Studies toward Total Synthesis of Non-Aromatic Erythrinan Alkaloids. 7. Synthesis of Cocculolidine Skeleton.

Mohri, Kunihiko; Isobe, Kimiaki; Maeda, M.; Takeda, Taroh; Ohkubo, Ryoko; Tsuda, Yoshisuke

doi:10.1248/cpb.46.1872

Cited by 6 publications

(3 citation statements)

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“…Oxidative cleavage of aromatic rings is widespread in nature but is limited in the laboratory because of the difficulty in controlling the reaction. Our group reported that ozonolytic cleavage of o -dimethoxybenzenes to muconates was satisfactorily controlled by addition of BF 3 -etherate as a regulator . This oxidation reaction was applied to the aromatic erythrinan compound 11 , which was derived from alcohol 6 by treatment with methanesulfonyl chloride (Scheme ).…”

Section: Resultsmentioning

confidence: 99%

Biomimetic Total Synthesis of (±)-8-Oxoerymelanthine

Yoshida¹,

Mohri²,

Isobe³

et al. 2009

J. Org. Chem.

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Erymelanthine 1 and 8-oxoerymelanthine 2 are unique erythrina alkaloids containing a pyridine ring. We synthesized (+/-)-8-oxoerymelanthine 2 in 2.0% overall yield using the following key reactions. The characteristic 6-5-6-6-membered ring system was constructed by the stereoselective intermolecular Diels-Alder reaction. Oxidative cleavage of the aromatic D-ring was conducted chemo- and regioselectively by ozonolysis in the presence of BF(3)-etherate. This cleavage site is identical to the site cleaved during the biosynthesis of erymelanthine 1. Nitrogen incorporation was achieved by aminolysis. Conversion of the D-ring pyridone to the corresponding pyridine was efficiently accomplished by palladium-catalyzed reduction of aryl triflate 21. This is not only the first total synthesis of (+/-)-8-oxoerymelanthine 2 (where the D-ring is pyridine) but also, more importantly, a biomimetic total synthesis of an erythrinan D-aza alkaloid.

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Section: Resultsmentioning

confidence: 99%

Biomimetic Total Synthesis of (±)-8-Oxoerymelanthine

Yoshida¹,

Mohri²,

Isobe³

et al. 2009

J. Org. Chem.

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“…417 The synthetic erythrinane 232 has been oxidised by cerium(IV) methanesulfonate to the quinone 233, ozonolysis of which afforded 234, and this was reduced to the lactone 235 which has the skeleton of the alkaloid cocculolidine 236. 418…”

Section: Colchicine and Related Alkaloidsmentioning

confidence: 99%

β-Phenylethylamines and the isoquinoline alkaloids (July 1998 to June 1999)

Bentley

2000

Nat. Prod. Rep.

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“…Thus, erythraline is an example of an aromatic erythrinan alkaloid and isophellibiline is a member of the nonaromatic homoerythrinan subclass. The majority of synthetic work has been devoted to the aromatic erythrinan subclass of compounds, and a number of syntheses have been recorded. , Most of the syntheses take advantage of a facile C(5)−C(13) ring closure, most commonly by attack of an electron-rich aromatic ring upon an N -acyliminium ion intermediate. , Consequently, the synthesis of the nonaromatic erythrinan subclass can be viewed as significantly more challenging, and accordingly, only two of these natural products, cocculolidine 3d and β-erythroidine,3e have been synthesized. In addition, the erythrina alkaloids exhibit an interesting pharmacology, including sedative, hypotensive, neuromuscular blocking, and CNS activity .…”

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confidence: 99%