Characteristic conformation of Mosher's amide elucidated using the cambridge structural database.

Conformations of the crystalline 3,3,3-trifluoro-2-methoxy-2-phenylpropanamide derivatives (MTPA amides) deposited in the Cambridge Structural Database (CSD) were examined statistically as Racid-enantiomers. The majority of dihedral angles (48/58, ca. 83%) of the amide carbonyl groups and the trifluoromethyl groups ranged from -30° to 0° with an average angle θ1 of -13°.

Expressional and functional analysis of CYP15A1, a juvenile hormone epoxidase, in the red flour beetle Tribolium castaneum.

Juvenile hormone (JH) is synthesized and secreted by the corpora allata. In the final two steps of JH biosynthesis, farnesoic acid (FA) is converted to JH through methylation by JH acid O-methyltransferase (JHAMT) and epoxidation by the cytochrome P450 enzyme CYP15. In the present study, we identified a homolog of CYP15 from the red flour beetle Tribolium castaneum (TcCYP15A1), and analyzed its expression as well as its role in JH biosynthesis.

Naphthyl groups in chiral recognition: structures of salts and esters of 2-methoxy-2-naphthylpropanoic acids.

The crystal structures of salt 8, which was prepared from (R)-2-methoxy-2-(2-naphthyl)propanoic acid ((R)-MβNP acid, (R)-2) and (R)-1-phenylethylamine ((R)-PEA, (R)-6), and salt 9, which was prepared from (R)-2-methoxy-2-(1-naphthyl)propanoic acid ((R)-MαNP acid, (R)-1) and (R)-1-(p-tolyl)ethylamine ((R)-TEA, (R)-7), were determined by X-ray crystallography. The MβNP and MαNP anions formed ion-pairs with the PEA and TEA cations, respectively, through a methoxy-group-assisted salt bridge and aromatic CH⋅⋅⋅π interactions. The networks of salt bridges formed 2(1) columns in both salts.

First preparation of single-enantiomer juvenile hormone III acid and (R)-juvenile hormone III-d₃.

The (R)- and (S)-enantiomers of juvenile hormone (JH) III acid [(R)-2 and (S)-2] were prepared by the hydrolysis of (R)- and (S)-JH III [(R)-1 and (S)-1], respectively. Each enantiomer of 2 was purified by preparative reversed-phase high performance liquid chromatography in a single operation. (RS)-2 was methylated with CH₃I and K₂CO₃ in MeCN, yielding (RS)-1.

Preparation of single-enantiomer biofunctional molecules with (S)-2-methoxy-2-(1-naphthyl)propanoic acid.

(RS)-beta-Ionol and (RS)-2-methyl-4-octanol were resolved by using (S)-2-methoxy-2-(1-naphthyl)propanoic acid [(S)-MalphaNP acid]. The specific stereochemistry of each MalphaNP ester was elucidated by 2D NMR analyses, and shielding by the 1-naphthyl group was observed in both the 1H- and 13C-NMR spectra. Solvolysis of the individual (S)-MalphaNP esters gave four single-enantiomer alcohols.

Enantioselective separation of racemic juvenile hormone III by normal-phase high-performance liquid chromatography and preparation of [(2)H(3)]juvenile hormone III as an internal standard for liquid chromatography-mass spectrometry quantification.

Juvenile hormone III (JH III) racemate was prepared from methyl (2E,6E)-farnesoate via epoxidation with 3-chloroperbenzoic acid (mCPBA). Enantioselective separation of JH III was conducted using normal-phase high-performance liquid chromatography (HPLC) on a chiral stationary phase. [(2)H(3)]Methyl (2E,6E)-farnesoate was also prepared from (2E,6E)-farnesoic acid and [(2)H(4)]methanol (methanol-d(4)) using 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDC) and 4-dimethylaminopyridine (DMAP); the conjugated double bond underwent isomerization to some degree.

