Organocatalytic Michael addition of aldehydes to a β-silylmethylene malonate to form intermediates for the enantioselective synthesis of hydroxylated valerolactones and piperidines

Chowdhury, Raghunath; Ghosh, Sunil K.

doi:10.1016/j.tetasy.2010.10.011

Cited by 21 publications

(20 citation statements)

References 59 publications

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“…Toward installing the ethylidine unit, they implemented an organocatalyzed enantioselective Michael addition of 29 using a proline-derived catalyst, a reaction based of precedent. [38] Although both 29 and 28 were both more complex than substrates reported in the literature, the desired coupling proceeded smoothly to deliver the selenide 30 in 75 % yield as a 5:1 diastereomeric mixture. The selenide 30 was then converted into the oxidative intramolecular coupling substrate 31 over a five-step sequence.…”

Section: Ma's Oxidative Coupling Approachmentioning

confidence: 91%

Cascade Reactions: A Driving Force in Akuammiline Alkaloid Total Synthesis

et al. 2014

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The akuammiline alkaloids are a family of intricate natural products which have received considerable attention from scientists worldwide. Despite the fact that many members of this alkaloid class were discovered over 50 years ago, synthetic chemistry has been unable to address their architectures until recently. This minireview provides a brief overview of the rich history of the akuammiline alkaloids, including their isolation, structural features, biological activity, and proposed biosyntheses. Furthermore, several recently completed total syntheses are discussed in detail. These examples not only serve to highlight modern achievements in alkaloid total synthesis, but also demonstrate how the molecular scaffolds of the akuammilines have provided inspiration for the discovery and implementation of innovative cascade reactions for the rapid assembly of complex structures.

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Section: Ma's Oxidative Coupling Approachmentioning

confidence: 91%

Cascade Reactions: A Driving Force in Akuammiline Alkaloid Total Synthesis

et al. 2014

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“…A comparison between conventional stirring and ball-milling in the reactions that were catalyzed by (S)-proline (C9) and trans-4-hydroxy-(S)-proline (C10) was also in favor of ball milling (Table 3, entries [11][12][13][14].…”

Section: Solvent-free Conditionsmentioning

confidence: 99%

“…In a prototypical example, the reaction with cyclohexanone gave the product in 92 % yield, syn/anti 99:1, and 97 % ee. Similarly, the addition of aldehydes to nitrodienes [7] and nitroacrylates, [8] the addition of C-nucleophiles to a,b-unsaturated aldehydes, [9] the addition of aldehydes to vinyl sulfones [10] or a,b-silylmethylene malonate, [11] and other organocatalytic Michael additions proceeded well in water, on water, or in brine. [12] Ball-milling, a technique that is well-established in industry, has only recently been introduced in academia for promoting chemical reactions.…”

Section: Introductionmentioning

confidence: 99%

Organocatalyst Efficiency in the Michael Additions of Aldehydes to Nitroalkenes in Water and in a Ball‐Mill

et al. 2012

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The enantioselective organocatalytic Michael addition in aqueous solution was compared with the reaction performed under solvent‐free ball‐milling conditions. A range of pyrrolidine‐derived organocatalysts were tested in the addition of aldehydes to nitroalkenes. Both procedures afforded good yields, diastereoselectivities, and enantioselectivities. The best catalyst in aqueous media was O‐lauroyl‐trans‐4‐hydroxyproline, whilst the ball‐milling technique was most‐efficient with α,α‐diphenyl‐2‐pyrrolidinemethanol trimethylsilyl ether.

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“…In the realm of chiral organosilanes synthesis under organocatalytic conditions, Jørgensen and co‐workers demonstrated an organocatalyzed Michael addition reaction of β‐keto esters with silicon‐substituted α,β‐unsaturated aldehydes followed by acid‐catalysed decarboxylation and aldol condensation for the synthesis of 5‐(trialkylsilyl)cyclohex‐2‐enones (Scheme A) . Ghosh and co‐workers developed asymmetric organocatalyzed direct conjugate addition of alkyl methyl ketones and aldehydes to a β‐silylmethylene malonate to form β‐silyl carbonyl compounds (Scheme B) . In 2011, Hoveyda and co‐workers reported a NHC catalysed silyl conjugate addition to α,β‐unsaturated carbonyl compounds for the synthesis of β‐silyl carbonyl compounds (Scheme C) .…”

Section: Introductionmentioning

confidence: 99%

Organocatalyzed Diastereo‐ and Enantioselective Conjugate Addition of Nitroalkanes to β‐Silylmethylene Malonates: Direct Access to Enantioenriched Organosilanes

2020

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Cinchona-alkaloid derived bifunctional thiourea catalyzed conjugate addition reaction of nitroalkanes to -silylmethylene malonates is reported for direct access of densely functionalized enantioenriched organosilanes in good yields (up to 86 %) with excellent stereoselectivities (up to 98:2 dr and 90 % ee). Using pseudoenantiomeric catalyst, both the enantiomers of the conjugate addition products were easily accessible. Preparative scale synthesis of two conjugate addition products [a] Dr. Scheme 1. Selected state-of-the-art strategies for the synthesis of chiral organosilanes under organocatalytic conditions and present work.nitromethane to aryl/alkylidene malonates took place with moderate yields and long reaction time (3-5 days) in presence of 10 mol-% catalyst and nitromethane as a solvent. In addition, bifunctional iminophosphorane catalysed Michael addition of nitroalkanes to enone diesters is also reported. [19] However, to the best of our knowledge, organocatalytic asymmetric conjugate addition reaction of nitroalkanes to -silylmethylene malonates has not been studied so far. In this paper, we disclose the first catalytic conjugate addition of nitroalkanes including nitromethane to -silylmethylene malonates for the diastereoand enantioselective synthesis of chiral organosilanes (Scheme 1 E). The important feature of these conjugate addition products is the presence of different functional groups which could be useful for downstream synthetic transformation. Results and DiscussionInitially, we started the optimization studies by screening readily available bifunctional hydrogen-bonding organocatalysts [20] I-XII (Figure 2) for the Michael addition reaction betweensilylmethylene malonate1a and nitromethane 2a in toluene as a solvent. To our delight, quinidine derived thiourea catalyst I Eur. 2964 and good enantioselectivities (80-90 % ee) ( Table 2). Thesilylmethylene malonate 1e with the bulky tert-butyldiphenylsilyl group also participated in the conjugate addition reaction in presence of 20 mol-% of catalyst VI at room temperature and

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Organocatalytic Michael addition of aldehydes to a β-silylmethylene malonate to form intermediates for the enantioselective synthesis of hydroxylated valerolactones and piperidines

Cited by 21 publications

References 59 publications

Cascade Reactions: A Driving Force in Akuammiline Alkaloid Total Synthesis

Cascade Reactions: A Driving Force in Akuammiline Alkaloid Total Synthesis

Organocatalyst Efficiency in the Michael Additions of Aldehydes to Nitroalkenes in Water and in a Ball‐Mill

Organocatalyzed Diastereo‐ and Enantioselective Conjugate Addition of Nitroalkanes to β‐Silylmethylene Malonates: Direct Access to Enantioenriched Organosilanes

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