A rapid and efficient cycloaddition of simple imines with activated dienes leading to amino sugars; Unusually high “chelation-controlled” diastereoselectivity in the addition to an α,β-dihydroxy imine protected as a ketal.

Midland, M. Mark; McLoughlin, Jim I.

doi:10.1016/s0040-4039(00)80572-9

Cited by 51 publications

(22 citation statements)

References 30 publications

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“…[76] It was later reported by Ojima et al that TiCl 4 is an efficient catalyst for the reaction, [77] and more recently, Kobayashi et al described the use of only 10 mol % of lanthanide triflates as catalysts for an imino-DA reaction. [78] One of the first examples of an asymmetric cycloaddition of an unactivated imine was reported by Midland et al in 1988. [79] The cyclohexylidene-protected a,b-dialkoxy imine 68, which is prepared from l-threonine, reacts with Brassard diene 3 e in the presence of a strong Lewis acid, such as Et 2 AlCl, to afford a single isomer of lactam 69 in high yield [Eq.…”

Section: Reactions Of Chiral Imines Derived From Chiral Carbonyl Compmentioning

confidence: 99%

“…[78] One of the first examples of an asymmetric cycloaddition of an unactivated imine was reported by Midland et al in 1988. [79] The cyclohexylidene-protected a,b-dialkoxy imine 68, which is prepared from l-threonine, reacts with Brassard diene 3 e in the presence of a strong Lewis acid, such as Et 2 AlCl, to afford a single isomer of lactam 69 in high yield [Eq. (31)].…”

Section: Reactions Of Chiral Imines Derived From Chiral Carbonyl Compmentioning

confidence: 99%

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Catalytic Asymmetric Hetero-Diels–Alder Reactions of Carbonyl Compounds and Imines

Jørgensen

2000

Angew. Chem. Int. Ed.

633

145

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Asymmetric catalysis is a challenge for chemists: How can we design catalysts to achieve the goal of forming optically active compounds? This review provides the reader with an overview of the development of catalytic asymmetric hetero‐Diels–Alder reactions of carbonyl compounds and imines. Since its discovery, the Diels–Alder reaction has undergone intensive development and is of fundamental importance for synthetic, physical, and theoretical chemists. The Diels–Alder reaction has been through different stages of development, and at the beginning of the 21st century catalytic Diels–Alder reactions are one of the main areas of focus. The preparation of numerous compounds of importance for our society is based on cycloaddition reactions to carbonyl compounds and imines. There are several parallels between the reactions of carbonyl compounds and those of imines, which, however, begin to vanish on entering the field of catalytic reactions. Why? From a mechanistic point of view some similarities can be drawn, but the synthetic development of catalytic enantioselective hetero‐Diels–Alder reactions of imines are several years behind those of the carbonyl compounds. For hetero‐Diels–Alder reactions of carbonyl compounds there a number of different chiral catalysts, and great progress has been achieved in developing enantioselective reactions for unactivated and activated carbonyl compounds. In contrast the development of catalytic enantioselective hetero‐Diels–Alder reactions of imines is in its infancy and only few catalytic reactions have been published. This review will focus on the most important developments, and discuss the synthetic and mechanistic aspects of enantioselective hetero‐Diels–Alder reactions of carbonyl compounds catalyzed by chiral Lewis acids. For the hetero‐Diels–Alder reactions of imines, the diastereoselective reactions of optically substrates catalyzed by Lewis acids will be presented first, followed by the catalytic enantioselective reactions.

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Section: Reactions Of Chiral Imines Derived From Chiral Carbonyl Compmentioning

confidence: 99%

Section: Reactions Of Chiral Imines Derived From Chiral Carbonyl Compmentioning

confidence: 99%

Catalytic Asymmetric Hetero-Diels–Alder Reactions of Carbonyl Compounds and Imines

Jørgensen

2000

Angew. Chem. Int. Ed.

