A New Route to Nezukone

Hayakawa, Yoshihiro; Sakai, Michiko; Noyori, Ryoji

doi:10.1246/cl.1975.509

Cited by 20 publications

(4 citation statements)

References 4 publications

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“…As already noted for the work of Fort, − the cycloaddition of allyl cations with furans is useful for the preparation of 8-oxabicyclo[3.2.1]oct-6-en-3-ones, which are widely used starting materials for the synthesis of such natural products as analogues of thromboxane A 2 and B 2 , C-nucleosides, muscarine analogues, pyrrolizidine alkaloids, and troponoids. ,− Thus, reaction of 9 with furan provides good yields of 10 and 11 together with trace amounts of 12 , which either derives from a stepwise process or from trace amounts of the syn,anti allyl cation . With increasing electrophilicity of the oxyallyl cation, however, there is considerable loss of stereoselectivity observed for the reaction, suggesting a class B process .…”

Section: Introductionmentioning

confidence: 93%

Quantum Chemical Characterization of Cycloaddition Reactions between the Hydroxyallyl Cation and Dienes of Varying Nucleophilicity

Cramer

Barrows

1998

J. Org. Chem.

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Hydroxyallyl cation prefers to undergo cycloaddition reactions with dienes in a stepwise fashion. Analysis of positive charge distribution in the intermediate formed after initial C−C bond formation provides a simple unifying method for rationalizing changes in reactivity as a function of diene nucleophilicity. Predicted product distributions are consistent with results from experimental studies. Interestingly, for the initial intermediate generated from 1,3-butadiene, [3 + 2] cycloaddition reactions are favored, but closure to form a C−O bond as the second step results in an intermediate that can undergo a low-energy Claisen rearrangement to form a seven-membered-ring product identical to that expected from compact [4 + 3] cycloaddition.

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Section: Introductionmentioning

confidence: 93%

Quantum Chemical Characterization of Cycloaddition Reactions between the Hydroxyallyl Cation and Dienes of Varying Nucleophilicity

Cramer

Barrows

1998

J. Org. Chem.

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“…Synthesis of tropolone [31], 3-methoxytropolone, and isopygmaein [32], various -tropolone derivatives [33], -dolabrin, -thujaplicin, 7-methoxy-4-isopropyltropolone, and -thujaplicinol [34] has been explored. Many synthetic methods for nezukone have been developed [35,36,37]. Tropolone derivatives [38,39], benzotropolone derivatives, or benzotropone endoperoxides [40], have been synthesized and chemical and physical properties of tropone and tropolones were studied [41].…”

Section: Chemical Synthesis and Modification Of Troponoidsmentioning

confidence: 99%

Plant Troponoids: Chemistry, Biological Activity, and Biosynthesis

Zhao

2007

CMC

113

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Tropone or tropolone and its derivatives (here together called troponoids) belong to a family of natural products with a seven-membered aromatic ring and various side groups. They are mainly synthesized by plants and fungi, and most troponoids play roles of antibacterial defenses in these organisms. With an increasingly severe situation of antibiotic resistant bacteria, as well as a requirement for antifungal medicines, troponoids have attracted extensive studies since they have powerful antibacterial and antifungal activity, particularly against antibiotic-resistant bacteria. In addition, many other biological activities such as antiviral, antitumor, antioxidant, anti-inflammatory, insecticidal, or enzyme inhibitor activities are associated with troponoids. After extensive studies in the 1960s-70s, interests in natural troponoids dedclined. However, chemical and biomedical studies on troponoids bloom again from the 1990s. To date great progress has been made with troponoid study in terms of identification of new natural troponoids, chemical synthesis and properties, biological activity, biosynthesis and metabolism. Particularly, bioassay-guided screening strategy and structure-activity relation-directed structure modification and drug design has resulted in the synthesis and discovery of many new derivatives. Many of them have great promise to be developed into new medicines for their potent and specific activities. This review presents the recent advances in troponoid studies and highlights multiple faceted biological activities of troponoids, as well as their relationships with chemical structures. Chemistry, biosynthesis, and production via biotechnology of troponoids are also briefly reviewed. Applications of troponoids in daily life, agriculture, medicine, and industry, and the related patents have been considered to further extend our understanding of the increasing impact of troponoids on humans.

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“…240–241 The synthesis of the latter is shown in Scheme 67. An iron-promoted oxyallylcation [4+3] cycloaddition between tetrabromoketone 67-1 and 2- iso -propyl furan 67-3 provided the seven-membered ring in 67-4 with an oxygen bridge.…”

Section: Synthesis Of Naturally Occurring Tropones and Tropolonesmentioning

confidence: 99%

Synthesis of naturally occurring tropones and tropolones

et al. 2014

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Tropones and tropolones are an important class of seven-membered non-benzenoid aromatic compounds. They can be prepared directly by oxidation of seven-membered rings. They can also be derived from cyclization or cycloaddition of appropriate precursors followed by elimination or rearrangement. This review discusses the types of naturally occurring tropones and tropolones and outlines important methods developed for the synthesis of tropone and tropolone natural products.

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A New Route to Nezukone

Abstract: A simple synthesis of nezukone based on the iron carbonyl-promoted coupling between α,α,α′,α′-tetrabromoacetone and 3-isopropylfuran is described.

Cited by 20 publications

References 4 publications

Quantum Chemical Characterization of Cycloaddition Reactions between the Hydroxyallyl Cation and Dienes of Varying Nucleophilicity

Quantum Chemical Characterization of Cycloaddition Reactions between the Hydroxyallyl Cation and Dienes of Varying Nucleophilicity

Plant Troponoids: Chemistry, Biological Activity, and Biosynthesis

Synthesis of naturally occurring tropones and tropolones

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