1993
DOI: 10.1002/cber.19931260630
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2,6‐Dicyan‐4,8‐diphenylbarbaralan

Abstract: 2,6‐Dicyano‐4,8‐diphenylbarbaralane[1] Conjugate addition of the phenylcuprate reagent, obtained from phenyllithium, copper(I) cyanide, and boron trifluoride–diethylether, to the bicyclo[3.3.1]nonadienedione 3 affords the diphenylbicyclo[3.3.1]nonanedione 4 in high yield. Catalyzed by the potassium cyanide/18‐crown‐6 complex, addition of trimethylsilyl cyanide produces a mixture of the diastereomeric bis[O‐(trimethylsilyl)cyanohydrins] exo,exo‐, exo,endo‐ and endo,endo‐5. The hydrogen fluoride – pyridine compl… Show more

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Cited by 24 publications
(20 citation statements)
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“…, which was estimated on the basis of chemical shifts in the 13 C NMR spectra. [21] The temperature dependence of the fractions f* that exist in the higher state A* was calculated from Equations (2) and (4) and is displayed in Figure 4.…”
mentioning
confidence: 99%
See 1 more Smart Citation
“…, which was estimated on the basis of chemical shifts in the 13 C NMR spectra. [21] The temperature dependence of the fractions f* that exist in the higher state A* was calculated from Equations (2) and (4) and is displayed in Figure 4.…”
mentioning
confidence: 99%
“…[26] Only in the case of 1 a can the enthalpy difference DH 0 between A, A' ' and A* be compared with the barrier for the degenerate Cope rearrangement A > A' ', DG = (200 K) 14.4 kJ mol À1 (in chlorodifluoromethane/ [D 6 ]dimethyl ether). [27] Those barriers are too low to be determined by 13 C NMR spectroscopy for the other compounds, and any estimates based on increments for substituents [27] must assume their additivity, which can hardly be justified. Nevertheless, qualitative arguments on the basis of cooperative steric and electronic substituent effects, and constant solvation terms support the conclusion that the DH 0 values roughly parallel the heights of the Cope barriers.…”
mentioning
confidence: 99%
“…Unfortunately, a preparative column of this sort was unavailable, and attempts at separation on normal silica-gel 50Ϫ60% on a 0.1 mole scale [13] [14] and lies already halfway on the route to rac-1. Exploratory experiments with the columns met with failure.…”
Section: Resultsmentioning
confidence: 99%
“…Distillation of the solvent in vacuo yielded a pale yellow oil. Cyclic MPLC on silica gel with PE/EA {80:20, 50 ml/min, 12 bar, 2 cycles, tR [min]: 15 (26) and 20 (25) I,3-Diphenyl-3-[(2,4-diphenyl)phenyl]-2-propen-I-one (22): A vigorously stirred emulsion of 26 (30 mg, 0.06 mmol) in hydrochloric acid (6 M, 2 ml) was heated under reflux for I h. After cooling to 20-25"C, the deep yellow emulsion was extracted with diethyl ether (2 X 5 ml). The organic layer was extracted with a sat.…”
Section: Full Papermentioning
confidence: 99%