Abstract:E n a n t i o m e r i c a l l y P u r e M e n t h y l a m i n e s a n d T h e i r I s o c y a n a t e s Abstract: A synthetic protocol for optically pure (-)-menthylamine, (-)-8-methylmenthylamine, and the novel (-)-8-phenylmenthylamine is presented including a detailed characterization of these compounds and their isocyanates.Enantiomerically pure a-chiral amines 1 are important building blocks and auxiliaries in synthetic organic chemistry. 1 Several methodologies are established for the enantioselective syn… Show more
p‐Toluenesulfonyl (Tosyl) and nitrobenzenesulfonyl (Nosyl) are two of the most common sulfonyl protecting groups for amines in contemporary organic synthesis. While p‐toluenesulfonamides are known for their high stability/robustness, their use in multistep synthesis is plagued by difficult removal. Nitrobenzenesulfonamides, on the other hand, are easily cleaved but display limited stability to various reaction conditions. In an effort to resolve this predicament, we herein present a new sulfonamide protecting group, which we term Nms. Initially developed through in silico studies, Nms‐amides overcome these previous limitations and leave no room for compromise. We have investigated the incorporation, robustness and cleavability of this group and found it to be superior to traditional sulfonamide protecting groups in a broad range of case studies.
p‐Toluenesulfonyl (Tosyl) and nitrobenzenesulfonyl (Nosyl) are two of the most common sulfonyl protecting groups for amines in contemporary organic synthesis. While p‐toluenesulfonamides are known for their high stability/robustness, their use in multistep synthesis is plagued by difficult removal. Nitrobenzenesulfonamides, on the other hand, are easily cleaved but display limited stability to various reaction conditions. In an effort to resolve this predicament, we herein present a new sulfonamide protecting group, which we term Nms. Initially developed through in silico studies, Nms‐amides overcome these previous limitations and leave no room for compromise. We have investigated the incorporation, robustness and cleavability of this group and found it to be superior to traditional sulfonamide protecting groups in a broad range of case studies.
“…Currently, all the synthetic pathways of (+)-neomenthylamine rely on chemical methods with terpenoids initial reactants such as (−)-menthone (Wallach 1891;Kozlov et al 1981;Kozlov 1982;Schopohl et al 2003). A conventional way was to convert (−)-menthone by reductive amination under Leuckart-Wallach conditions (Kitamura et al 2002), which could obtain all the neomenthylamines isomers.…”
Section: Introductionmentioning
confidence: 99%
“…Subsequently, dielectrically controlled resolution (DCR) of racemic neomenthol by (R, R)-tartaric acid and electrochemical synthesis with mercury pool cathode were both used to produce optical pure (+)-neomenthylamine stereoselectively (Schopohl et al 2003;Kulisch et al 2011;Schmitt et al 2014;Reinscheid and Reinscheid 2016). In recent reports, hydrogenation of menthone oxime to amines via gold catalysts has excellent yields in high temperature.…”
(+)-Neomenthylamine is an important industrial precursor used to synthesize high value-added chemicals. Here, we report a novel biocatalytic route to synthesize (+)- neomenthylamine by amination of readily available (−)-menthone substrate using ω-transaminase. By screening a panel of ω-transaminases, an ω-transaminase from Vibrio fluvialis JS17 was identified with considerable amination activity to (−)-menthone, and then characterization of enzymatic properties was conducted for the enzyme. Under optimized conditions, 10 mM (−)-menthone was transformed in a mild aqueous phase with 4.7 mM product yielded in 24 h. All raw materials were cheap and by-products were easily removed. This method underscores the potential of biocatalysts in the synthesis of unnatural terpenoid amine derivatives.
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