Solid state stereochemistry of crown ethers: X-ray crystal structure and ¹³C NMR studies of the LiNCS complex of 1,4,7,11-tetraoxacyclotetradecane

Abstract

The title complex is asymmetric in the crystal due to the spatial orientation of the NCS function. The space group has been determined to be P2 1 with a = 9.496(3), b = 8.736(3), c = 9.676(3) D, β = 117.859(5)°, and Z = 2. The solid state 13 C NMR spectrum is consistent with the lack of symmetry in the crystal and there is little evidence for large amplitude motion in the macrocycle as determined from the dipolar dephased spectrum.Résumé : À l'état cristallin, le complexe mentionné dans le titre est asymétrique en raison de l'orientation spatiale de la fonction NCS. On a déterminé que le groupe d'espace est P2 1 avec a = 9,496 (3), b = 8,736(3) et c = 9676(3) D, β = 117,859(5)°et Z = 2. Le spectre RMN du 13 C à l'état solide est en accord avec un manque de symétrie dans le cristal et, sur la base du spectre déphasé dipolaire, il y a peu d'indications pouvant suggérer l'existence d'un mouvement de grande amplitude dans le macrocycle. Mots clés : éther couronne macrocyclique, complexe de lithium. [Traduit par la Rédaction] Buchanan et al. 321

Long Hydrocarbon Chain Ether Diols and Ether Diacids That Favorably Alter Lipid Disorders in Vivo

“…2 However, the yield for this reaction was only 13%, and purification of 4 was difficult (fractional distillation). A better overall yield (36%) was obtained when dinitrile 2 was converted via a three-step reaction sequence consisting of saponification (concentrated HCl), 3 esterification (EtOH, concen-trated H 2 SO 4 ), 4 and reduction (LiAlH 4 ) to diol 3 (66%), 4 which was then transformed to 4 with PBr 3 (55%). 5 Bromide substitution in 4 with lithio ethyl isobutyrate and lithio ethyl 2-phenylpropionate 1,6 in THF and cosolvent dimethylpropyleneurea (DMPU) gave diesters of the esters with LiAlH 4 afforded ether diols 9 7 and 10 (79% and 82%) after purification by distillation or chromatography.…”

Preparation of Discrete Oligoethers: Synthesis of Pentabutylene Glycol and Hexapropylene Glycol by Two Complementary Methods

“…Flash chromatography on silica gel (1:10 EtOAc/hexane) afforded 480 mg (76%) of the triether product as a colorless oil: TLC Rf ) 0.65 (1:4 EtOAc/ hexane); 1 H NMR (CDCl3, 400 MHz) δ 7.24-7.36 (m, 10 H), 4.50 (s, 4H), 3.55 (t, 4H, J ) 6.4 Hz), 3.52 (t, 4H, J ) 6.4 Hz), 1.87 (app qn, 4H, J ) 6.4 Hz); 13 Ether Diol 7. 9 To a solution of 1-benzyloxy-3-(3-benzyloxypropoxy) propane (456 mg, 1.45 mmol, 1 equiv) in MeOH (20 mL) was added Pd/C (200 mg, 10 wt % Pd). The atmosphere was replaced with H2, and the mixture was stirred under 1 atm H2 for 5 h. The Pd/C was filtered off, and the filtrate was concentrated in vacuo.…”