<b>General Base-General Acid-Catalysis of Ester Solvolysis</b>

Kupchan, S. Morris; Eriksen, Stuart P.; Friedman, Mendel

doi:10.1021/ja00880a044

Cited by 13 publications

(8 citation statements)

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“…In the case of alkaloidal esters, the authors postulate the involvement of the unshared electron pair of the ring nitrogen atoms in the catalysis. Although such facilitated solvolysis, the so-called Henbest-Kupchan effect ( Kupchan et al, 1962), of glycosidic bonds of the glycoalkaloids could not occur under the conditions of the present study, where the nitrogens are protonated, it could take place at higher pH values. Therefore, under basic conditions, the extent of intramolecular catalysis of hydrolysis of carbohydrate groups of the glycoalkaloids should be directly related to the nucleophilicities of the steroidal ring nitrogen atoms, as measured by basicities or pK values.…”

Section: Hydrolysis Ofmentioning

confidence: 55%

Kinetics of acid-catalyzed hydrolysis of carbohydrate groups of potato glycoalkaloids .alpha.-chaconine and .alpha.-solanine

Friedman¹,

McDonald²,

Haddon³

1993

J. Agric. Food Chem.

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Section: Hydrolysis Ofmentioning

confidence: 55%

Kinetics of acid-catalyzed hydrolysis of carbohydrate groups of potato glycoalkaloids .alpha.-chaconine and .alpha.-solanine

Friedman¹,

McDonald²,

Haddon³

1993

J. Agric. Food Chem.

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“…9. N ( a ) , 1 l-Di-~?zethoxycarbonyl-3-ono-I0,1 I-dehydro-aspidofraktinin ( 9 (4,13), 316 (4,16) ; Amin 224 (4,02), 272 (3,67); lsch ca. 290 (3,9).…”

Section: I3irliogrhphieunclassified

“…Dic Verbindung 11 criiiclt man auch dirckt clurch lictluktion \'on 9, wic in Versuch 1 3 bcschrieben. 13. h d n k t i o n uon 9 zzi 11: Einc Probe von 9, gclost im Gemisch 5~ wasseriger H2S04/CH,0H ljl, versetzte man niit Zinkstaub und erhitzte die Mischung 1 Std.…”

Section: I3irliogrhphieunclassified

Ein neuer Abbau des Indolalkaloids Kopsin; chemische Korrelierung der Alkaloide vom Kopsin‐ und Pleiocarpin‐Typ mit Minovincin

Guggisberg

Gorman

Bycroft

et al. 1969

Helvetica Chimica Acta

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A new chemical degradation of (–)‐kopsine is described which completely confirms the structure of this alkaloid. Correlation of (–)‐aspidofractinine, (–)‐pleiocarpine and (–)‐kopsine with (–)‐minovincine establishes the absolute stereochemistry of these bases. It appears that, in contrast to the aspidospermine group, all alkaloids containing the aspidofractinine skeleton possess the same absolute stereochemistry.

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“…(22), 660 (14), 659 (14), 644 (lo), 643 (12), 632 (12), 630 (14), 602 (13), 450 (Z), 437 (l), 420 (Z), 408 (l), 39.3 (9), 365 (4), 351 (M++, S ) , 330 (660++, 9), 265 (7), 252 (60), 237 (24). 223 (16), 208 (35), 197 ( 2 2 ) , 156 (21).…”

Section: )unclassified

“…Massenspektrum: 688 (Mf f14, 26), 674 (Aft, loo), 644 (9), 604 (4), 588 (4), 574 (5), 489 (I), 422 (4), 409 (7), 337 (AT++, 13), 278 (4), 26.5 (6), 2.52 (42), 237 (13), 208 (23), 202 (9), 197 (18), 185 (lo), 180 (lo), 170 (la), 156 (13), 144 (6), 123 (15), 122 (16). 732 ( M + , 30), 687 (13), 673 (loo), 573 (7), 521 (4). 507 (30).…”

Section: )unclassified

Umbellamin, ein neues «dimeres» Indolalkaloid 130. Mitteilung über Alkaloide [1]

Morita

Hesse

Schmid

1969

Helvetica Chimica Acta

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Umbellamine (f; C41H48N4O4), a «dimeric» indole‐indoline alkaloid, was isolated from the root bark of Hunteria umbellata (K. SCHUM.) HALL. F.; it is probably identical with the alkaloid hunterine (structure unknown) of NeUSS & CONE [14]. Thermolysis yielded (+)‐eburnamenine (II), whereas a detailed mass spectrometric study of I, of its O‐methyl and O‐acetyl derivatives, and also of the derived diol V revealed the presence of a phenolic hydroxy‐pseudoakuammigine group as second part, the benzene nucleus of the latter being linked to the C‐14 atom of the eburnamenine component (present in the dihydrom form). The n.m.r. study of umbellamine and of its derivatives showed that the phenolic hydroxy group is either at C‐10′ or C‐11′ and that the dihydroeburnamenyl residue is connected to C‐11′ or C‐10′ of the pseudoakuammigine residue. A choice between these alternatives was possible by investigation of the hydroxylated base IX arising from the latter component, and obtained in small quantities by treatment of umbellamine with zinc or tin in acid. Its constitution, deduced by uv., n.m.r. and mass spectrometry, suggested that the hydroxy group is fixed at C‐11′. If this is correct, the dihydrocburnatnenyl residue is linked to C‐10′ of the pseudoakuarnmigine residue. Thus we propose formula I for umbellamine.

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General Base-General Acid-Catalysis of Ester Solvolysis

Cited by 13 publications

References 0 publications

Kinetics of acid-catalyzed hydrolysis of carbohydrate groups of potato glycoalkaloids .alpha.-chaconine and .alpha.-solanine

Kinetics of acid-catalyzed hydrolysis of carbohydrate groups of potato glycoalkaloids .alpha.-chaconine and .alpha.-solanine

Ein neuer Abbau des Indolalkaloids Kopsin; chemische Korrelierung der Alkaloide vom Kopsin‐ und Pleiocarpin‐Typ mit Minovincin

Umbellamin, ein neues «dimeres» Indolalkaloid 130. Mitteilung über Alkaloide [1]

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