Jian-Nan Guo

Chirality at phosphorus in pentacoordinate spirophosphoranes: stereochemistry by X-ray structure and spectroscopic analysis

Two pairs of enantiomers of stable chiral pentacoordinate spirophosphoranes with two bonds from the amino and two bonds from the carboxyl groups of amino acids have been synthesized and analysed. The results show that differences in chirality at phosphorus are linked to distinct differences in physical properties.

Benzoylmethyl 4-chlorobenzoate

The asymmetric unit of the title compound, C15H11ClO3, contains three molecules, A, B, and C. Molecules A and B are aligned edge-to-face, whereas molecules B and C are aligned almost parallel to each other. The crystal structure displays C—H⋯π and π–π [centroid–centroid distances of 3.960 (4), 3.971 (4) and 3.971 (4) for molecules A, B and C, respectively] parallel-displaced interactions, and C—H⋯O hydrogen bonds.

Tris(dibenzoyl­methanido-κ2O,O′)[(6S,8S)-(+)-7,7-dimethyl-3-(2-pyrid­yl)-5,6,7,8-tetra­hydro-6,8-methano­isoquinoline-κ2N,N′]gadolinium(III)

In the title compound, [Tb(C15H11O2)3(C17H18N2)], the 7,7-dimethyl-3-(2-pyridyl)-5,6,7,8-tetrahydro-6,8-methanoisoquinoline (LRR) ligand coordinates to TbIII through the two N atoms of the heterocycle. The metal centre is also chelated by three deprotonated 1,3-diphenylpropane-1,3-dione (dbm) ligands, forming enantiomerically pure [Tb(dbm)3 LRR]. The TbIII atom is located in a distorted square antiprism of eight coordinating atoms (six O and two N atoms).

(1S,3S,4S)-tert-Butyl N-[1-benzyl-3-hydr­oxy-5-phenyl-4-(picolinamido)pent­yl]carbamate

The title compound, C29H35N3O4, was obtained by the reaction of (2S,4S,5S)-tert-butyl N-(4-amino-1-benzyl-3-hydroxy-5-phenylpentyl)carbamate and picolinic acid using oxalyl chloride as a chlorinating reagent to activate the carboxyl group. In the crystal structure there are two molecules in the asymmetric unit, which are aligned edge-to-face. In one molecule, the pyridyl ring forms a dihedral angle of 22.0 (1)° with the phenyl ring of the terminal benzyl group and 14.3 (1)° with the other phenyl ring; in the other molecule, the corresponding angles are 12.1 (1) and 10.6 (1)°, respectively. The packing is stabilized by intermolecular hydrogen bonds and C—H⋯π interactions.

(S)-5-Hexyl-1-[(S)-2-hydr-oxy-1-phenyl-ethyl]-4-meth-oxy-1H-pyrrol-2(5H)-one.

The title compound, C19H27NO3, was obtained by the reaction of (3S,7aR)-7a-hexyl-7-methoxy-3-phenyl-2,3-dihydropyrrolo[2,1-b]oxazol-5(7aH)-one and triethylsilane using titanium(IV) chloride as catalyst. In the molecule, the phenyl and dihydropyrrolone rings form a dihedral angle of 83.8 (1)°. O—H⋯O hydrogen-bonding interactions lead to the formation of a chain parallel to the a axis.

3',6'-Bis(diethyl-amino)-3H-spiro-[2-benzo-thio-phene-1,9'-xanthene]-3-thione.

The title compound, C28H30N2OS2, was obtained by thionation of 3′,6′-bis(diethylamino)-3H-spiro[isobenzofuran-1,9′-xanthene]-3-one with 2,4-bis(p-methoxyphenyl)-1,3-dithiadiphosphetane disulfide (Lawesson’s reagent). The planes of the two benzene rings of the xanthene system are inclined at a dihedral angle of 17.4 (1)°, and the plane of the dithiophthalide group and the planes through the two benzene rings of the xanthene system make dihedral angles of 80.2 (1) and 82.8 (1)°, respectively.

(S)-1,5-Dibenzyl-3-tert-butyl­imidazol­idin-4-one

The title compound, C21H26N2O, was obtained as an unexpected by-product when attempting to prepare (S)-2-benzyl-N-tert-butyl-1,2,3,4-tetrahydroisoquinoline-3-carboxamide from (S)-2-benzylamino-N-tert-butyl-3-phenylpropanamide and dimethoxymethane. The molecules are linked by weak C—H⋯O hydrogen bonds, generating linear chains parallel to the b axis. C—H⋯π interactions provide further stability for the crystal structure. The planes of the two phenyl rings make a dihedral angle of 84.1 (1)°. The absolute configuration was known from the starting material.

(4S)-Benzyl 4-isopropyl-5-oxo-1,3-oxazolidine-3-carboxyl-ate.

In the crystal structure of the title compound, C14H17NO4, obtained by the reaction of N-benzoxycarbonyl-l-valine, paraformaldehyde and 4-methylbenzenesulfonic acid, molecules are linked by C—H⋯O hydrogen bonds, generating linear chains parallel to the a axis. C—H⋯π interactions of stacked benzene rings also provide stability for the crystal structure.

Benzoyl-methyl pyridine-4-carboxyl-ate.

In the crystal structure of the title compound, C14H11NO3, isolated from the reaction of 2-bromo-1-phenylethanone and pyridine-4-carboxylic acid using triethylamine as a base to deprotonate the organic acid, the molecular packing is stabilized by C—H⋯π interactions involving the phenyl and pyridine rings. The C—C—O—C torsion angle for the linkage between the two carbonyl groups is −80.8 (2)°, and the planes of the phenyl and pyridyl rings form a dihedral angle of 65.8 (1)°.