619-52-3Relevant articles and documents
(-)-Menthol as a source of new N,N-diamine ligands for asymmetric transfer hydrogenation
Roszkowski, Piotr,Maurin, Jan K.,Czarnocki, Zbigniew
supporting information, p. 2184 - 2188 (2018/05/07)
The synthesis of new chiral N-monotosylated-1,2-diamines based on the (-)-menthol skeleton is presented. The elimination of HCl from neomenthyl chloride obtained from an Appel reaction led to p-menth-3-ene in excellent yield. Further functionalization of the double bond in p-menth-3-ene with chloramine-T gave the corresponding N-tosylaziridines, which upon reaction with sodium azide and subsequent reduction of the azide functional group, formed the 1,2-diamine system. The synthesized chiral ligands proved effective in the asymmetric transfer hydrogenation of aromatic ketones and an endocyclic imine.
Copper(I)-catalyzed boryl substitution of unactivated alkyl halides
Ito, Hajime,Kubota, Koji
scheme or table, p. 890 - 893 (2012/05/05)
Borylation of alkyl halides with diboron proceeded in the presence of a copper(I)/Xantphos catalyst and a stoichiometric amount of K(O-t-Bu) base. The boryl substitution proceeded with normal and secondary alkyl chlorides, bromides, and iodides, but alkyl sulfonates did not react. Menthyl halides afforded the corresponding borylation product with excellent diastereoselectivity, whereas (R)-2-bromo-5-phenylpentane gave a racemic product. Reaction with cyclopropylmethyl bromide resulted in ring-opening products, suggesting the reaction involves a radical pathway.
Clarification of the stereochemical course of nucleophilic substitution of arylsulfonate-based nucleophile assisting leaving groups
Braddock, D. Christopher,Pouwer, Rebecca H.,Burton, Jonathan W.,Broadwith, Phillip
experimental part, p. 6042 - 6049 (2009/12/24)
(Chemical Equation Presented) Secondary alcohols modified as tosylates, PEG-sulfonates, or quisylates undergo inversion of configuration at the reacting center when treated with lithium halide in acetone at reflux, where the PEG-sulfonates and quisylates are substantially more reactive. In sterically hindered cases, elimination is a competing process. In contrast, when treated with TiCl4, simple secondary sulfonates give chloride products with partial inversion of configuration. Any observed retention of configuration in a given alkyl sulfonate substrate under these conditions is likely due to neighboring group participation or diastereoselective attack on a carbocation (or ion pair) rather than an SNi mechanism.
Microwave-assisted ester formation using O-alkylisoureas: A convenient method for the synthesis of esters with inversion of configuration
Chighine, Alessandra,Crosignani, Stefano,Arnal, Marie-Claire,Bradley, Mark,Linclau, Bruno
experimental part, p. 4753 - 4762 (2009/10/17)
(Chemical Equation Presented) The formation of carboxylic esters via reaction of carboxylic acids with O-alkylisoureas proceeds in excellent yields with very short reaction times when conducted in a monomode microwave synthesizer. Efficient processes were
Synthesis of the promising chiral synthon isopropyl-4R-methyl-6- iodohexanoate from L-(-)-menthol
Ishmuratov,Yakovleva,Ganieva,Muslukhov,Tolstikov
, p. 41 - 44 (2007/10/03)
A synthesis of the promising optically pure synthon isopropyl-4R-methyl-6- iodohexanoate based on ozonolytic transformation of the product of regiospecific dehydratation of L-(-)-menthol, (R)-p-menth-3-ene, into 2,6R-dimethyl-8- hydroxyoctan-3-one was proposed. 2005 Springer Science+Business Media, Inc.
Synthesis and cycloaddition reactions of 1,1'-dimenthene
Fabris,Leoni,De Lucchi
, p. 1223 - 1226 (2007/10/03)
The synthesis of the hitherto unknown 1,1'-dimenthene 11 from menthone has been studied in detail. The most convenient procedure entails conversion of menthone 6 into its tosylhydrazone 7, Shapiro transformation into the iodide 9 and copper-mediated homoc
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
Cesium Carboxylates in Dimethylformamide. Reagents for Introduction of Hydroxyl Groups by Nucleophilic Substitution and for Inversion of Configuration of Secondary Alcohols
Kruizinga, Wim H.,Strijtveen, Bert,Kellogg, Richard M.
, p. 4321 - 4323 (2007/10/02)
Cesium carboxylates, in particular the propionates, in dimethylformamide solvent give clean SN2 substitutions on a variety of compounds.
