Asymmetric homogeneous hydrogenation with rhodium(I) complexes of chiral phosphines

Morrison, J. D.; Burnett, Robert E.; Aguiar, Adam M.; Morrow, Cary J.; Phillips, Carol

doi:10.1021/ja00734a066

Cited by 156 publications

(34 citation statements)

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“…Initial attempts to react (E)-2 by using bisphosphine ligands (L1-L4) [27][28][29] gave poor selectivity, though these ligands have been shown to be effective for normal enantioselective Heck reactions (entries 1-4). 14) Representative optically active monophosphines, (R)-MeO-MOP (L5) 30) and (ϩ)-NMDPP (L6), 31) did not improve the selectivity (entries 5, 6). However, when the reaction was performed with phosphoramidite L7 32) that was synthesized from (R)-BINOL and bis[(R)-1-phenylethyl]amine, piperidone (R)-1 was isolated in 52% and the selectivity reached to 43% ee (entry 7).…”

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confidence: 98%

Toward General Access to the <i>Aspidosperma</i>-Type Terpenoid Indole Alkaloids: Synthesis of the Key 3,3-Disubstituted Piperidones through Enantioselective Intramolecular Heck-Type Reaction of Chloroformamides

Yasui

Takeda

Takemoto

2008

CHEMICAL & PHARMACEUTICAL BULLETIN

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An enantioselective intramolecular Heck-type reaction of chloroformamides has been developed for the synthesis of 3,3-disubstituted piperidones. The desired piperidone was formed in the presence of a palladium catalyst, an optically active phosphoramidite ligand, K 3 PO 4 and Ag 3 PO 4 . The obtained piperidone was converted to epieburnamonine.Key words enantioselective reaction; total synthesis; terpenoid indole alkaloid Chem. Pharm. Bull. 56(11) 1567-1574 (2008) © 2008 Pharmaceutical Society of Japan * To whom correspondence should be addressed. e-mail: takemoto@pharm.kyoto-u.ac.jp under normal conditions (entries 1-3). However, lactam 9 was isolated in 60% yield when Ag 3 PO 4 was added to the reaction (entry 4). The combination of Pd 2 (dba) 3 and BINAP was also able to promote the cyclization in the presence of Ag 3 PO 4 (entry 5). Nolan's NHC catalyst was not effective (entry 6).With these results in hand, syntheses of each cis-trans isomer of alkenyl chloroformamide 2 were performed. Alkene (E)-4 was synthesized through hydroalumination as a key step (Fig. 5). 4-Pentyn-1-ol (10) was transformed into alcohol 11 through oxidation, acetalization, and hydroxymethylation using benzotriazolylmethanol (BtCH 2 OH). 22) Alcohol 11 was then subjected to the hydroalumination-iodination sequence 23,24) to give (Z)-iodo alkene 12, whose configuration was confirmed by NOE experiment. Ethylation by Suzuki coupling, followed by benzylation gave the desired alkene (E)-4.Change of the starting material afforded the alternative stereoisomer (Fig. 6). (Z)-Iodoalkene 14 was synthesized from 2-pentyn-1-ol (13) through hydroalumination and iodination. Since benzylation of the hydroxy group under either basic or acidic conditions competed with decomposition of the starting material, protection by THP group was carried out. The resultant THP ether 15 underwent Negishi coupling with 3,3-(dimethoxy)propylzinc chloride 16. 25) Selective hydrolysis of the THP ether and benzylation afforded the desired alkene (Z)-4.Alkenyl acetals (E)-4 and (Z)-4 were coupled with tryptamine 3 26) through hydrolysis and reductive amination to give amines (E)-17 and (Z)-17, respectively (Fig. 7). These compounds were converted to the corresponding chloroformamides (E)-2 and (Z)-2 by treating with triphosgene and Et 3 N.Before the enantioselective Heck-type reaction, a racemic reaction was attempted to find out a suitable palladium source ( Table 2). The cyclized product 1 was isolated after hydrolysis of the resultant enol ether. At the early stage, poor reproducibility was a serious problem. After several attempts, it was found that the activity of the catalyst is highly associated with the conditions used to mix palladium sources and ligands prior to the addition of chloroformamide 2. When [Pd(h 3 -C 3 H 5 )Cl] 2 was premixed with (p-tol) 3 P at 30°C for 30 min, the disappearance of 2 was slow and the yield was 30% after 24 h (entry 1). In contrast, the starting material disappeared in 3 h and yield reached 49% when premixing was performed at 40°C...

