Mechanism and Stereochemical Course of Acyl Migrations in Derivatives of Ephedrine and ψ-Ephedrine

Welsh, Llewellyn H

doi:10.1021/ja01178a071

Cited by 75 publications

(17 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Emde (I) first suggested that this conformational difference existed and the 11-orl; of Welsh (4), Kagai a1lc1 ICanoa ( 5 ) , and Fodor and ICoczka (6) further suggested that in the #-ephedrines the hydroxyl and amino functional groups were spatially in a prefei-1-etl gauche conformation, while in the ephedrines the trans disposition about the Co-Cx bond \?-as preferred. Close (7) explained the production of an oxazolidone from +-ephedi-ine on fusion with urea compared with a 1 imidazolidone on similar treatment of ephedrine on the basis of a preferred gauche dispositioil of the hydroxyl and amino groups in +-ephedrine compared with trans in ephedrine.…”

Section: Configuration Of the Ephedrines C61-15ch(om)ch(xhci-i~)chr T Tmentioning

confidence: 99%

Hydrogen Bonding in Diastereoisomeric Α-Β Aminoalcohols: A Reinvestigation of the Ephedrines by N.M.R

Hyne¹

1960

Can. J. Chem.

View full text Add to dashboard Cite

show abstract

Section: Configuration Of the Ephedrines C61-15ch(om)ch(xhci-i~)chr T Tmentioning

confidence: 99%

Hydrogen Bonding in Diastereoisomeric Α-Β Aminoalcohols: A Reinvestigation of the Ephedrines by N.M.R

Hyne¹

1960

Can. J. Chem.

View full text Add to dashboard Cite

show abstract

“…We attribute this spectrum to the quaternary compound 7 (Scheme l), the absorption at -1.0 T being that of the (exchanging) protons 'Exceptions have been noted, however, in which stereochemistry is retained (7,12,13).…”

Section: Cophmentioning

confidence: 92%

Substituent Interactions in Di- and Tri-acyl Derivatives of cis- and trans- 2-Hydrazinocyclopentanol

Campbell¹,

Mackay²

1973

Can. J. Chem.

View full text Add to dashboard Cite

The action of thionyl chloride followed by an alkaline work-up quantitatively isomerizes trans-1,2-dibenzoyl-1-(2-h~droxylcyclopentyl)hydrazine (5) to cis-2-benzoyl-I-(2-benzoyloxycyclopentyl)hydrazine (3). One equivalent of tosyl chloride in pyridine converts 5 to an intermediate which can be hydrolyzed to a mixture of 3 and 5 or can be transformed to the N-tosyl derivative 13 by tosylation and then hydrolysis. Oxazolidine structures are s~~ggested as intermediates for these reactions.The alcohol 2 can also be isomerized to 3, using 0.8 N aqueous ethanolic hydrochloric acid, to which 5 is inert. The ester 3 is again the major product in the hydrolysis by this acid mixture of the cis-tribenzoyl derivative 17, the cis-N,-p-anisoyl derivative 21a and the cis-N,-acetyl derivative 216, the amide group being cleaved much more rapidly than the ester, especially in the case of 216. A mechanism involving ester participation by way of an oxazolidinium cation is proposed for these amide hydrolyses, and this is supported by tracer studies.The trntu-esters 24n and b hydrolyze mainly at the ester group with retention of configuration. Polynlorphism is a common phenomenon among thc title compounds.L'action du chlor~lre de thionyle suivie d'un traitement alcalin isoniCrise quantitativement le traiudibenzoyl-1,2 (hydroxyl-2 cyclopenty1)-l hydrazine (5) en cis benzoyl-2 (benzoyloxy-2 cyclopenty1)-l hydrazine (3). Un equivalent de chlorure de tosyle dans la pyridine transforme 5 en un intermediaire qui peut Ctre hydrolyse en un melange d e 3 et 5 ou convertit en derive N-tosyle 1 3 par tosylation puis hydrolyse. Les structures oxazolidines ont ete suggCrees comme intermediaires reactionnels. L'isomCrisation de I'alcool2 en 3 est Bgalement possible en presence d'une solution aqueuse Cthanolique d'acide chlorhydrique 0.8 N pour laquelle 5 est inerte. L'ester 3 reste encore le produit majoritaire dans I'hydrolyse par ce melange acide, du derive cir-tribenzoyle 17, du derive cis N,-p-anisoyle 21a et du dCriv6 cis-N,-acetyle 21b, le groupe amide etant dive beaucoup plus rapidenlent que I'ester specialement dans le cas de 21b. Un mecanisme avec participation de I'ester par un cation oxazolidinium a CtC propose pour les hydrolyses de ces amides; ce mecanisme a ete confirm6 par les Ctudes par traceur.Les esters tratrs 24a et 6 s'hydrolysent principalement sur le groupe ester avec retention de configuration. Le polymorphisme est un phenomene conimun parlni les composes de cette etude.[Traduit par le journal]Can. J . Chcn., 51. 1587 (1973) In earlier work (1) we used as partial proof of the structure of 1, the dihydro derivative of the thermal rearrangement product of cyclopentadiene and azodibenzoyl, its ready hydrolysis by acid to cis-1,2-dibenzoyl-1-(2-hydroxycyclopenty1)hydrazine (2). The alcohol 2 was not itself isolated, but'rather its isomer, the ester 3, and the further hydrolysis product 4. The intermediacy of 2 ~ was, however, de~i~onstrated by t.l.c., and it was confirmed that under the hydrolysis conditions (0.8 N hydrochlor...

