Synthetic approach to diterpene alkaloids: Construction of the bridged azabicyclic ring system of kobusine.

Shibanuma, Yoshihisa; Okamoto, Toshihiko

doi:10.1248/cpb.33.3187

Cited by 30 publications

(12 citation statements)

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“…Attractive strategies to access 6-TMS-2,3-dihydro-4-pyridone moieties such as 28 have been reported, most notably involving the addition of silyl-Grignard nucleophiles to N-acyl-4-methoxypyridinium derivatives. [55,56] Unfortunately, the impracticality of late stage Ndeprotection and subsequent neopentyl N-alkylation to form dihydropyridones such as 21 (i.e., Scheme 3) led us to consider an alternate, more flexible approach, incorporating an iminehetero-Diels-Alder reaction employing Danishefsky's diene (27,Scheme 4). [57] To investigate this plan, the preparation of a model α-TMS-dihydropyridone 28 would require access to a Csilyl aldimine dienophile such as 26.…”

Section: 3-dipolar Cycloaddition Via Non-stabilized Endocyclic Azommentioning

confidence: 99%

Asymmetric Synthetic Access to the Hetisine Alkaloids: Total Synthesis of (+)‐Nominine

Peese

Gin

2008

Chemistry A European J

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A dual cycloaddition strategy for the synthesis of the hetisine alkaloids has been developed, illustrated by a concise asymmetric total synthesis of (+)-nominine (7). The approach relies on an early-stage intramolecular 1,3-dipolar cycloaddition of a 4-oxido-isoquinolinium betaine dipole with an enenitrile dipolarophile. Subsequent late-stage pyrrolidine-induced dienamine isomerization/DielsAlder cascade allows for rapid construction of the carbon-nitrogen polycyclic skeleton within this class of C 20 -diterpenoid alkaloids.

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Section: 3-dipolar Cycloaddition Via Non-stabilized Endocyclic Azommentioning

confidence: 99%

Asymmetric Synthetic Access to the Hetisine Alkaloids: Total Synthesis of (+)‐Nominine

Peese

Gin

2008

Chemistry A European J

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“…Distinctive structural characteristics of the hetisan framework are the atidane skeleton and the presence of the NC6 and C14C20 bonds, which contribute to the difficulty of synthesizing the hetisine‐type alkaloids. Shibanuma and Okamoto prepared a pentacyclic compound that contains the NC6 bond 8. Two other reports that describe synthetic studies of hetisine‐type alkaloids have also appeared 9…”

Section: Methodsmentioning

confidence: 99%

Total Synthesis of (±)‐Nominine, a Heptacyclic Hetisine‐Type Aconite Alkaloid

Muratake

Natsume

2004

Angew Chem Int Ed

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The barrier has finally been lifted to the synthesis of hetisine‐type alkaloids with the total synthesis of (±)‐nominine (1) in 40 steps from 2‐bromo‐5‐methoxyphenethyl iodide. Key steps in the construction of the architecturally complex polycyclic structure of this natural product were a radical cyclization of an enyne and a palladium‐catalyzed intramolecular α arylation of an aldehyde.

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“…This work served as a prelude to an explosion of research pertaining to the remote functionalization of steroids, from the work of Barton 32a-d and Breslow 32e-g in the 1960s and 1970s to dozens of research groups presently. The logic of this timeless approach has been featured in recent syntheses and studies, including Shibanuma’s strategy toward kobusine 34 and Giannis’ cyclopamine ( 9 ) synthesis. 25 …”

Section: Steroid-alkaloidsmentioning

confidence: 99%

Terpenoid‐Alkaloids: Their Biosynthetic Twist of Fate and Total Synthesis

Cherney

Baran

2011

Israel Journal of Chemistry

101

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Terpenes and alkaloids are ever-growing classes of natural products that provide new molecular structures which inspire chemists and possess a broad range of biological activity. Terpenoid-alkaloids originate from the same prenyl units that construct terpene skeletons. However, during biosynthesis, a nitrogen atom (or atoms) is introduced in the form of β-aminoethanol, ethylamine, or methylamine. Nitrogen incorporation can occur either before, during, or after the cyclase phase. The outcome of this unique biosynthesis is the formation of natural products containing unprecedented structures. These complex structural motifs expose current limitations in organic chemistry, thus providing opportunities for invention. This review focuses on total syntheses of terpenoid-alkaloids and unique issues presented by this class of natural products. More specifically, it examines how these syntheses relate to the way terpenoid-alkaloids are made in Nature. Developments in chemistry that have facilitated these syntheses are emphasized, as well as chemical technology needed to conquer those that evade synthesis.

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Synthetic approach to diterpene alkaloids: Construction of the bridged azabicyclic ring system of kobusine.

Cited by 30 publications

References 0 publications

Asymmetric Synthetic Access to the Hetisine Alkaloids: Total Synthesis of (+)‐Nominine

Asymmetric Synthetic Access to the Hetisine Alkaloids: Total Synthesis of (+)‐Nominine

Total Synthesis of (±)‐Nominine, a Heptacyclic Hetisine‐Type Aconite Alkaloid

Terpenoid‐Alkaloids: Their Biosynthetic Twist of Fate and Total Synthesis

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