“…Ausbeute erhalten werden kann [19] [20]. Diese Variante der allylischen Oxydation envies sich als sicher (s. jedoch Fussnote 5 im exper.…”
Section: Modifiziertenunclassified
“…Diese von Gerlach et al [29] eingefiihrte Methode hat ihre hervorragende Eignung zur Racematspaltung von a-Hydroxycarbonyl-Verbindungen sowohl zu praparativen wie zu analytischen Zwecken bereits mehrfach bewiesen [19][20][21][24] [30-321. Das 3-Acetoxy-4-oxo-~-jonon (10) wurde unter striktem Sauerstoffausschluss bei -5" in Methanol mit 1 N NaOH zur entsprechenden Hydroxyverbindung 14 verseift, die sich in bis zu 85proz. Ausbeute kristallin fassen liess.…”
unclassified
“…-MS.: 206 (46, M + ) . 191(12), 163 (IOO), 150(20), 149(22) 135(25), 121 (47), 43 (87).1,70-2,lO (m, 2 H , 2H-C(2));1,81 (d, J -I , 3 H , H3C-C(S));2,15-2,85 (m, von 4-0xo-~-jonon-~-(athylena~etal)~) (8). -2.…”
Synthesis of Astaxanthin from β‐Ionone. I. A Route to the Enantiomeric C15‐Wittig Salts by Chemical and Microbial Resolution of (±)‐3‐Acetoxy‐4‐oxo‐β‐ionone
Racemic 3‐acetoxy‐4‐oxo‐β‐ionone (10) was synthesized from the industrially accessible intermediate β‐ionone (5). Resolution of 10 into its enantiomers was achieved via the corresponding diastereomeric camphanates and by microbial resolution. Site‐selective alkylation of racemic and of optically pure 3‐acyloxy‐4‐oxo‐β‐ionones with vinyl magnesium chloride at −70° furnished the corresponding 3‐acyloxy‐4‐oxo‐9‐vinyl‐β‐ionols which could be transformed to the Wittig salts 1, 3 and 4, respectively, following known procedures [1].
“…Ausbeute erhalten werden kann [19] [20]. Diese Variante der allylischen Oxydation envies sich als sicher (s. jedoch Fussnote 5 im exper.…”
Section: Modifiziertenunclassified
“…Diese von Gerlach et al [29] eingefiihrte Methode hat ihre hervorragende Eignung zur Racematspaltung von a-Hydroxycarbonyl-Verbindungen sowohl zu praparativen wie zu analytischen Zwecken bereits mehrfach bewiesen [19][20][21][24] [30-321. Das 3-Acetoxy-4-oxo-~-jonon (10) wurde unter striktem Sauerstoffausschluss bei -5" in Methanol mit 1 N NaOH zur entsprechenden Hydroxyverbindung 14 verseift, die sich in bis zu 85proz. Ausbeute kristallin fassen liess.…”
unclassified
“…-MS.: 206 (46, M + ) . 191(12), 163 (IOO), 150(20), 149(22) 135(25), 121 (47), 43 (87).1,70-2,lO (m, 2 H , 2H-C(2));1,81 (d, J -I , 3 H , H3C-C(S));2,15-2,85 (m, von 4-0xo-~-jonon-~-(athylena~etal)~) (8). -2.…”
Synthesis of Astaxanthin from β‐Ionone. I. A Route to the Enantiomeric C15‐Wittig Salts by Chemical and Microbial Resolution of (±)‐3‐Acetoxy‐4‐oxo‐β‐ionone
Racemic 3‐acetoxy‐4‐oxo‐β‐ionone (10) was synthesized from the industrially accessible intermediate β‐ionone (5). Resolution of 10 into its enantiomers was achieved via the corresponding diastereomeric camphanates and by microbial resolution. Site‐selective alkylation of racemic and of optically pure 3‐acyloxy‐4‐oxo‐β‐ionones with vinyl magnesium chloride at −70° furnished the corresponding 3‐acyloxy‐4‐oxo‐9‐vinyl‐β‐ionols which could be transformed to the Wittig salts 1, 3 and 4, respectively, following known procedures [1].
“…Eine Verlangerung der Kette der Aldehyde 10 und 13 um drei C-Atome gelang nach bekannten Methoden [12] [13]: eine Aldolkondensation von 10 mit Aceton (NaOCH3, RT., 24 Std. ) lieferte das (3R)-3-Hydroxy-P-ionon (11)*) [ 121 [13] [[a]g=-85,0° (c=0,5%, Dioxan; Lit.…”
unclassified
“…[13]: [a]g=-82" (Dioxan)], das ohne weitere Reinigung mit AcetanhydriaPyridin in die gut kristallisierende Verbindung 122)6)7)[12] [13] [Smp. 36-38'; [a]g=-58,O0 (c= 1%, Dioxan); Lit.…”
Synthesis of Optically Active Natural Carotenoids and Structurally Related Compounds. V. Synthesis of (3R, 3′R)‐, (3S, 3′S)‐ and (3R,3′S; meso)‐zeaxanthin by Asymmetric Hydroboration. A New Approach to Optically Active Carotenoid Building Units
The synthesis of (3R, 3′R)‐, (3S, 3′S)‐ and (3R,3′S; meso)‐zeaxanthin (1), (19) and (21) is reported utilizing asymmetric hydroboration as the key reaction. Thus, safranol isopropenylmethylether (4) is hydroborated with (+)‐ and (−)‐(IPC)2BH to give the optically pure key intermediates 5 and 7 resp., which are transformed into the above‐mentioned C40‐compounds.
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