New preparative and optical resolution method for β-lactams

Convenient synthesis of symmetrical diketosulfides from enolizable ketones using [hydroxy(tosyloxy)iodo]benzene and na2S ⋅ 9H2O

“…In spite of these quantitative vari- ations in the stoichiometry of Na 2 S · 9H 2 O, we noticed the formation of several side products and the desired product, that is PhCOCH 2 SCH 2 COPh 2a was obtained in poor (17%) yield. To circumvent this solubility problem of Na 2 S · 9H 2 O, we decided to carry the reaction of Na 2 S · 9H 2 O with in situ generated αtosyloxyacetophenone using the grinding technique, developed by Toda and coworkers in which many reactions can be conducted in high yields under solvent-free conditions just by grinding the reactants together [9]. Usually these reactions were carried out on a very small scale in an agate pestle and mortar.…”

Crystal structure of (1S,6S)-8-benzyl-7,9-dioxo-8-aza-2-azoniabicyclo[4,3,0]nonane (2S3S)-(-)-hydrogen tartrate dihydrate, (C4H5N2O10(C14H17O2) · 2H2O, a chiral inclusion

“…Inclusion crystallization has proven to be an effective method for the separation of structural isomers and resolution of optically active organic materials [1,2]. Many chiral organic compounds have been resolved with this method [3][4][5][6][7]. Rac-1 has been resolved effectively by crystalline complexation with (25,35)-tartaric acid.…”

Optical resolutions by inclusion complexation with a chiral host compound

“…Chromatography of the complex on silica gel using THF as a solvent gave (+)-114 of 100% ee (0.23 g, 77%). 45 Similar treatment of rac-115 with 15c gave optically pure (+)-105 in 63% yield. X-ray crystal structure of a 1:1 complex of 15c and (+)-115 has been studied.…”

“…X-ray crystal structure of a 1:1 complex of 15c and (+)-115 has been studied. 45 For optical resolution of sulfoxides, binaphthol host 14 was found to be very effective. For example, when a solution of 14b (3.0 g, 10.5 mmol) and rac-methyl m-methylphenyll sulfoxide (116c) (3.23 g, 21.0 mmol) in benzene-hexane (1:1, 20 ml) was kept at room temperature for 12 h, a 1:1 complex of 14b and (+)-116c was obtained, after one recrystallization from benzene, as colorless prisms (3.57 g, 77%, mp 152-154 °C), which upon chromatography on silica gel gave (+)-116c of 100% ee (77%) and recovered 14b (77%) in the yields indicated.…”

“…20 Although rac-methyl 2-aminophenylpropanoate (40) was also resolved efficiently by complex-ation with 9a to give (+)-40 of 100% ee in 40% yield, optical resolution of rac-ethyl 2-amino-2-phenylethanoate (41) gave very poor result (Table 2). Similar resolutions of hydroxycarboxylic acid esters such as methyl 3-hydroxybutanoate (42) and its derivatives (43)(44)(45) were successful ( Table 2). 20 In order to know the reason for the efficient chiral recognition ability between the host and guest molecules, X-ray crystal structure of the inclusion complex of 9a and (+)-42 was studied.…”