Carbon-carbon bond formation promoted by transition metal carbonyls. 18. New synthesis of troponoid compounds via the iron carbonyl promoted cyclocoupling between polybromo ketones and 1,3-dienes

Takaya, Hidemasa; Hayakawa, Yoshihiro; Makino, Shio; Noyori, Ryoji

doi:10.1021/ja00474a020

Cited by 65 publications

(20 citation statements)

References 22 publications

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“…Schemes 24 and 25). 415,416,420,[657][658][659][660][661][662][663][664][665] in particular have strongly contributed to the development of the methodology. The use of Fe 2 (CO) 9 to reductively dehalogenate the R,R′-dibromo ketones has the advantage that through coordination to iron, a great variety of oxyallyl cations 180 (cf.…”

Section: [4+3]mentioning

confidence: 99%

Metal-Assisted Cycloaddition Reactions in Organotransition Metal Chemistry

1997

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Section: [4+3]mentioning

confidence: 99%

Metal-Assisted Cycloaddition Reactions in Organotransition Metal Chemistry

1997

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“…As a precursor for an oxyallyl intermediate, which would be interesting for incorporation of the isopropyl side chain into terpenoids, [15][16][17] we investigated the reaction of 1a with TFE/NaTFE in the presence of furan. Monitoring the run by GLC, we observed a small peak in the range characteristic of [4+3] cycloadducts (t R = 11.4 min, 5 %), but we could not isolate this component.…”

Section: Resultsmentioning

confidence: 99%

“…In order to gather more data for comparison of the NMR spectra of these oxabicycles, thus securing structures, we subjected 36 and endo-endo-34 to the well-known dehalogenation procedure with a zinc-copper couple, [15] which afforded oxabicycles 35 and 37, respectively. Noyori et al has described a 2-isopropyl-8-oxabicyclo[3.2.1]oct-6-en-3-one (unspecified configuration) obtained from 1,1,3-tribromo-4-methylpentan-2-one and furan by reduction with nonacarbonyldiiron, followed by dehalogenation with a zinc-copper couple (35 % yield over these two steps).…”

Section: A 27a)mentioning

confidence: 99%

Base‐Induced Trifluoroethanolysis of Acyclic Di‐ and Trihalogeno Ketones: Favorskii Rearrangement and [4+3] Cycloaddition

Föhlisch¹,

Franz²,

Kreiselmeier³

2005

Eur J Org Chem

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Reactions of five acyclic dihalogeno‐ and trihalogeno ketones, representing the α,α‐, α,α′‐, α,α,α‐ and α,α,α′‐di‐ and trihalogeno substitution pattern, with sodium 2,2,2‐trifluoroethoxide in 2,2,2‐trifluoroethanol (NaTFE/TFE) in the presence of furan were investigated with the aim of obtaining [4+3] cycloadducts of the corresponding oxyallyl intermediates. Preference of Favorskii rearrangement over cycloaddition was observed with dichloromethyl isobutyl ketone (1a) and 1,3‐dibromobutan‐2‐one (12) that formed mainly the trifluoroethyl esters of 3‐chloro‐2‐isopropylpropanoic acid (9a), and (Z)‐but‐2‐enoic acid (isocrotonic acid) (13), respectively. 9a was dehydrohalogenated to form trifluoroethyl 3‐isopropylacrylate (11a). [4+3] Cycloaddition was favored with the 1,1,3‐trihalogenobutan‐2‐ones 24 and 25, leading to 2,4‐dihalogenated 8‐oxabicyclo[3.2.1]oct‐6‐en‐3‐ones (26, 27) as a mixture of endo‐exo‐stereoisomers. With trichloromethyl isobutyl ketone (30) the isomeric 2,4‐dichloro‐substituted oxabicycles (34) were formed in lithium perchlorate/diethyl ether/furan/triethylamine, while in NaTFE/TFE solvolytic displacement of one chloro substituent occurred, providing 2‐chloro‐4‐trifluoroethoxy‐4‐isopropyl‐8‐oxabicyclo[3.2.1]oct‐6‐en‐3‐one (36). By analogy, 27 reacted with sodium methoxide/methanol to form the methoxy‐substituted oxabicycles 39a and 39b. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)

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“…Outro método para a obtenção de troponas alquiladas, desenvolvido por Takaya et alii 65 , envolve o tratamento de cicloeptenonas com hidrotribrometo de pirrolidona, seguido de aquecimento com LiCl/DMF. Nestes casos as cicloeptenonas são obtidas pela cicloadição entre dienos acíclicos e polibromocetonas, na presença de Fe 2 (CO) 9 .…”

Section: Estudos Visando a Obtenção De Lactonas Sesquiterpênicasunclassified

“…O dieno pode também ser utilizado na forma de um complexo com Fe(CO) 3 . Um exemplo ilustrativo dessa metodologia é apresentado no esquema 26 65 . …”

Section: Estudos Visando a Obtenção De Lactonas Sesquiterpênicasunclassified

Cicloadições [3+4] via cátions oxialílicos: aplicações em sínteses orgânicas

Demuner¹,

Barbosa²,

Piló‐Veloso³

1997

Quím. Nova

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Em seu experimento clássico, Fort 3-5 tratou 1-cloro-1,3-difenilpropanona (1), furano e 2,6-lutidina em DMF, obtendo uma mistura isomérica dos cicloadutos 2a e 2b. Quando essa reação foi repetida em presença de metanol, obteve-se somente o produto 3, proveniente da substituição do cloro da cetona 1 (Esquema 1). Fort realizou o estudo da cinética dessa metanó-lise e verificou que, neste caso, a formação do composto 3 ocorre através do intermediário 4, o qual pode ser originado a partir do cátion oxialílico 5, conforme ilustrado no esquema 2. Esquema 1 Esquema 2Mais tarde, Cookson et alii 6,7 desenvolveram outro procedimento mais eficiente para o preparo dos oxabiciclos 2a e 2b através da redução da α,α'-dibromocetona 6 com NaI, na presença de furano (Esquema 3). Neste caso foi observada a formação de grande quantidade da furilcetona 2c, resultante da reação de substituição eletrofílica entre o furano e o cátion oxialílico gerado in situ.Para avaliar a generalidade desta cicloadição Cookson et alii 7 realizaram experimentos com ciclopentadieno e Nmetilpirrol cujos resultados (compostos 7a-b e 8) são mostrados no esquema 3. No caso do N-metilpirrol apenas o produto da substituição eletrofílica 8 foi isolado.Em termos eletrônicos, de acordo com as regras de Woodward-Hoffmann, essa reação é uma cicloadição iônica do

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Carbon-carbon bond formation promoted by transition metal carbonyls. 18. New synthesis of troponoid compounds via the iron carbonyl promoted cyclocoupling between polybromo ketones and 1,3-dienes

Cited by 65 publications

References 22 publications

Metal-Assisted Cycloaddition Reactions in Organotransition Metal Chemistry

Metal-Assisted Cycloaddition Reactions in Organotransition Metal Chemistry

Base‐Induced Trifluoroethanolysis of Acyclic Di‐ and Trihalogeno Ketones: Favorskii Rearrangement and [4+3] Cycloaddition

Cicloadições [3+4] via cátions oxialílicos: aplicações em sínteses orgânicas

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