Synthesis and chiroptical properties of some piperidin-2-ones

Abstract

The synthesis of optically pure (R)-(+)-4-isopropylpiperidin-2-one, (R)-(+)-4-isopropyl-4-methylpiperidin-2-one, and (R)-(+)-5-methyIpiperidin-2-one in high yields from monocyclic terpene percursors are described. The CD spectra of these compounds are reported, and the chiroptical properties of -lactams are examined in terms of current theories for the amide chromophore. It is concluded that slight, conformationally induced nonplanarity of the amide chromophore is responsible for the signs of the longest wavelength bands in the CD spectra of these and related compounds.

Chiral exploration of 6,12‐diphenyldibenzo[b,f][1,5]diazocine with stable conformation

“…The electric transition moment was 2.514 D, which was calculated by time‐dependent Density Functional Theory (TDDFT) at the B3LYP/6‐31G* level with the Gaussian09 software package . Owing to the polarizability sequences of N > C, the geometry of II ‐(+)‐ R ‐ 3 implies the left‐handed screwness (counterclockwise orientation) of the π – π * transition moments, in agreement with the observed negative CD signal (Figures ).…”

Cohalogenation of limonene, carvomenthene and related unsaturated monoterpenic alcohols

“…I 2 in the place of cupric acetate 5 . } was prepared in 98 % yield (> 99 % purity) by catalytic hydrogenation of (R)-limonene, as described by Jackman et al 33 Infrared (IR) spectra were recorded on a Perkin Elmer 1600 series FTIR (film in NaCl pellets). Analyses by HRGC were performed on a HP-5890-II gas chromatograph with FID by using a RTX-5 silica capillary column and H 2 (flowrate 50 cm/s) as carrier gas.…”

Regioselective Hydrogenations

“…Due to the low solubility of water in the fatty acid and its ester (Table 2) and the high hydrophilicity of the styrene-divinylbenzene resin, the conversion of acid needs a high excess of alcohol or acid to obtain to a high yield of ester. Here only 5-10% of fatty acid has to be converted [7,8]. Here only 5-10% of fatty acid has to be converted [7,8].…”

“…The first technical application of this catalysis was the conversion of free fatty acids in vegetable oil to methyl ester. Using 20 g of methanol and 100 g of oil per 150 mL of catalyst in a fixed bed with an LHSV of 0.8 h −1 , a conversion of 95% is possible [7]. Using 20 g of methanol and 100 g of oil per 150 mL of catalyst in a fixed bed with an LHSV of 0.8 h −1 , a conversion of 95% is possible [7].…”

“…This applies to the hydrogenation of limonene on Raney nickel, exhibiting 96% selectivity to carvomenthene (Scheme 6) [7]. This applies to the hydrogenation of limonene on Raney nickel, exhibiting 96% selectivity to carvomenthene (Scheme 6) [7].…”