Additionsreaktionen an der alicyclischen Doppelbindung von Eburnamenin und Apovincamin

Pfäffli, Paul; Hauth, H.

doi:10.1002/hlca.19780610516

Cited by 37 publications

(13 citation statements)

References 10 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Treatment of 20a with MeOH, (MeO) 3 CH, and p -toluenesulfonic acid gave the acetal 20b and free radical bromination of 20b provided (+)- 1a . This substance was found to be identical ( 1 H and 13 C NMR, TLC, IR) to (+)-apovincamine that had been prepared from natural vincamine by literature procedures . The conversion of apovincamine to vincamine ( 2 ) has been reported by Oppolzer and co-workers …”

Section: Resultssupporting

confidence: 62%

Asymmetric Total Synthesis of (+)-Apovincamine and a Formal Synthesis of (+)-Vincamine. Demonstration of a Practical “Asymmetric Linkage” between Aromatic Carboxylic Acids and Chiral Acyclic Substrates

1997

View full text Add to dashboard Cite

Asymmetric syntheses of (+)-apovincamine (1a) and (+)-vincamine (2) are described. Construction of the pentacyclic diene lactam 14, a pivotal intermediate for synthesis of the cis-fused vincane-type alkaloids, began by Birch reduction−alkylation of the chiral benzamide 3 to give the 6-ethyl-1-methoxy-4-methyl-1,4-cyclohexadiene 4. Conversion of 4 to 2,5-cyclohexadienone 5 (92% overall yield from 3) and HPLC analysis of 5 demonstrated the diastereomeric purity resulting from the Birch reduction−alkylation to be >100:1. Dienone 5 was converted to butyrolactone 9 (47% overall yield from 3), and 9 was coupled with tryptamine (10) to give the amide 11a. Amido keto aldehyde 13 was obtained from 11a, and acid-catalyzed tricyclization and subsequent base-induced elimination of MeOH provided the desired cis-fused pentacyclic diene lactam 14. Examination of the two-step process 13 → 14 revealed a novel base-induced epimerization at C(21) which served to interconvert 14 and 17, possibly by the involvement of a homoenolate. Diene lactam 14 was converted to (+)-apovincaminal 20a, an intermediate in the synthesis of (+)-apovincamine (1a) reported by Winterfeldt and co-workers. A new procedure for conversion of 20a to 1a involves conversion of 20a to the acetal 20b and treatment of 20b with NBS/AIBN in CCl4. The conversion of 1a to vincamine (2) has been reported by Oppolzer and co-workers.

show abstract

Section: Resultssupporting

confidence: 62%

Asymmetric Total Synthesis of (+)-Apovincamine and a Formal Synthesis of (+)-Vincamine. Demonstration of a Practical “Asymmetric Linkage” between Aromatic Carboxylic Acids and Chiral Acyclic Substrates

1997

View full text Add to dashboard Cite

show abstract

“…The ability of chiral secondary amines to promote iminium and enamine activation of α,β-unsaturated aldehydes 2 in one catalytic cycle will be the centerpiece of the desymmetrization strategy toward hydroindole structures. This is a common motif in natural substances and biorelevant compounds such as the alkaloids thelepogine, eburenine, and dihydro-β-erythroidine (DHβE) . Central to the implementation of the desymmetrization is the addition of para -quinamines 1 to α,β-unsaturated aldehydes 2 .…”

mentioning

confidence: 99%

Enantioselective Desymmetrization ofpara-Quinamines through an Aminocatalyzed Aza-Michael/Cyclization Cascade Reaction

et al. 2015

View full text Add to dashboard Cite

An unprecedented organocatalytic asymmetric desymmetrization of para-quinamines leading to functionalized hydroindoles, a common motif in many alkaloids, has been reported. The ability of diarylprolinol silyl ethers to promote iminium and enamine activation of α,β-unsaturated aldehydes in one catalytic cycle is the centerpiece of the strategy involving a challenging aza-Michael/intramolecular cyclization cascade reaction. A range of prochiral para-quinamines and α,β-unsaturated aldehydes were investigated to afford 16 examples of hydroindoles possessing four contiguous stereocenters including one quaternary carbon. The hydroindole structures include multiple orthogonal functionalities, which underwent various transformations.

show abstract

“…Nine new and 13 known alkaloids were isolated and characterized using physical data analysis. The known alkaloids include pleiomutinine, huncaniterine A, geissoschizol, dihydrocorynantheol, isositsirikine, epiyohimbol, yohimbol, pleiocarpamine, ( S )-dihydroakuammicine, vincadifformine, O -methyleburnamine, O -methylisoeburnamine, and 10-hydroxy- N b -methylgeissoschizol . The alkaloids have been screened for their cytotoxicity against human cancer cell lines and insecticidal activity against the aphid, Rhodobium porosum .…”

mentioning

confidence: 99%

Indole Alkaloids from Hunteria zeylanica

et al. 2017

View full text Add to dashboard Cite

Six new bisindole alkaloids, hunterizeylines A-F (1-6), three new monomers, hunterizeylines G-I (7-9), and 13 known alkaloids were isolated from an aqueous MeOH extract of the twigs and leaves of Hunteria zeylanica. Hunterizeyline H, geissoschizol, and dihydrocorynantheol displayed weak insecticidal activity against the aphid Rhodobium porosum, with IC values of 168.2, 360.5, and 290.6 μM, respectively.

show abstract

Additionsreaktionen an der alicyclischen Doppelbindung von Eburnamenin und Apovincamin

Cited by 37 publications

References 10 publications

Asymmetric Total Synthesis of (+)-Apovincamine and a Formal Synthesis of (+)-Vincamine. Demonstration of a Practical “Asymmetric Linkage” between Aromatic Carboxylic Acids and Chiral Acyclic Substrates

Asymmetric Total Synthesis of (+)-Apovincamine and a Formal Synthesis of (+)-Vincamine. Demonstration of a Practical “Asymmetric Linkage” between Aromatic Carboxylic Acids and Chiral Acyclic Substrates

Enantioselective Desymmetrization ofpara-Quinamines through an Aminocatalyzed Aza-Michael/Cyclization Cascade Reaction

Indole Alkaloids from Hunteria zeylanica

Contact Info

Product

Resources

About