Short Access to (+)-Lupinine and (+)-Epiquinamide via Double Hydroformylation

Airiau, Etienne; Spangenberg, Thomas; Girard, Nicolas; Breit, Bernhard; Mann, André

doi:10.1021/ol902718q

Cited by 63 publications

(28 citation statements)

References 55 publications

(21 reference statements)

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“…Thus, independent domino Michael-Claisen sequences yield octacycle 44 in a single operation that forms four key bonds in the target and promotes the completion of a particularly elegant synthesis. [145] Diels and Alder's first report of the transformation now known as the Diels-Alder reaction involves independent cycloadditions to the two alkenes of benzoquinone by two molecules of cyclopentadiene. [22,146] Another interesting three component reaction using independent dipolar cycloadditions to benzoquinone (45) was recently disclosed by Waldmann and coworkers (Scheme 24).…”

Section: Independent Reactionsmentioning

confidence: 99%

Multi-Bond Forming Processes in Efficient Synthesis

Green¹,

Sherburn²

2013

Aust. J. Chem.

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An increasing number of synthetic organic chemists are embracing the philosophy of efficiency. Herein we highlight multi-bond forming processes, which form two or more new covalent bonds in a single synthetic operation. Such processes, which have the ability to rapidly increase structural complexity, are preeminent in contemporary synthetic organic chemistry. In this short review we classify, analyse, and contrast contemporary multi-bond forming processes, frame these cutting edge contributions within a historical context, and speculate on likely future developments in the area.

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Section: Independent Reactionsmentioning

confidence: 99%

Multi-Bond Forming Processes in Efficient Synthesis

Green¹,

Sherburn²

2013

Aust. J. Chem.

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“…Via deprotonation of the cyclic nitrones and reaction of the corresponding anions with aldehydes the compounds 44 – 54 were obtained (Scheme ). The aldehyde required for the preparation of 46 , but‐3‐enal was prepared according to a literature procedure . Typically, the aldol‐type reaction led to the formation of two diastereomers.…”

Section: Resultsmentioning

confidence: 99%

Total Synthesis of the Natural Herbicide MBH‐001 and Analogues

et al. 2020

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The first total synthesis of the natural herbicide MBH-001 (1) is reported. Structurally it is a 2-methyloxazol-5(2H)-one with a (1-hydroxyethyl) substituent at the 2-position. By relying on cyclic nitrones, a flexible route to MBH-001 and relevant analogues was developed. Key steps include the reaction of a 2-hydroxyimino ester with an aldehyde to form a 5-oxo-2,5dihydrooxazole 3-oxide. In an aldol-type reaction, the anion of these cyclic nitrones reacted with an aldehyde at the 2-position.[a] Scheme 1. Retrosynthetic considerations for MBH-001 (1) and the issue of regioselectivity in reactions of oxazolones with electrophiles. Results and DiscussionInitial studies were performed on oxazolone 4b, obtained by the Steglich method from acylated amino acid [6] 10 using water soluble carbodiimide [7] 11 (Scheme 2). Reaction of aromatic aldehydes 12a-c with oxazolone 4b (isomer of 4a) in the presence of triethylamine or diisopropylethylamine (Hünig′s base) provided the desired addition products with the carbinol connected to C2 (Scheme 2). However, preliminary tests showed that these aryl analogues 13a-13c of MBH-001 have no significant herbicidal activity.Unfortunately, the reaction of oxazolone 4b with acetaldehyde under identical conditions took a different course (Scheme 3). Thus, it seems hydroxyalkylation takes places at C4 to form intermediate A. This intermediate could not be isolated since it reacted with another acetaldehyde molecule to intermediate B followed by opening of the oxazolone ring and formation of 1,3-dioxanone 14, whose structure was confirmed by a single-crystal X-ray diffraction. We cannot rule out that other stereoisomers are formed in this transformation. The aldol-like reaction between 4b and acetaldehyde might be diastereo-Eur.

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“…It is worth mentioning that azidation can proceed in the presence of a multitude of functional groups, including acetals, dithianes, silyloxy ethers, epoxides, amides, amines, and olefins, many of which are reactive under traditional azidation conditions. [8][9][10][11][12][13][14][15][16][20][21][22] Of primary importance for our purposes, tertiary, secondary, primary, and even benzylic alcohols were tolerated (e.g., 2 n-p). At room temperature, reaction times between 30 min and 3 h were typically required to fully convert the starting substrates 1 into the azide-containing products 2.…”

Section: Scope and Limitations Of The Direct Azidationmentioning

confidence: 99%

“…Several common methods for the construction of alkyl azides [8] are based on classical nucleophilic substitution reactions (such as the Mitsunobu reaction with alcohols [9] or substitution with alkyl halides). [10] Unlike the click reaction itself, however, when these methods are applied to multiply functionalized molecules, often, protecting group strategies or lengthy synthetic sequences are necessary due to chemoand regioselectivity issues during the azidation (or the prerequisite halogenation to access alkyl halides).…”

Section: Introductionmentioning

confidence: 99%

Practical Azidation of 1,3‐Dicarbonyls

Harschneck

Hummel

Kirsch

et al. 2011

Chemistry A European J

107

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An operationally simple, direct azidation of 1,3-dicarbonyl compounds has been developed. The reaction proceeds readily under ambient conditions using sodium azide and an iodine-based oxidant such as I(2) or 2-iodoxybenzoic acid (IBX)-SO(3)K/NaI. In particular, the latter method, as a new and well-balanced oxidizing agent, shows excellent functional group tolerance and substrate scope and thus allows access to a variety of tertiary 2-azido and 2,2-bisazido 1,3-dicarbonyl compounds that would be more difficult to access by using traditional methods. Because the azide-containing products easily undergo 1,3-dipolar cycloaddition with alkynes, our report represents a novel route to analogues of sensitive complex molecules.

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Short Access to (+)-Lupinine and (+)-Epiquinamide via Double Hydroformylation

Abstract: Short and efficient access to (+)-lupinine and (+)-epiquinamide by means of an unprecedented double hydroformylation of a bis-homoallylic azide followed by a tandem catalytic hydrogenation/reductive bis-amination is reported.

Cited by 63 publications

References 55 publications

Multi-Bond Forming Processes in Efficient Synthesis

Multi-Bond Forming Processes in Efficient Synthesis

Total Synthesis of the Natural Herbicide MBH‐001 and Analogues

Practical Azidation of 1,3‐Dicarbonyls

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