Carotinoidsynthesen über Sulfone; Synthese von β‐Carotin

Fischli, Albert; Mayer, H.

doi:10.1002/hlca.19750580611

Cited by 23 publications

(16 citation statements)

References 11 publications

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“…The optically active (2R,3S)-2,3-epoxy alcohol (1) was obtained from S-phenyl-2-penten-l-o1 [9] in 94% enatiomeric excess by the Sharpless asymmetric epoxidation using (+)-diethy1 tartrate [l]. It was treated with NaH in a mixture of carbon disulfide and THF (1 : 1-3) at -78"C, and then the mixture was warmed gradually to -30°C to give [4R,( 1 'S)]-4 4 1 -hydroxy-3-phenylpropyl]-1,3-oxathiolane-2thione (2) in 83% yield.…”

Section: Intvarnolecular Stereospecific Ring Opening Of a 23-epoxy Amentioning

confidence: 99%

Intramolecular ring opening of a 2,3‐epoxy alcohol by a xanthate anionic center; stereospecific preparation of 2‐mercapto‐1,3‐diol units

Uenishi

Motoyama

Nishiyama

et al. 1994

Heteroatom Chemistry

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Section: Intvarnolecular Stereospecific Ring Opening Of a 23-epoxy Amentioning

confidence: 99%

Intramolecular ring opening of a 2,3‐epoxy alcohol by a xanthate anionic center; stereospecific preparation of 2‐mercapto‐1,3‐diol units

Uenishi

Motoyama

Nishiyama

et al. 1994

Heteroatom Chemistry

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“…: C 53,10, H 5.98, N 40,84. (2)). 13C-NMR (25.2 MHz): 22,0,22,4 (24,2 CH,);24,9,41,8 (2d,2 CH); 44,3 (t. CH,); 122,6 (s, CN). MS: 165 (23, M" -HCN -CH, des Iminobis(nitrils)), 112 (28, M+' von 14), 11 1 (55), 109 (37), 57 (100).…”

Section: Vergleich Der Retentionszriten Im Hplc Der Uroporphyrinogeunclassified

“…"C-NMR ((D,)Aceton, 7S,47 MHz): 14,33 (r, 2 118,65, 120,03, 120.58 (3s, 3 CN); 130,74 (d, C (6) (4)); 3,14 (d,J = 0,9,CHJ;3.63,3,73 (AB, J = 17,4, CH,); 3.98 (dd, J = 7,9,6,8,CH (2)); 4.06 (s, CHI); 6,24 CH2); 20,85, 27,88, 29,94, 41,39, 46,lO (5t, 5 CH2); 59,13, 75,51 (2d, 2 CH); 101,24 (s, C(5)); 118,03 (s, 2 CN); H-CH); 2,09-2,41 (m, CH2, H-CH); 2,54-2,76 (m, 2 CH,); 3,34 (dd, J 10,2,3,CH(4)); 3,36 (s, CH,); 3,46,3,92 (AB, J = 17,6, CH,); 4,08 (dd, J = 10,6,4,9,CH(2)); 4,23 4,31 (AB, J = 18,3, CH,); 6,36 (dd, J = 2,3, 1,1, CH (6)). I3C-NMR((D,)Aceton, 75,47 MHz): 13,79,14,14,20,50,24,76,30,10,36,45. 39,76(7t,7 CH,);60,50,…”

Section: Exper Zu Schemamentioning

confidence: 99%

“…8.12 N-(l,2-Diryanethyl)iminomethylJ-3-hepten-l,7-dinitril 5,9,CH,); 3,50 (3, CHZ (2)); 4,91 (td, J, = 6,0, J d = 1,2, CH); 6,47 (t, J = 7,2, CH(4)); 8,14 (dd, J = 1,4, 0,4, CH-C (3)). I3C-NMR (CD, CN,75,47 MHz): 14,92,16,98,24,75,25,83 (41); 54,75 (d);117,15,117,32,118,4,120,46(4s,4CN); 132,61 (s,C(3)); 147,17, 167,25(2d) (E/Z)-35; 23% bzgl. verdampftem Material) 30 als braunes 01, das laut 'H-NMR weniger als 5 % Verunreinigungen (Fremdsignale bei hohem Feld) aufwies, gefolgt von 15 mg Nebenfraktion (Ma Farbung rnit Ehrlich-Reagenz; nach 300-MHz-IH-NMR komplexes Gemisch).…”

