Manganese-mediated novel dibromination of olefins with tetradecyltrimethylammonium permanganate and trimethylbromosilane

Hazra, Banasri; Chordia, Mahendra D.; Bahule, B. B.; Pore, Vandana S.; Basu, Sourav

doi:10.1039/p19940001667

Cited by 17 publications

(10 citation statements)

References 9 publications

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“…186 With Me 3 SiBr in place of Me 3 SiCl, the latter reagent system has also been employed for the anti -selective dibromination of alkenes. 187 The use of BnNEt 3 MnO 4 with (COCl) 2 or Me 3 SiCl as promoters has also been extended to the vicinal dichlorination of allenes. 188 …”

Section: Alkene Dihalogenations With Transition Metal Halides As Rmentioning

confidence: 99%

“…[186] With Me 3 SiBr in place of Me 3 SiCl, the latter reagent system has also been employed for the antiselective dibromination of alkenes. [187] Theu se of BnNEt 3 MnO 4 with (COCl) 2 or Me 3 SiCl as promoters has also been extended to the vicinal dichlorination of allenes. [188] Markó et al have suggested that chloriranium ions (arising either from molecular Cl 2 or some other Cl + equivalent) are unlikely to be intermediates in these manganese(VII)-mediated dichlorinations.S pecifically,d ifferent product distributions are observed for the dichlorination of cyclooctadiene monoepoxide 77 with either Cl 2 (in CH 2 Cl 2 at 20 8 8C) or Markós reagent [using either (COCl) 2 at À40 8 8C [32b] or Me 3 SiCl at 0!20 8 8C.…”

Section: Angewandte Reviewsmentioning

confidence: 99%

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Catalytic, Stereoselective Dihalogenation of Alkenes: Challenges and Opportunities

2015

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Although recent years have witnessed significant advances in the development of catalytic, enantioselective halofunctionalizations of alkenes, the related dihalogenation of olefins to afford enantioenriched vicinal dihalide products remains comparatively underdeveloped. However, the growing number of complex natural products bearing halogen atoms at stereogenic centers has underscored this critical gap in the synthetic chemist's arsenal. This Review highlights the selectivity challenges inherent in the design of enantioselective dihalogenation processes, and formulates a mechanism-based classification of alkene dihalogenations, including those that may circumvent the "classical" haliranium (or alkene-dihalogen π-complex) intermediates. A variety of metal and main group halide reagents that have been used for the dichlorination or dibromination of alkenes are discussed, and the proposed mechanisms of these transformations are critically evaluated. AbstractCatalysis of alkene dihalogenation , under different activation modes, with control over both the absolute and relative stereochemical course of dihalogen addition, is one of the most vexing problems in stereoselective synthesis. Dihalogenations that circumvent the "classical" haliranium (or alkene-dihalogen π complex) intermediates provide new and exciting opportunities for catalysis, potentially having broader implications for the design of stereoselective alkene difunctionalizations.

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Section: Alkene Dihalogenations With Transition Metal Halides As Rmentioning

confidence: 99%

Section: Angewandte Reviewsmentioning

confidence: 99%

Catalytic, Stereoselective Dihalogenation of Alkenes: Challenges and Opportunities

2015

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“…Eine ähnliche Vorschrift wurde auch von Hazra und Pore berichtet, die Tetradecyltrimethylammoniumpermanganat (H 29 C 14 NMe 3 MnO 4 ) als eine “sichere” Alternative zu (isoliertem) BnNEt 3 MnO 4 einsetzten (H 29 C 14 NMe 3 MnO 4 detoniert nicht beim Trocknen des festen Reagens bei erhöhten Temperaturen) 186. Mit Me 3 SiBr anstelle von Me 3 SiCl wurde das zuletzt genannte Reagentiensystem auch für die anti ‐selektive Dibromierung von Alkenen benutzt 187. Die Verwendung von BnNEt 3 MnO 4 mit (COCl) 2 oder Me 3 SiCl als Promotoren wurde außerdem für die vicinale Dichlorierung von Allenen verwendet 188…”

Section: Alken‐dihalogenierungen Mit üBergangsmetallhalogeniden Alunclassified

Katalytische stereoselektive Dihalogenierung von Alkenen: Herausforderungen und Chancen

2015

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Während in den letzten Jahren signifikante Fortschritte bei der Entwicklung katalytischer, enantioselektiver Halogenfunktionalisierungen von Alkenen erzielt wurden, ist die verwandte Dihalogenierung von Olefinen zur Bildung enantiomerenangereicherter vicinaler dihalogenierter Produkte vergleichsweise unterentwickelt. Allerdings verweist die steigende Anzahl komplexer Naturstoffe mit Halogenatomen an stereogenen Zentren deutlich auf diese Lücke im Arsenal der Synthesechemie. Dieser Aufsatz behandelt die Herausforderungen bei der gezielten Entwicklung enantioselektiver Dihalogenierungsprozesse und formuliert eine mechanismusbasierte Klassifizierung der Dihalogenierung von Alkenen, einschließlich solcher, welche die “klassischen” Haliranium‐Intermediate (oder Alkendihalogen‐π‐Komplexe) umgehen können. Die Anwendung zahlreicher Metall‐ und Hauptgruppenhalogenide als Reagentien zur Dichlorierung oder Dibromierung von Alkenen wird diskutiert, und die vorgeschlagenen Mechanismen dieser Transformationen werden kritisch beurteilt.

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“…The usual way to achieve such an oxirane ring at this position is through the oxidation of a double bond at C1. This synthetic step is generally performed using OsO 4 , but because it is an expensive, dif®cult to handle and hazardous material, we changed to permanganate ammonium salts, according to reports on the use of these reagents as oxidants (Bhushan et al, 1984;Hazra et al, 1994;Hazra et al, 1997). By applying this synthetic step to (25R)-5-spiro-2-ene-6-one, we obtained the expected 2,3-dihydroxy derivative, but also a by-product, (I), which was identi®ed by its crystal structure as (25R)-1,2-epoxy-3-hydroxy-5-spirostan-6-one (see Experimental).…”

Section: Commentmentioning

confidence: 99%

(25R)-1α,2α-Epoxy-3α-hydroxy-5α-spirostan-6-one

2004

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Manganese-mediated novel dibromination of olefins with tetradecyltrimethylammonium permanganate and trimethylbromosilane

Cited by 17 publications

References 9 publications

Catalytic, Stereoselective Dihalogenation of Alkenes: Challenges and Opportunities

Catalytic, Stereoselective Dihalogenation of Alkenes: Challenges and Opportunities

Katalytische stereoselektive Dihalogenierung von Alkenen: Herausforderungen und Chancen

(25R)-1α,2α-Epoxy-3α-hydroxy-5α-spirostan-6-one

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