633

145

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“…The use of highly reactive diethylaluminium chloride was found to promote cycloaddition at low temperatures (Scheme 47). [74] Typically, the imine and the diene (1.1 equiv) were dissolved in CH 2 Cl 2 and the mixture cooled at À78 8C, and then the catalyst was added slowly. The homogeneous solution was allowed to warm to RT and to stand for 2-6 h. After acid-catalysed hydrolysis, the lactams 150 were isolated in fair to good yields.…”

Section: Lewis Acid Mediated Ada Cycloadditionsmentioning

confidence: 99%

Iminium Ions as Dienophiles in Aza‐Diels–Alder Reactions: A Closer Look

Memeo

Quadrelli

2012

Chemistry A European J

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This review highlights the state of the art of the use of iminium ions as dienophiles in Aza-Diels-Alder (ADA) cycloadditions. An historical survey spanning the very first discovery of the reaction to modern developments, mechanistic studies and synthetic applications of the iminium variant of the ADA (iADA) reaction are presented. The discussion is focused on the intermolecular and intramolecular versions of the iADA reactions that are conducted in aqueous solutions to generate, in situ, the reactive dienophile from an amine hydrochloride and either aliphatic or aromatic aldehydes in the presence of a variety of dienes. The retro-ADA reaction is also presented as an interesting method for the protection of amines. The use of Lewis acid catalysis in these reactions was thoroughly studied by the reactions of different amines and aldehydes conducted in the presence of lanthanide(III) complexes.

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“…[76] Später berichteten Ojima et al, dass TiCl 4 ein wirksamer Katalysator für diese Reaktion ist, [77] und Kobayashi et al beschrieben die Verwendung von nur 10 Mol-% eines Lanthanoidtriflats als Katalysator für eine Imino-DA-Reaktion. [78] Eines der ersten Beispiele für die asymmetrische Cycloaddition eines nichtaktivierten Imins beschrieben 1988 Midland et al [79] Das aus l-Threonin hergestellte, Cyclohexylidengeschützte a,b-Dialkoxyimin 68 reagiert mit dem BrassardDien 3 e in Gegenwart einer starken Lewis-Säure wie Et 2 AlCl in hoher Ausbeute zu nur einem Isomer des Lactams 69 [Gl. (31)].…”

Section: Reaktionen Von Chiralen Aus Carbonylverbindungen Erhaltenenunclassified

Katalytische asymmetrische Hetero-Diels-Alder-Reaktionen von Carbonylverbindungen und Iminen

Jørgensen

2000

Angewandte Chemie

160

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besonders der durch chirale Lewis-Säure-Komplexe katalysierten Variante noch gesteigert. [3] Dieser Aufsatz konzentriert sich auf die katalytischen asymmetrischen Hetero-Diels-Alder(HDA)-Reaktionen von Carbonylverbindungen und Iminen mit konjugierten Dienen [Gl. (1)]. AUFS¾TZEHetero-Diels-Alder-Reaktionen aktive HDA-Addukte entstehen. Abschlieûend werden katalytische enantioselektive Reaktionen von Iminen beschrieben. Die HDA-Reaktionen optisch aktiver Imine und Diene wurden in diesen Aufsatz aufgenommen, weil die Verwendung dieser Substrate seit kurzem eingehend untersucht wird, während sich die Entwicklung katalytischer enantioselektiver Reaktionen noch in der Anfangsphase befindet. Mechanistische Aspekte und Konzepte der Aktivierung durch Lewis-SäurenUm HDA-Reaktionen im hier vorliegenden Zusammenhang diskutieren zu können, muss man versuchen, den Reaktionsverlauf aus mechanistischer Sicht zu verstehen. Auf der Basis der relativen Energien der Grenzorbitale (frontier molecular orbitals, FMOs) von Dien und Dienophil lässt sich die Mehrzahl der besprochenen Reaktionen in zwei Arten von [ p 2 s p 4 s ]-Cycloadditionen einordnen: in HDAReaktionen mit normalem und solche mit inversem Elektronenbedarf (Abbildung 1). [2,4] Abbildung 1. FMO-Diagramm für HDA-Reaktionen mit normalem (links; HOMO Dien -LUMO Dienophil -kontrolliert) und inversem Elektronenbedarf (rechts; LUMO Dien -HOMO Dienophil -kontrolliert) mit und ohne Lewis-Säure-Katalyse. X O, NR; LA Lewis-Säure; EDG elektronenschiebende Gruppe.

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A rapid and efficient cycloaddition of simple imines with activated dienes leading to amino sugars; Unusually high “chelation-controlled” diastereoselectivity in the addition to an α,β-dihydroxy imine protected as a ketal.

Cited by 51 publications

References 30 publications

Catalytic Asymmetric Hetero-Diels–Alder Reactions of Carbonyl Compounds and Imines

Catalytic Asymmetric Hetero-Diels–Alder Reactions of Carbonyl Compounds and Imines

Iminium Ions as Dienophiles in Aza‐Diels–Alder Reactions: A Closer Look

Katalytische asymmetrische Hetero-Diels-Alder-Reaktionen von Carbonylverbindungen und Iminen

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