Approach to 6a-Epipretazettine and 6a-Epiprecriwelline via an Intramolecular 2-Azaallyl Anion Cycloaddition Reaction

Pearson, William H.; Postich, Michael J.

doi:10.1021/jo00098a026

Cited by 66 publications

(33 citation statements)

References 2 publications

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“…Examples include the total synthesis of crinine [12,13], amabiline [13,14] mine [13,14], and an approach to 6a-epipretazettine [15]. Three additional examples of these efforts are briefly described below.…”

Section: -Azaallyllithium Cycloadditionsmentioning

confidence: 99%

Alkaloid synthesis via [3+2] cycloadditions

Pearson

2002

Pure and Applied Chemistry

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Tin-lithium exchange on (2-azaallyl)stannanes affords nonstabilized 2-azaallyllithiums (2-azaallyl anions) that undergo [π4s+π2s] cycloadditions with alkenes to afford pyrrolidines. The scope of this method has been expanded to include 2-azapentadienyllithiums and heteroatom-substituted 2-azaallyllithiums. Alternatively, the (2-azaallyl)stannanes may also be used to generate nonstabilized azomethine ylides via N-alkylation/destannylation or N-protonation/destannylation, and these ylides were also found to be useful for the synthesis of pyrrolidines by [π4s+π2s] cycloadditions with alkenes. Applications of both methods to the total synthesis of alkaloids such as (+)-coccinine, lepadiformine stereoisomers, lapidilectine B, and indolizidine 239CD have been accomplished.

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Section: -Azaallyllithium Cycloadditionsmentioning

confidence: 99%

Alkaloid synthesis via [3+2] cycloadditions

Pearson

2002

Pure and Applied Chemistry

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“…1 Accordingly, novel strategies for the stereoselective synthesis of hetero-polycyclic ring systems continue to receive considerable attention in the field of synthetic organic chemistry. 2,3,4,5,6,7,8 The efficiency with which heterocycles can be constructed is important not only because it affects the production costs for the desired material, but also the environmental impact associated with waste disposal, conservation of source materials like petroleum stocks, and energy consumption. The rate of increase in molecular intricacy as one progresses from simple starting materials to the final product can serve as a measure of efficiency.…”

Section: Introductionmentioning

confidence: 99%

The domino way to heterocycles

Padwa¹,

Bur²

2007

Tetrahedron

385

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Sequential transformations enable the facile synthesis of complex target molecules from simple building blocks in a single preparative step. Their value is amplified if they also create multiple stereogenic centers. In the ongoing search for new domino processes, emphasis is usually placed on sequential reactions which occur cleanly and without forming by-products. As a prerequisite for an ideally proceeding one-pot sequential transformation, the reactivity pattern of all participating components has to be such that each building block gets involved in a reaction only when it is supposed to do so. The development of sequences that combine transformations of fundamentally different mechanisms broadens the scope of such procedures in synthetic chemistry. This mini review contains a representative sampling from the last 15 years on the kinds of reactions that have been sequenced into cascades to produce heterocyclic molecules.

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“…After heating for 2 h, the reaction mixture was concentrated under reduced pressure and subjected to flash silica gel chromatography to give 0.13 g (69%) of cycloadduct 36 as a pale yellow oil; IR (neat) 2935, 2857, 1758, 1733, 1607, 1480, and 1252 4.30-4.40 (m, 2H), 7.14 (t, 1H, J = 7.3 Hz), and 7.34-7.41 (m, 3H); 13 C-NMR (100 MHz, CDCl 3 ) δ −3. 6,14.2,18.5,21.8,25.9,28.0,33.6,36.0,43.8,62.3,75.3,91.2,102.4,114.5,124.8,131.0,135.3,136.4,164.0,and 165.1;HRMS Calcd. for [C 24 H 33 NO 5 Si + H + ]: 444.2201.…”

Section: Rh(ii)-catalyzed Dipolarmentioning

confidence: 99%

The rhodium(II) carbenoid cyclization–cycloaddition cascade of α-diazo dihydroindolinones for the synthesis of novel azapolycyclic ring systems

et al. 2008

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Tandem carbonyl ylide formation-1,3-dipolar cycloaddition of α-diazo N-acetyl-tetrahydro-β-carbolin-1-one derivatives occur efficiently in the presence of a dirhodium catalyst to afford bimolecular cycloadducts in high yield. The Rh(II)-catalyzed reaction also takes place intramolecularly to give products derived from trapping of the carbonyl ylide dipole with a tethered alkene. The power of the intramolecular cascade sequence is that it rapidly assembles a pentacyclic ring system containing three new stereocenters and two adjacent quaternary centers stereospecifically in a single step and in high yield.

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Approach to 6a-Epipretazettine and 6a-Epiprecriwelline via an Intramolecular 2-Azaallyl Anion Cycloaddition Reaction

Cited by 66 publications

References 2 publications

Alkaloid synthesis via [3+2] cycloadditions

Alkaloid synthesis via [3+2] cycloadditions

The domino way to heterocycles

The rhodium(II) carbenoid cyclization–cycloaddition cascade of α-diazo dihydroindolinones for the synthesis of novel azapolycyclic ring systems

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