show abstract

“…Danach sollte sich ein aus einem Oxazolidinium-Ion gebildetes tetraedrisches Zwischenprodukt vom Typ D kinetisch kontrolliert zu einem 'Aminoester' E oder F und nicht zu einem 'Hydroxyamid' C offnen. Derartige Acyl-Verschiebungen sind wohlbekannt: neuere Beispiele [19]; Inversion unter Angriffeines Carbonyl-0-Atoms in einem Aminoalkohol-Derivat [20]; Wanderung von Ac-Gruppen unter Inversion in Kohlenhydraten [21]; klassische Arbeiten uber die Inversions-und Retentionswanderung der Benzoyl-Gruppe von N-Benzoylephedrinen [22] und uber die Epimerisierung am C(3) von Threonin [23], vgl. auch [24] [25]; Benzoyl-Wanderung in den Addukten von N-Benzoylimidazolidinonund N-Benzoyloxazolidinon-enolaten an Aldehyde und Ketone [26] [27]; N-0-Acyl-Wanderung in einem Peptid rnit OH-Gruppe in der Seitenkette (Cyclosporin) [28].…”

Section: Die Addition a X Bildung Yon 4a-19aunclassified

“…d) Die Rontgenstrukturanalyse des nach der Umsetzung mit Acetophenon isolierten Produktes 19a (Schema 2 ) beweist [I 51 dessen u-Konfiguration*"), im Kristall liegt eine intermolekulare H-Briicke zwischen der tertiiiren OH-Gruppe und dem Carbonyl-0-Atom des benachbarten Molekuls vor. e) Es ist bekannt")"), dass Acyl-Verschiebungen in I-(three)-konfigurierten Aminoethanol-Derivaten schneller verlaufen [22] als in den u-Isomeren, s. die vie1 grossere Stabilitat der Produkte 4a -17a, welchen wir u-Konfiguration zuordnenz4).…”

Section: )unclassified

Diasteroselektive Hydroxyalkylierungen in 1‐Stellung von Tetrahydroisochinolinen und Synthese von Aporphin‐, Protoberberin‐ und Phthalid‐Alkaloider

Seebàch¹,

Isabelle²,

Max³

1987

Helvetica Chimica Acta

View full text Add to dashboard Cite

Unsubstituted and 6,7-dialkoxy-N-pivaloyl-tetrahydroisoqu~nolines 1-3 are converted to l-bromomagnesium derivatives by sequential treatment with 1-BuLi (-75"/THF) and MgBrz.0Et2. Addition of the metalated tetrahydroisoquinolines to aliphatic or aromatic aldehydes occurs with relative topicity ul (Scheme 2). The I-hydroxyalkylated 2-pivaloyl-tetrahydroisoquinolines a of u-configuration thus obtained (14 examples) can be converted to free aminoalcohols c of either Ior u-configuration (9 examples; Scheme 3). The depivdloylation with retention (+ u-c) is best achieved by heating in EtOH/KOH, the conversion to 1 -aminoalcohols I-c by treatment with CF,COOH/(CF,CO),O (+ I -pivalates I-b), followed by alkaline saponification or by LiAIH4 reduction of the esters. The configuration of the products is assigned by 'H-NMR spectroscopy, by X-ray crystal structure analysis, by chemical correlation, and by comparison of the chemical properties of the Iand the u-isomers. The diastereoselective hydroxybenzylation of the tetrahydroisoquinoline is used for short syntheses of ushinsunine/ oliveroline (Scheme 4 ) , p-hydrastine, and ophiocarpine/epiophiocarpine (Scheme 6: aporphine, phthalide, and protoberberine alkaloids, respectively).

show abstract

Mechanism and Stereochemical Course of Acyl Migrations in Derivatives of Ephedrine and ψ-Ephedrine

Cited by 75 publications

References 0 publications

Hydrogen Bonding in Diastereoisomeric Α-Β Aminoalcohols: A Reinvestigation of the Ephedrines by N.M.R

Hydrogen Bonding in Diastereoisomeric Α-Β Aminoalcohols: A Reinvestigation of the Ephedrines by N.M.R

Substituent Interactions in Di- and Tri-acyl Derivatives of cis- and trans- 2-Hydrazinocyclopentanol

Diasteroselektive Hydroxyalkylierungen in 1‐Stellung von Tetrahydroisochinolinen und Synthese von Aporphin‐, Protoberberin‐ und Phthalid‐Alkaloider

Contact Info

Product

Resources

About