses an unusually low O-H bond dissociation energy (73 kcal/mol) and support a radical chain mechanism for this process. Taken together, this report provides evidence for fundamentally novel and previously overlooked modes of reactivity for water and trialkylboranes of wide ranging importance in both theoretical and applied investigations. Copyright
Enantio- and Diastereoselective α-Metallation of Prochiral Sulfoxides by (+)-Menthyllithium
Maercker, Adalbert,Schuhmacher, Rudolf,Buchmeier, Willi,Lutz, Heinz Dieter
, p. 2489 - 2498 (2007/10/02)
Six out of ten prochiral dialkyl sulfoxides 3 with diastereotopic α methylene protons were stereoselectively metallated by (+)-menthyllithium (11) to yield two diastereomeric pairs of enriched enantiomers 29 after the reaction with benzophenone.The maximum e.e. was 40percent.Dicyclohexyl sulfoxide (3c) was deprotonated enantioselectively with an e.e of 30percent. 2-Bornyllithium (21) was unsuccesful as a chiral base and was shown for the first time to contain 4percent of isobornyllithium (22).The reactions were performed in pentane at -80 deg C; in diethyl ether and THF the e.e's were only slightly higher, and at higher temperatures the selectivity was rapidly decreasing.It was shown that racemization takes place by an intermolecular transmetallation reaction.The structure of 29f (n = 3) was elucidated by an X-ray analysis.Key Words: (+)-Menthyllithium, stereoselective metallation with/ Prochiral sulfoxides, enantio- and diastereoselective α-deprotonation of / 2-Bornyllithium, content of isobornyllithium in / Racemization, mechanism by intermolecular transmetallation/ e.e., temperature dependence of