Section: Exper Zu Schemaunclassified

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Chemie der α‐Aminonitrile 1. Mitteilung Einleitung und Wege zu Uroporphyrinogen‐octanitrilen

Ksander¹,

Bold

Lattmann

et al. 1987

Helvetica Chimica Acta

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Chemistry of α‐Aminonitriles I: Introduction and Pathways to Uroporphyrinogen‐octanitriles. An introduction to experimental studies on the chemistry of α‐aminonitriles potentially relevant to the problems of prebiotic chemistry is presented. The framework of conditions wherein the investigation is chosen to be carried out implies both molecular oxygen and ‐ whenever feasible ‐ water to be excluded from reaction conditions. This study focusses on 2‐amino‐2‐propenenitrile (3) (Scheme 6) as central starting material of reaction sequences which aim at the nitrile forms of proteinogenic amino acids as well as at the aza forms of building blocks of biological cofactor molecules as their targets (Scheme 5). Schemes 13,16,23 as well as 25 and 26 summarize reaction sequences by which 3 is transformed within the defined framework of conditions into the thermodynamic (statistically controlled) mixture of the four isomeric uroperphyrinogen‐octanitriles 57–60. HPLC's of such mixtures document the dominance of the least symmetrical isomer whose constitutional pattern of peripheral substituents happens to be the one percent in all biological porphinoids. Preparative procedures for the synthesis of 3(Scheme 9), the β,β‐disubstituted pyrrol‐nitriles 30,53 and 54 (Scheme 19) as well as the porphyrinogenoctakis(propionitrile) and‐octakis(acetonitrile) 65 and 66, respectively (Scheme 24) are given.

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“…To find an answer to the question concerning the significance of H-bonds as presented in General remarks. S. [23] [24]. The procedure followed during a 'usual' or 'normal' extraction is described in [23].…”

Section: Bmentioning

confidence: 99%

Cob(I)alamin as Catalyst. 8th Communication. Cob(I)alamin and Heptamethyl Cob(I)yrinate During the Reduction of α,β‐Unsaturated Carbonyl Derivatives

Fischli

Daly

1980

Helvetica Chimica Acta

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SummaryHydrogen bonds as presented in Figure 2 cannot account for the enantioselective attack of cob (1)alamin (4 (I)) or heptamethyl cob (1)yrinate (5 (I)) on one of the two enantiotopic faces of the substrates. The attack of the strongly nucleophilic 3d,z orbital is preferentially directed to the re-side of the starting materials with (2)-configuration and leads, after the highly stereoselective reductive cleavage of the Co,C bond, to saturated products with (9-configuration in varying enantiomeric excesses (see Schemes 1,3 and Table I).1. Introduction. -The enantioselective reduction of the a,P-unsaturated ester 1 using cob (1)alamin (4 (I); see Schemes 1 and 2 ) has been published in two earlier communications in these series (21 [3]. The product was shown to be the corresponding saturated ester 3 with (S)-configuration at the chiral center showing enantiomeric excesses of 16.2-23.8% depending on the reaction conditions applied. The formation of alkylcobalamins by a nucleophilic attack of cob (1) It is therefore reasonable to expect intermediate alkylcobalamins during this overall reduction of a double bond. It has been shown in an earlier paper [l] that the reductive cleavage of a Co,C bond follows 97% retention of configuration at the C-atom using zinc as electron source in aqueous acetic acid. The mechanistic pathway followed in this enantioselective reduction can therefore be outlined as shown in Scheme 1. Cob (1)alamin (4 (I)) attacks the electrophilic C-atom in position 3 of 1 with the lobe of the 3d,~orbital on the P-side of the catalyst2). This attack

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Carotinoidsynthesen über Sulfone; Synthese von β‐Carotin

Cited by 23 publications

References 11 publications

Intramolecular ring opening of a 2,3‐epoxy alcohol by a xanthate anionic center; stereospecific preparation of 2‐mercapto‐1,3‐diol units

Intramolecular ring opening of a 2,3‐epoxy alcohol by a xanthate anionic center; stereospecific preparation of 2‐mercapto‐1,3‐diol units

Chemie der α‐Aminonitrile 1. Mitteilung Einleitung und Wege zu Uroporphyrinogen‐octanitrilen

Cob(I)alamin as Catalyst. 8th Communication. Cob(I)alamin and Heptamethyl Cob(I)yrinate During the Reduction of α,β‐Unsaturated Carbonyl Derivatives

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