A Total Synthesis of (±)-3-<i>O</i>-Demethylmacronine through Rearrangement of a Precursor Embodying the Haemanthidine Alkaloid Framework

Ma, Xiang; Gao, Nadia Yuqian; Banwell, Martin G.; Carr, P.D.; Willis, Anthony C.

doi:10.1021/acs.joc.7b00340

Cited by 16 publications

(18 citation statements)

References 25 publications

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“…A total synthesis of 3- O -demethylmacronine, an Amaryllidaceae alkaloid, utilizing a lactam-to-lactone rearrangement of a twisted amide was reported by Banwell and co-workers (Figure 20) [46]. This elegant method capitalized on the high basicity of the twisted amide nitrogen atom to form the acylium ion, which underwent trapping with a pendant hydroxyl group under mild conditions.…”

Section: Application In Natural Product Synthesismentioning

confidence: 99%

Chemistry of Bridged Lactams: Recent Developments

Szostak

2019

Molecules

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Bridged lactams represent the most effective and wide-ranging method of constraining the amide bond in a non-planar conformation. A previous comprehensive review on this topic was published in 2013 (Chem. Rev. 2013, 113, 5701–5765). In the present review, which is published as a part of the Special Issue on Amide Bond Activation, we present an overview of the recent developments in the field of bridged lactams that have taken place in the last five years and present a critical assessment of the current status of bridged lactams in synthetic and physical organic chemistry. This review covers the period from 2014 until the end of 2018 and is intended as an update to Chem. Rev. 2013, 113, 5701–5765. In addition to bridged lactams, the review covers recent advances in the chemistry of bridged sultams, bridged enamines and related non-planar structures.

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Section: Application In Natural Product Synthesismentioning

confidence: 99%

Chemistry of Bridged Lactams: Recent Developments

Szostak

2019

Molecules

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“…The construction of the 2,5-methanotetrahydro-2 H -2-benzazepine skeleton ( 2 ) has been achieved through only three main strategies: Pictet–Spengler reaction ,− or a ring closure of the pyrrolidine derivative, , an intramolecular [3 + 2]-cycloaddition, , and via intramolecular N -alkylation . Other special examples have also been reported like lactamization …”

Section: Introductionmentioning

confidence: 99%

Chemoselective Strategy for the Direct Formation of Tetrahydro-2,5-methanobenzo[c]azepines or Azetotetrahydroisoquinolines via Regio- and Stereoselective Reactions

Kovács

Huszka

Gáti³

et al. 2019

J. Org. Chem.

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The present study reports regio- and highly diastereoselective preparative methods for the synthesis of versatile alkaloid-type compounds from oxiranylmethyl tetrahydroisoquinolines. 2,5-Methanobenzo[c]azepines or azetidine-fused heterocycles were synthesized in tandem reactions depending on the absence or presence of a BF3 co-reagent. A high functional group tolerance has also been demonstrated. DFT calculations with an explicit solvent model confirmed the proposed reaction mechanisms and the role of kinetic controls on the stereochemical outcome of the reported new methods.

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“…A range of significant biological effects has been attributed to such compounds, including, for example, antiviral and antitumor properties . Given this and the often-limited availability of certain of these alkaloids from their natural sources, significant attention has been directed toward their synthesis. ,,− Some of these efforts have been focused on the synthesis of compound 1 , a.k.a. crinane (which is not itself a natural product). , Wildman reported the first synthesis of (±)-crinane in 1956, the final step of which involved forming the D-ring by subjecting a C3a-arylated perhydroindole (embodying the ACD-ring system) to a Pictet–Spengler cyclization reaction.…”

Section: Introductionmentioning

confidence: 99%

“…We have an ongoing interest in the synthesis of crinane-type alkaloids and related compounds and established various means for assembling them, including by using cyclopropane ring-expansion, intramolecular Alder-ene cyclization, and Claisen-type rearrangement reactions . In connection with another study, we became interested in establishing the viability of a radical cyclization route to Wildman’s C3a-arylated perhydroindole.…”

Section: Introductionmentioning

confidence: 99%

Total Synthesis of (±)-Crinane from 6,6-Dibromobicyclo[3.1.0]hexane Using a 5-exo-trig Radical Cyclization Reaction to Assemble the C3a-Arylated Perhydroindole Substructure

2018

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Crinane embodies the tetracyclic framework associated with some of the most common Amaryllidaceae alkaloids. It has now been prepared in 10 steps from 6,6-dibromobicyclo[3.1.0]hexane (2). The initial step involves the thermally induced electrocyclic ring opening of cyclopropane 3 and capture of the resulting π-allyl cation with benzylamine to give an allylic amine that is readily elaborated to the 3°-amine 10. This last compound was engaged in a 5- exo- trig free radical cyclization reaction to give the C3a-arylated perhydroindole 11. Compound 11 was then converted, over two steps, into (±)-crinane, the hydrochloride salt of which has been subjected to single-crystal X-ray analysis.

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A Total Synthesis of (±)-3-O-Demethylmacronine through Rearrangement of a Precursor Embodying the Haemanthidine Alkaloid Framework

Cited by 16 publications

References 25 publications

Chemistry of Bridged Lactams: Recent Developments

Chemistry of Bridged Lactams: Recent Developments

Chemoselective Strategy for the Direct Formation of Tetrahydro-2,5-methanobenzo[c]azepines or Azetotetrahydroisoquinolines via Regio- and Stereoselective Reactions

Total Synthesis of (±)-Crinane from 6,6-Dibromobicyclo[3.1.0]hexane Using a 5-exo-trig Radical Cyclization Reaction to Assemble the C3a-Arylated Perhydroindole Substructure

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