10.1055/s-1998-1891
The research presents a novel and general synthetic approach to the asymmetric synthesis of enantiopure α-amino ketones and syn-β-amino alcohols, which are key components of bio-active molecules. The study employs α-amino alkyllithiums, generated via an improved version of Pearson's transmetalative protocol, as key synthetic intermediates. The purpose of this research was to overcome the challenges associated with the enantioselective generation and configurational instability of α-amino organolithiums, which had limited the exploration of this synthetic route. The researchers successfully developed a more convenient and flexible route to the requisite stannane, and demonstrated the synthetic potential of this method in the context of the asymmetric synthesis of syn-β-amino α-trifluoromethyl alcohol, a candidate for protease inhibitor. The chemicals used in the process include α-hydroxy stannane, potassium salt of (S)-4-phenyl-2-oxazolidinone, n-BuLi, aldehydes, Dess-Martin periodinane, L-Selectride, and benzyloxycarbonyl chloride, among others. The conclusions of the research indicate the development of an efficient and flexible synthetic route to enantiopure α-amino ketones and syn-α-amino alcohols, with ongoing work to expand the synthetic scope of this methodology.
10.1021/jo801580g
The study, titled "Oxidative Conversion of r,r-Disubstituted Acetamides to Corresponding One-Carbon-Shorter Ketones Using Hypervalent Iodine (λ5) Reagents in Combination with Tetraethylammonium Bromide," investigates a novel method for converting R,R-disubstituted acetamides into ketones that are one carbon atom shorter. The key chemicals involved are hypervalent iodine (λ5) reagents, specifically o-iodoxybenzoic acid (IBX) and Dess-Martin periodinane (DMP), and tetraethylammonium bromide (TEAB). These reagents are used to oxidatively dehomologate R,R-disubstituted acetamides, resulting in the formation of ketones. The study establishes a mild, efficient, and general method for this transformation, with IBX and TEAB in acetonitrile at 60 °C yielding the best results. The researchers also explored the reaction mechanism, proposing that an N-bromoimine intermediate forms during the process, which subsequently hydrolyzes to produce the ketone.
10.1055/s-0037-1610752
Shuai Wang and George A. Kraus present a novel synthetic route to pogopyrone A using dehydroacetic acid. The authors converted dehydroacetic acid into silyl enol ether and titanium enolate, which reacted efficiently with aldehydes and N-bromosuccinimide. The key step involved the oxidation of the adduct with benzaldehyde using Dess–Martin periodinane (DMP), yielding pogopyrone A with a 78% yield. The study also explored the reactivity of these intermediates with various aldehydes, achieving good yields and scalability. The titanium enolate method was particularly effective, allowing for the synthesis of pogopyrone A in excellent overall yield. The work provides a direct and efficient synthesis of pogopyrone A, contributing to the field of organic synthesis and natural product chemistry.
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