Cyclopropane-shift type reaction of diaryl(2-halogenocyclopropyl)methanols promoted by Lewis acids

Wakasugi, Kazunori; Nishii, Yoshinori; Tanabe, Yoo

doi:10.1016/s0040-4039(00)00979-5

Cited by 14 publications

(6 citation statements)

References 5 publications

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“…Many observations are consistent with a radical mechanism; however, two-electron processes cannot be excluded. 347 Similar monodechlorination results were obtained for gem-dichlorocyclopropanes using methylmagnesium bromide or tert-butylmagnesium chloride and the catalyst Co(dppe)Cl 2 348,349 (eq 64). 348 gem-Dihalocyclopropanes bearing a neighboring hydroxymethyl group underwent highly stereoselective reductions, giving anti-monochlorides.…”

Section: Iv1 Reductive Dehalogenation Of Gem-dihalocyclopropanessupporting

confidence: 58%

Syntheses ofgem-Dihalocyclopropanes and Their Use in Organic Synthesis

2003

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Section: Iv1 Reductive Dehalogenation Of Gem-dihalocyclopropanessupporting

confidence: 58%

Syntheses ofgem-Dihalocyclopropanes and Their Use in Organic Synthesis

2003

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“…Many modern methods for the synthesis of naphthalene frameworks using several transition metal catalysts, such as Pd, W, Rh, Ru, and Ir, have been reported. However, little attention has been paid to the Lewis acid-catalyzed benzannulation, , while a large amount of research has been carried out for the Lewis acid-catalyzed [4+2] Diels−Alder reaction . Recently, we have communicated the AuCl 3 -catalyzed formal [4+2] benzannulation between o -alkynyl(oxo)benzenes 1 and alkynes, which produces naphthyl ketones in good to high yields (eq 1) …”

Section: Introductionmentioning

confidence: 99%

Lewis Acid-Catalyzed Benzannulation via Unprecedented [4+2] Cycloaddition of o-Alkynyl(oxo)benzenes and Enynals with Alkynes

et al. 2003

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The reaction of o-alkynyl(oxo)benzenes 1 with alkynes 2 in the presence of a catalytic amount of AuCl(3) in (CH(2)Cl)(2) at 80 degrees C gave the [4+2] benzannulation products, naphthyl ketone derivatives 3 and 4, in high yields. When the reaction was carried out using AuBr(3) instead of AuCl(3), the reaction speed was enhanced and the chemical yield was increased. On the other hand, when the reaction was carried out in the presence of a catalytic amount of Cu(OTf)(2) and 1 equiv of a Brønsted acid, such as CF(2)HCO(2)H, in (CH(2)Cl)(2) at 100 degrees C, the decarbonylated naphthalene products 5 were obtained in high yields. Similarly, the Cu(OTf)(2)-H(2)O-promoted reaction of the enynals 7 with an alkyne 2 afforded the corresponding [4+2] benzannulation products, decarbonylated benzene derivatives 8, in good yields. Both AuX(3)- and Cu(OTf)(2)-catalyzed benzannulations proceed most probably through the formation of the benzo[c]pyrylium ate complex 10, the Diels-Alder addition of alkynes 2 to the ate complex, and the resulting bicyclic pyrylium ion intermediate 12. The mechanistic difference between the AuX(3) and Cu(OTf)(2)-HA system is discussed.

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“…Highly substituted naphthalenes are common structural units in numerous biologically significant natural products and pharmaceuticals, and improved methods for their construction are highly desirable. − Among the most important synthetic routes to such compounds are annulation via Fischer carbenes (the Dötz reaction) 3 and the palladium-catalyzed cyclization of alkynes by arylsilyl triflates via in situ generation of highly reactive benzynes . Another method of synthesis is based on the cyclopropane-shift reaction of diaryl(2-halogenocyclopropyl)methanols . Very recently, substituted naphthalenes have been prepared using the gallium-catalyzed cyclization of carbonyl compounds or epoxides with alkynes…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Substituted Naphthalenes and Carbazoles by the Palladium-Catalyzed Annulation of Internal Alkynes

Huang

Larock

2003

J. Org. Chem.

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An efficient synthesis of highly substituted naphthalenes has been developed by the palladium-catalyzed annulation of a variety of internal alkynes, in which two new carbon-carbon bonds are formed in a single step under relatively mild reaction conditions. This method has also been used to synthesize carbazoles, although a higher reaction temperature is necessary. The process involves arylpalladation of the alkyne, followed by intramolecular Heck olefination and double-bond isomerization. This method accommodates a variety of functional groups and affords the anticipated highly substituted naphthalenes and carbazoles in good to excellent yields.

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Cyclopropane-shift type reaction of diaryl(2-halogenocyclopropyl)methanols promoted by Lewis acids

Cited by 14 publications

References 5 publications

Syntheses ofgem-Dihalocyclopropanes and Their Use in Organic Synthesis

Syntheses ofgem-Dihalocyclopropanes and Their Use in Organic Synthesis

Lewis Acid-Catalyzed Benzannulation via Unprecedented [4+2] Cycloaddition of o-Alkynyl(oxo)benzenes and Enynals with Alkynes

Synthesis of Substituted Naphthalenes and Carbazoles by the Palladium-Catalyzed Annulation of Internal Alkynes

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