Rhodium chiral monophosphine complex catalyzed hydrogenations of terpenic and .alpha.-(acylamino)-substituted acrylic acids

Chiral trans-1,2-diaminocyclohexane derivatives as chiral solvating agents for carboxylic acids

“…We have chosen the chiral diamines (1-2) and macrocyclic amines (3)(4)(5) to examine their chiral recog- nition ability towards mandelic acid 6 and 2,3-diphenylsuccinic acid 7 and N-Ts-phenylglycine 8 by 1 H-NMR spectroscopy. The chiral diamines 1 and 2 were readily synthesized by reductive Nalkylation of (R,R)-trans-1,2-diaminocyclohexane with corresponding prochiral ketones in this laboratory 20 (1).…”

“…In view of the importance of chiral organic compounds in biological and pharmaceutical chemistry, [1][2][3][4] there is increasing requirement for fast and accurate methodologies for the determination of enantiomeric composition of these chiral compounds. Among the various available methods, NMR spectroscopy has the advantages of easy performance and accessibility 5 with no need for special equipment apart from the common NMR spectrometers.…”

The Diastereoselective Formation of Tetraalkoxy[4]resorcinarenes Derived from (–)‐(2R)‐2‐Methoxy‐2‐phenylethanol and Proof of Absolute Configurations

“…[16,21] To establish the absolute configurations of the diastereoisomers 6a and 6b it was necessary to prepare compounds 11 and 12, with known absolute configurations, by alkylating the enantiomerically pure tetramethoxyresorcin[4]arenes (-)-(M,R)-8 and (+)-(P,S)-8, derived from 3-methoxyphenol and hexanal, which we had prepared and fully characterized previously, and to compare these compounds with those prepared by the methylation of 6a and 6b. [22] We chose to optimize the alkylation of the racemic tetramethoxyresorcin[4]-arene (Ϯ)-8 using the mesylate 9 and tosylate 10 (the enantiomer of which has been reported previously) [23] prepared in 87 and 75 % yields, respectively, from (-)-(2R)-2-methoxy-2-phenylethanol (2), as shown in Scheme 3. A series of experiments showed that alkylation of the racemic tetramethoxyresorcin[4]arene (Ϯ)-8 using tosylate 10 gave slightly higher yields of the diastereoisomers 11 and 12 than when mesylate 9 was used.…”

“…The organic phase was dried with anhydrous sodium sulfate and concentrated under reduced pressure. The residue was placed on a column of silica gel and eluted with ethyl acetate/hexane (3:7) to give 9 as a yellow oil (1.3 g, 87 % (2R)-2-Methoxy-2-phenylethyl p-Toluenesulfonate (10): [23] (2R)-2-Methoxy-2-phenylethanol (45; 1 g, 6.6 mmol, 1 equiv. ), triethylamine (1.3 g, 13.2 mmol, 2 equiv.)…”

Enantioselektive Katalyse, 121. Mitt. [1]: Chirale Phosphanliganden mit zusätzlichen Sauerstoffunktionalitäten

“…Die Synthese von 14 ging von 1, aus, das durch asymmetrische Dihydroxylierung von E-Stilben mit hoher optischer und chemischer Ausbeute erha Èltlich ist [9] Die Synthese von (1S)-1-Diphenylphosphanyl-1-phenyl-3-oxobutan (24) wurde durch die Bedeutung der verwandten Verbindung 2-Phenyl-2-diphenylphosphanylmethoxyethan [17] angeregt. Die Reaktion des (R)-kon®gurierten Alkohols 6 wurde in Pyridin als Solvens und Base mit p-Toluolsulfonsa Èurechlorid bei 0 C durchgefu Èhrt [17,18]. Die Aufarbeitung erfolgte durch Abdestillieren des Pyridins und anschlieûende Sa Èulenchromatographie.…”