Chiral recognition in clefts and cyclophane cavities shaped by the 1,1'-binaphthyl major groove

Abstract

5835from Os04, lb, and stilbene in toluene was determined by X-ray crystallographic analysis (Figure l ) . 8 3 9The stable octahedral complex 2 is free of toluene, and the diamine lb is chelating to osmium as clearly indicated by their N-.Os distances (2.16 and 2.22 A), which are very close to those reported for the pyridinelO and the quinuclidine'l osmate complexes. Each osmate phenyl group is facing a bulky neohexyl substituent of lb. This is very similar to the stereostructure of the corresponding osmate ester-(8) After the 1:l:l mixture was stirred at -78 OC for 12 h, the volatiles were removed in vacuo and the resultant dark brown slurry was purified on silica, recrystallized from hexane-CHzC!z to give 2 as brown needles: mp 180 "C dec. Crystal data: orthorhombic crystals, P212121, with a = 25.92 A, b = 12.16 A, c = 10.57 A, (Y = 6 = y = 90.0°, 2 = 4, V = 3328 A3, Dd = 1.49 g ~m -~, final R value = 0.066 for 2879 reflections (Rigaku (9) Oxidative hydrolysis of the isolated 2 with N-methylmorpholine N-oxide in aqueous acetone turned out to be too slow in accordance with Sharpless' findings for chelating ligands.& (10) Conn, J. F.; Kim, J. J.; Suddath, F. L.; Blattmann, P.; Rich, A. J. Am. Chem. SOC. 1974, 96, 7152. (11) Cartwright, B. A.; Griffith, W. P.; Schroder, M.; Skapski, A. C. J. Chem. SOC., Chem. Commun. 1978, 853. AFC5-R, Mo-Ka).Figure 1. ORTEP drawing of 2. diamine complex reported by Tomioka and Koga et al.ldThe study of the structure of the complex of lb and Os04 is currently underway. The detailed mechanisms for the asymmetric osmylation will be discussed in due course.

Studies of vitamin D (calciferol) and its analogs. 42. 3-Deoxy-3-thia-1.alpha.,25-dihydroxyvitamin D3 and its 1.beta.-epimer: synthesis and biological evaluation

“…The synthesis of the A-ring fragment began with the coupling of bromomethyl ethyl ketone 14 and thioglycolate 15 to afford keto ester 16 (Scheme II).11 The latter underwent an intramolecular cyclization to produce thia 1,3-diketone 13 using sodium hydride to generate the (5) (a) Barrack, S. A.; Gibbs, R. A.; Okamura, W. H. J. Org. Chem. 1988Chem.…”

Chiral 1,1′‐Binaphthyl Molecular Clefts for the Complexation of Excitatory Amino‐Acid Derivatives

“…Scheme After introduction of solubilizing dodecyl chains, the tetraether 22 was metalated with BuLi and reacted with CO, [20a] to give the dicarboxylic acid 23. Amination with 6-methylpyridin-2-amine led to 24 which was debenzylated [26] to the 7,7'-diol 25 and subsequently methylated [27] to give 26.…”

“…Although high binding affinity is not synonymous to high enantioselection [~OC], many examples in the host-guest complexation studies by Cram and Cram showed a correlation between the two quantities [3a]. For the optical resolution of diol(&)-21 as a precursor to the two type-B receptors, procedures [26] [37] previously applied to the resolution of 1, I'-binaphthyl-2,2'-diols [38] were followed. The cyclic phosphate (f- a ) 1) POCl,, NEt,, CH,Cl,; 2) THF, H,O, A ; 96%.…”

“…d ) 1) 6~ aq. HCl, EtOH, A then r.t.; 2) Me2S0,, NaHCO,, DMA; 3) LiAlH,, THF, 0"; 78% of (S)-21 and 67% of (R)-21, based on 'H-NMR spectra, which is indicative of distinctively different solution geometries and presumably also stabilities [26]. In a 1.0 m~ solution, well separated singlets of receptor protons were observed for the two diastereoisomeric complexes at 6.55 and 6.60 ppm (H-C (8)) and at 8.08 and 8.10 ppm (H-C(5)).…”

“…was filtered through a plug of Celite, the plug washed with hot AcOEt, and the filtrate evaporated: 25 (87.6 mg, 95% 46,H 8.08,N 6.07,0 10.40;found: C 75.54,H 8.25,N 5.88,O 10.66. 2, -I .l'-binuphthyl-6,6'-dicurbo~u~ide (26).…”