Preparation of single-enantiomer 2-methyl-4-heptanol, a pheromone of Metamasius hemipterus, using (S)-2-methoxy-2-(1-naphthyl)propionic acid.

To investigate the resolution of secondary alcohols using 2-methoxy-2-(1-naphthyl)propionic acid (MalphaNP acid), 2-methyl-4-heptanol, one of the aggregation pheromones of Metamasius hemipterus, was resolved using (S)-MalphaNP acid. As a chiral-resolving agent, MalphaNP acid is superior to 3,3,3-trifluoro-2-methoxy-2-phenylpropionic acid (MTPA) in terms of HPLC separation and NMR shielding. A better separation of diastereomeric MalphaNP esters was observed when n-hexane-THF was used as the eluent for silica gel HPLC.

MalphaNP acid, a powerful chiral molecular tool for preparation of enantiopure alcohols by resolution and determination of their absolute configurations by the (1)H NMR anisotropy method.

A novel methodology using a chiral molecular tool of MalphaNP acid (1), 2-methoxy-2-(1-naphthyl)propionic acid, useful for preparation of enantiopure secondary alcohols and determination of their absolute configurations by the (1)H NMR anisotropy method was developed; racemic MalphaNP acid (1) was enantioresolved with (-)-menthol, and the enantiopure MalphaNP acid (S)-(+)-(1) obtained was allowed to react with racemic alcohol, yielding a mixture of diastereomeric esters, which was clearly separated by HPLC on silica gel. By applying the sector rule of (1)H NMR anisotropy effect, the absolute configuration of the first-eluted MalphaNP ester was unambiguously determined. Solvolysis or reduction of the first-eluted MalphaNP esters yielded enantiopure alcohols.

Stereochemical studies of chiral resolving agents, M9PP and H9PP acids.

The stereoselective Grignard reaction of (1R,2S,5R)-(-)-2-isopropyl-5-methylcyclohexyl pyruvate (menthyl pyruvate) with 9-phenanthrylmagnesium bromide yielded diastereomeric hydroxy-esters, where intramolecular OH em leader O=C hydrogen bond was observed in IR and (1)H NMR spectra. The alkaline hydrolysis of the major product gave (+)-2-hydroxy-2-(9-phenanthryl)propionic acid (H9PP acid (3)), whose absolute configuration was assigned as S based on the chemical correlation with (1R,2S,5R)-2-isopropyl-5-methylcyclohexyl ester of (S)-2-methoxy-2-(9-phenanthryl)propionic acid (M9PP acid (2)); the absolute configuration of 2 had been previously established by X-ray crystallography. The enantioresolution of (+/-)-6-methyl-5-hepten-2-ol, sulcatol, an insect pheromone, was carried out using (S)-(+)-M9PP acid 2.

Practical enantioresolution of alcohols with 2-methoxy-2-(1-naphthyl)propionic acid and determination of their absolute configurations by the (1)H NMR anisotropy method.

The enantioresolution of racemic alcohols as esters of 2-methoxy-2-(1-naphthyl)propionic acid (MalphaNP acid 1) and the determination of their absolute configurations on the basis of (1)H NMR anisotropy effect are described. The enantiopure MalphaNP acid (S)-(+)-1 was allowed to react with racemic 2-alkanols and 1-octyn-3-ol, yielding diastereomeric mixtures of esters, which were easily separated by HPLC on silica gel. To determine the absolute configurations of the first-eluted diastereomeric esters by the (1)H NMR anisotropy method, the general scheme was proposed.

Absolute Configurations of Some Hydroxy-fatty Acids Produced by the Insect Genus Laccifer.

The absolute configurations of some hydroxy-fatty acids were examined by the modified Mosher's method proposed by Ohtani et al. The absolute configurations of the major components were determined from NMR data of their ΜΤΡΑ esters and 2-ΝΜΑ esters. The application of Mosher's method for the anti-glycol is discussed.