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Toward General Access to the <i>Aspidosperma</i>-Type Terpenoid Indole Alkaloids: Synthesis of the Key 3,3-Disubstituted Piperidones through Enantioselective Intramolecular Heck-Type Reaction of Chloroformamides

Yasui

Takeda

Takemoto

2008

CHEMICAL & PHARMACEUTICAL BULLETIN

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“…In den Publikationen von Knowles [17] und Horner [18] aus dem Jahr 1968 handelte es sich bei den Katalysatoren um Varianten des Wilkinson-Katalysators [(Ph 3 P) 3 RhCl], in denen die Triphenylphosphanliganden durch chirale Methylpropylphenylphosphane (MPPP) ersetzt waren (Schema 1). Die Enantiomerenüberschüsse in diesen frühen Studien waren mäßig (< 30 % ee), [19] bevor dann im Jahr 1971 Morrison et al [20] über eine verbesserte Selektivität (bis 61 % ee bei der Reduktion der b-Methylzimtsäure) mit Neomenthyldiphenylphosphan (NMDPP) berichteten (Schema 1). Kurioserweise glaubte man in den frühesten Tagen der homogenen Hydrierung, dass zweizähnige Diphosphane als Liganden ungeeignet wären.…”

Section: "Effiziente Asymmetrische Hydrierungen Erfordern (Zweizähnigunclassified

“…Zunächst boten solch einfache Liganden den mçglichen Vorteil einer einfacheren Synthese. Zwar erforderten die frühesten Liganden, die eine P-zentrierte Chiralität aufwiesen, aufwän-dige Synthesen, doch zeigten Morrison et al 1971 durch den einfachen Aufbau von NMDPP, dass dies nicht der Fall sein brauchte. [20] Zweitens kann festgestellt werden, dass Monsanto der Kommerzialisierung der l-DOPA-Synthese mit einem einzähnigen Liganden nahekam.…”

Section: "Effiziente Asymmetrische Hydrierungen Erfordern (Zweizähnigunclassified

“…Zwar erforderten die frühesten Liganden, die eine P-zentrierte Chiralität aufwiesen, aufwän-dige Synthesen, doch zeigten Morrison et al 1971 durch den einfachen Aufbau von NMDPP, dass dies nicht der Fall sein brauchte. [20] Zweitens kann festgestellt werden, dass Monsanto der Kommerzialisierung der l-DOPA-Synthese mit einem einzähnigen Liganden nahekam. Dieser Ligand, CAMP (Schema 1), ermçglichte die Hydrierung (Schema 2) mit bis zu 88 % ee; die mit DiPAMP beobachtete Selektivität lag mit 95 % ee nur geringfügig hçher.…”

Section: "Effiziente Asymmetrische Hydrierungen Erfordern (Zweizähnigunclassified

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Black‐Swan‐Ereignisse in der organischen Synthese

Nugent

2012

Angewandte Chemie

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Verbreitet sich ein Forschungsgebiet „wie ein Virus“, geht dies zumeist mit Veränderungen in der Lehrmeinung einher. Oft finden sich dann in der älteren Literatur nachträglich Indizien, dass die konventionelle Vorstellung nicht richtig sein konnte. Diese Antezedentien werden als „Black‐Swan“‐Ereignisse bezeichnet. Das Bild zeigt die virusartige Verbreitung der Forschungen zur homogenen Goldkatalyse.

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“…Knowles and Sabacky and Horner et al, as well as other pioneering scientists, such as Mislow and Korpiun, 16 Kagan et al, 17,18 Morrison et al, 19 and Bosnich and Fryzuk, [20][21][22] opened a door to an "asymmetric hydrogenation"-a new, exciting, and important field for both academic and industrial research. For two decades, homogeneous asymmetric hydrogenation has been dominated by Rh(I)-based catalysts of prochiral olefins.…”

Section: Introductionmentioning

confidence: 99%

Stereoselective Hydrogenation ofCCBonds: Application to Drug and Natural Product Synthesis

Andrushko

2013

Stereoselective Synthesis of Drugs and Natural Products

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Asymmetric homogeneous hydrogenation is perhaps one of the most researched areas in homogeneous catalysis; thus, it is now used in numerous innovative applications in stereoselective syntheses of many chiral pharmaceutical and natural products. Metal complexes, derived from transition metals, like Rh, Ru, Ir, and so on, and chiral ligands (usually mono‐ or diphosphine ligands), are widely used as catalysts in asymmetric alkene hydrogenation as a result of their efficiency in the preparation of enantiopure compounds with excellent atom economy. This chapter provides many interesting examples of homogeneous enantio‐ and diastereoselective hydrogenation of CC bonds, highlighting the utility of these methods as useful synthetic tools for the construction of stereogenic centers in stereoselective drug and natural product syntheses.

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Asymmetric homogeneous hydrogenation with rhodium(I) complexes of chiral phosphines

Cited by 156 publications

References 2 publications

Toward General Access to the <i>Aspidosperma</i>-Type Terpenoid Indole Alkaloids: Synthesis of the Key 3,3-Disubstituted Piperidones through Enantioselective Intramolecular Heck-Type Reaction of Chloroformamides

Toward General Access to the <i>Aspidosperma</i>-Type Terpenoid Indole Alkaloids: Synthesis of the Key 3,3-Disubstituted Piperidones through Enantioselective Intramolecular Heck-Type Reaction of Chloroformamides

Black‐Swan‐Ereignisse in der organischen Synthese

Stereoselective Hydrogenation ofCCBonds: Application to Drug and Natural Product Synthesis

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