65184-67-0Relevant academic research and scientific papers
Crystallization of a racemate affords a P 21 chiral crystal structure: Asymmetric unit of two opposite handed molecules simulates achiral P 21/ n packing via pseudosymmetry
Steinberg, Avital,Ergaz, Itzhak,Toscano, Ruben Alfredo,Glaser, Robert
, p. 1262 - 1270 (2011)
A racemic mixture consisting of a secondary ammonium salt (±)-(1RS,3SR,4RS)-1-phenyl-cis-3,4-n-butano-5,6-dihydro-1H-2, 5-benzoxazocine hydrochloride (1) crystallized as a "false conglomerate" of crystals in the monoclinic system, Sohncke space group P21 with two molecules of opposite handedness in the asymmetric unit and at 295(2) K: a = 10.224(2) A, b = 13.969(2) A, c = 12.724(2) A, β = 98.996(2)°, V = 1794.9(5) A3, Z = 4, and Z′ = 2. The cis-3,4-n-butano-5,6-dihydro-1H-2,5-benzoxazocine fused-ring skeletons are approximately enantiotopic and exhibit pseudoinversion and pseudo-n-glide relationships. These noncrystallographic symmetries enable space filling in the chiral crystal structure to resemble that of a higher order achiral P21/n apparent space group (Z = 4, Z′ = 1). The secondary ammonium salt molecules crystallize in patterns influenced by a complex blend of N-H...Cl, C-H...Cl, C-H...O, and C-H...Ar interactions that seem to be responsible for different conformational twists of the phenyl rings in the structure. Avnir's CSM method was adapted for quantification of crystallographic pseudosymmetry. RmS(G) measurements of distortion from ideal G symmetries were developed for pure translation, screw rotation, and glide reflection, as well as point group symmetries. Low rmS(i) and rmS(n-glide) values show high fidelity for the emulation of P21/n space filling in crystalline 1.(Figure Presented)
Solution- and solid-state structures of N-desmethylnefopam hydrochloride, a metabolite of the analgesic drug
Glaser,Geresh,Blumenfeld,Donnell,Sugisaka,Drouin,Michel
, p. 276 - 281 (2007/10/02)
The solid-state structure of (±)-N-desmethylnefopam hydrochloride (1), a metabolite of the analgesic drug, was determined by single-crystal X-ray diffraction analysis. Compound 1 gave crystalline prisms belonging to the orthorhombic Pcab space group, and
A new asymmetric synthesis of (R)- and (S)-3-arylphthalides: Extremely high diastereoselective reaction of arylcarbaldehydes with chiral [2-(1,3-oxazolidin-2-yl)phenyl]titanium ate complexes
Takahashi,Tsubuki,Higashiyama
, p. 681 - 684 (2007/10/02)
Chiral [2-(1,3-oxazolidin-2-yl)phenyl]titanium ate complexes are prepared from the corresponding lithium complexes, and the extremely high diastereoselective reaction of arylcarbaldehydes with the chiral titanium ate complexes is performed. Then, optically pure (R)- and (S)-3-arylphthalides are synthesized in favorable yields and the chiral auxiliary reagents are recovered with no less of the optical purity.
Ortho Metalation Directed by α-Amino Alkoxides
Comins, Daniel L.,Brown, Jack D.
, p. 1078 - 1083 (2007/10/02)
The addition of aromatic aldehydes to certain lithium dialkylamides in benzene or tetrahydrofuran gave α-amino alkoxides which were ortho lithiated with excess n-butyllithium.Subsequent alkylation and hydrolysis provided ortho-substituted aromatic aldehydes via a one-pot reaction.The ortho metalation of α-amino alkoxides derived from 1- and 2-naphthaldehyde and various substituted benzaldehydes was examined.When N,N,N'-trimethylethylenediamine was used as the amine component of the α-amino alkoxide, metalation could be carried out at lower temperatures.This rate increase is due to an intramolecular TMEDA-like assisted metalation.The synthetic utility of this ortho metalation, including how varying the amine component of the α-amino alkoxide affects the regiochemistry and metalation rate, is discussed.
