Use of aza-Cope rearrangement-Mannich cyclization reactions to achieve a general entry to Melodinus and Aspidosperma alkaloids. Stereocontrolled total syntheses of (.+-.)-deoxoapodine, (.+-.)-meloscine, and (.+-.)-epimeloscine and a formal synthesis of (.+-.)-1-acetylaspidoalbidine

Overman, Larry E.; Robertson, Graeme M.; Robichaud, Albert J.

doi:10.1021/ja00007a038

Cited by 115 publications

(59 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The next step was to reduce the aminal to the indoline intermediate 9. The stereochemistry was controlled by taking advantage of the difference between the thermodynamic stability of the cis-and trans-A C H T U N G T R E N N U N G [5,6] fused ring systems. Following the treatment with trifluoroacetic acid in acetonitrile and sodium cyanoborohydride, the TBS protecting group was removed using dilute aqueous hydrochloric acid in methanol to furnish in 87% overall yield the desired tricyclic intermediate 9, which was oxidized in 91% yield to the corresponding enal with the proper set-up of all the functionalities for the key tandem Michael addition.…”

Section: Intramolecular [4+2]/a C H T U N G T R E N N U N G [3+2]mentioning

confidence: 99%

“…For example, there are six total syntheses so far that have been documented towards the construction of 1-acetylA C H T U N G T R E N N U N G aspidoalbidine and/or 1-methylaspidospermidine. To briefly summarize the previous synthetic efforts, Ban [5] used a relatively complex intermediate that was developed in his previous investigations to furnish 1-acetylaspidoalbidine; Overman [6] applied the aza-Cope rearrangement-Mannich cyclization reactions to achieve a general entry to Melodinus and Aspidosperma alkaloids; Boger [7] relied on a powerful …”

mentioning

confidence: 99%

See 1 more Smart Citation

Total Synthesis of (±)‐1‐Acetylaspidoalbidine and (±)‐1‐Methylaspidospermidine

Jin¹,

Qiu²

2014

Adv Synth Catal

View full text Add to dashboard Cite

show abstract

Section: Intramolecular [4+2]/a C H T U N G T R E N N U N G [3+2]mentioning

confidence: 99%

mentioning

confidence: 99%

Total Synthesis of (±)‐1‐Acetylaspidoalbidine and (±)‐1‐Methylaspidospermidine

Jin¹,

Qiu²

2014

Adv Synth Catal

View full text Add to dashboard Cite

show abstract

“…26 The usefulness of this strategy was specially highlighted by Overman's group. 27 Substrates 38 showing a gem-disubstituted olefinic double bond are much more reactive than their analogs in which the olefinic chain is unsubstituted. When substituted, the N-homoallyl chain is more prone to react since the transient positive charge of the transition state (vide infra) is in part located on a tertiary carbon atom and is therefore stabilized.…”

Section: Scheme 10mentioning

confidence: 99%

Asymmetric Synthesis of α-Amino Acids from a Chiral Masked Form of Glyoxal

Agami

Couty

Puchot-Kadouri

1998

Synlett

View full text Add to dashboard Cite

Synthetic works devoted to the synthesis of α-amino acids are simply plethoric. The primary impetus which accounts for such a strong interest clearly is the potential of the target molecules to lead to practical applications associated with their biological interest. On the other hand, and this is a familiar rule in science, research towards this practical objective gave birth to the invention of new important synthetic methodologies and it can be stated that many achievements in this field are unquestionable landmarks in asymmetric synthesis. 1 Among the various methods that give access to optically active α-amino acids, one of the more documented consists in the use of electrophilic glycine equivalents. Fiaud and Kagan, as early as 1970, pioneered this field by reacting Grignard reagents with chiral imines. 2 Since then, this area expanded very rapidly and the syntheses using bis-lactim ethers and oxazinones developed respectively by Schöllkopf's and Williams' groups 3,4 are now considered as classical.In this respect, we have presented a chiral masked form of glyoxal derived from β-amino alcohols. This is another electrophilic glycine equivalent which appeared as an extremely convenient tool for the design of enantiopure acyclic as well as cyclic α-amino acids. This methodology is based on desymmetrization of glyoxal which was transformed into a chiral template. The crucial step of this procedure involves an iminium ion derived from one aldehyde function of glyoxal. This iminium ion was used as a substrate by applying either one of the following processes: (i) intermolecular addition of organozinc reagents or silyl derivatives, (ii) intramolecular ene-iminium reactions entailing an ene moiety linked to the template. Acyclic N-methyl amino acids resulted from the first process whereas the second one afforded proline or pipecolic acid-derived amino acids. In both cases, the reactions between the iminium moiety and its nucleophilic partner occurred with complete stereocontrol. The more significant aspects of this research are presented here. Condensation of glyoxal with chiral β-amino alcoholsWe have been interested for a long time in the stereoselective formation of oxazolidines 1 which result from the condensation of β-amino alcohols with aldehydes. 5 In the case of glyoxal however, it was reported by Le Rouzic et al. 6 , on the basis of X-ray analysis, that similar condensations afforded a 6-membered ring compound 2 (Scheme 1). Treated with thiophenol, heterocycle 2 was cleaved and yielded morpholine derivative 3. Scheme 1This fact strongly attracted our attention because compound 3 can be envisioned as a masked form of glyoxal in which the two original aldehydic functions are now discriminated. We thought that the use of chiral β-amino alcohols would afford a further interesting differentiation, i.e. between the enantiofaces of the glyoxal carbonyl groups.Abstract: Enantiopure acyclic and cyclic α-amino acids were synthesized from glyoxal. This dialdehyde was desymmetrized by condensing it with various (R)-ph...

show abstract

“…Overman and coworkers have published a full account of their synthesis of (±)-meloscine (956a) and (±)-16-epimeloscine (956b) already in 1991 9,10 . The synthesis features azonia-Cope rearrangement/Mannich cyclization as the crucial ring-forming sequence, review 11,12 .…”

Section: Overman's Synthesis Of (±)-Meloscinementioning

confidence: 99%

Recent developments in syntheses of the post-secodine indole alkaloids. Part III: Rearranged alkaloid types

Hájíček¹

2011

Collect. Czech. Chem. Commun.

View full text Add to dashboard Cite

The third part of a planned review on developments in the field of total and formal total synthesis of the post-secodine indole alkaloids focuses on types of rearranged alkaloids, i.e. on the skeletons with altered connectivities next to the indol(e)ine moiety, especially with a new bond to N-1. It reviews the synthesis of melodane, goniomitine, chippiine/dippinine, lirofoline and tronocarpine alkaloids, as well as alkaloids of secoschizozygane/vallesamidine, schizozygane and isoschizozygane type. It covers the literature from approximately 1991 up to May 2011. A review with 115 references.

show abstract

Use of aza-Cope rearrangement-Mannich cyclization reactions to achieve a general entry to Melodinus and Aspidosperma alkaloids. Stereocontrolled total syntheses of (.+-.)-deoxoapodine, (.+-.)-meloscine, and (.+-.)-epimeloscine and a formal synthesis of (.+-.)-1-acetylaspidoalbidine

Cited by 115 publications

References 0 publications

Total Synthesis of (±)‐1‐Acetylaspidoalbidine and (±)‐1‐Methylaspidospermidine

Total Synthesis of (±)‐1‐Acetylaspidoalbidine and (±)‐1‐Methylaspidospermidine

Asymmetric Synthesis of α-Amino Acids from a Chiral Masked Form of Glyoxal

Recent developments in syntheses of the post-secodine indole alkaloids. Part III: Rearranged alkaloid types

Contact Info

Product

Resources

About