A new enzymatic method for synthesis of enantiomerically enriched δ-hexadecalactone (3) based on the enzymatic kinetic resolution of N-methyl-5-acetoxyhexadecanamide (1) is described. A combination of lipase-catalyzed hydrolysis and amidation improved enantioselectivity. Lipase-catalyzed amidation was also investigated. Detailed screening of solvents and additive amines was performed. The addit...

Novel sulfamide-amine alcohol ligands were designed using a grafting strategy and synthesized from readily available starting materials via a simple, efficient method. The key features of these ligands for the asymmetric addition of diethylzinc to aldehydes included stability, enhanced effectiveness without using Ti(O(i)Pr)(4), suitability for a variety of aldehydes, the ability to operate at r...

Solutions with as little as 1% enantiomeric excess (ee) of D- or L-phenylalanine are amplified to 90% ee (a 95/5 ratio) by two successive evaporations to precipitate the racemate. Such a process on the prebiotic earth could lead to a mechanism by which meteoritic chiral alpha-alkyl amino acids could form solutions with high ee values that were needed for the beginning of biology.

Two optically active (100% enantiomeric excess) isomers of ofloxacin [(+/-)-ofloxacin; DL-8280; (+/-)-9-fluoro-2,3-dihydro-3-methyl-10-(4-methyl-1-piperazinyl)-7-oxo-7 H-pyrido[1,2,3-de] [1,4] benzoxazine-6-carboxylic acid] were prepared by use of their optically resolved synthetic intermediates. One of the isomers, (-)-ofloxacin, was 8 to 128 times more potent in inhibiting the multiplication ...

A palladium-catalyzed, atroposelective C-P coupling process has been developed for the asymmetric synthesis of QUINAP and its derivatives in high enantiomeric excess. Bromide, triflate (OTf) and 4-methanesulfonylbenzenesulfonate (OSs) precursors were studied, leading in the case of the triflate to a novel dynamic kinetic resolution involving isomerization of an arylpalladium intermediate. The o...

A series of optically active hypervalent iodine(III) reagents prepared from the corresponding (R)-2-(2-iodophenoxy)propanoate derivative was employed for the asymmetric dioxytosylation of styrene and its derivatives. The electrophilic addition of the hypervalent iodine(III) compound toward styrene proceeded with high enantioface selectivity to give 1-aryl-1,2-di(tosyloxy)ethane with an enantiom...

Optical sensors that respond to enantiomeric excess of chiral analytes are highly demanded in chirality related research fields and demonstrate their potential in many applications, for example, screening of asymmetric reaction products. Most sensors developed so far are small molecules. This Tutorial Review covers recent advances in chirality sensing systems that are different from the traditi...

We report the use of carbon-proton heteronuclear selective refocusing 2D NMR experiments dedicated to the spectral analysis of enantiomers dissolved in weakly ordering chiral liquid crystalline solvents. The method permits the extraction of carbon-proton residual dipolar couplings for each enantiomer from a complex or unresolved proton-coupled 13C spectral patterns. Illustrative examples are an...

The first example to couple aldehydes and 3-bromo-2-halopropenes in a catalytic asymmetric manner is reported. The coupling reaction is effected by the use of a chiral sulfonamide-Cr complex (prepared in situ from 1d, CrBr3, Fe(III) or from Co(II), Et3N, and Mn), TMSCl, and 2,6-lutidine. The method reported here is operationally simple and scalable, furnishing 3-halohomoallylic alcohols with a ...

We demonstrate chirality-induced three-wave mixing in the microwave regime, using rotational transitions in cold gas-phase samples of 1,2-propanediol and 1,3-butanediol. We show that bulk three-wave mixing, which can only be realized in a chiral environment, provides a sensitive, species-selective probe of enantiomeric excess and is applicable to a broad class of molecules. The doubly resonant ...