Biomimetic synthesis of yeuhchukene

Cheng, Ke; Kong, Yao; Chan, Tin-Yau

doi:10.1039/c39850000048

Cited by 65 publications

(13 citation statements)

References 2 publications

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“…Such compounds, 3,3 -BIMs, 2,2 -BIMs and 2,3 -BIMs, are present in terrestrial and marine natural products [2][3][4][5]. Many of them, especially 2,3 -BIMs, show extensive biological and pharmaceutical activities [1,[6][7][8][9]. It is very important to build reliable and fast analysis for this class of compounds.…”

Section: Introductionmentioning

confidence: 99%

Radical ions and dehydro cations in detection of 2,3′-bisindolylmethanes using electrospray mass spectrometry

Cai

et al. 2016

International Journal of Mass Spectrometry

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Section: Introductionmentioning

confidence: 99%

Radical ions and dehydro cations in detection of 2,3′-bisindolylmethanes using electrospray mass spectrometry

Cai

et al. 2016

International Journal of Mass Spectrometry

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“…[3] For example, 2-aminocyclopenta[b]indoles, [4a] cyclopenta [b]indole-substituted acetic acids, [4b] and a series of yuehchukene analogues [5] have been successfully synthesized and used in medicinal chemistry. Although a number of methods have been developed for the synthesis of cyclopenta [b]indoles, [6] only few of them are asymmetric and especially catalytic asymmetric methods.…”

mentioning

confidence: 99%

“…In addition, product 7 a represented a potentially useful bisindole subunit, which exists in many natural and pharmaceutical compounds, such as the natural product yuehchukene. [5] The reaction between 5 a (see Table 1, entry 2) and 6 a was promoted by p-TsOH in CHCl 3 and proceeded smoothly to give the desired product 7 a in high yield (95 %) and excellent diastereoselectivity (> 99:1), however, the enantioselectivity of 7 a decreased greatly (83 % ee versus 67 % ee). We then optimized the reaction conditions by screening different Brønsted acid catalysts (see the Supporting Information).…”

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confidence: 99%

“…The substrate scope of N-Bn-protected indoles and aldehydes were investigated next (Table 4). N-Bn-protected indoles bearing electron-withdrawing or electron-donating groups were all suitable reaction partners and gave the corresponding cyclopenta [b]indoles 9 in good yields, and with excellent enantioselectivities and diastereoselectivities (Table 4, entries [1][2][3][4][5]. Cyclopenta [b]indoles with much greater structural complexities could be obtained by changing the aldehyde component.…”

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confidence: 99%

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Multistep One‐Pot Synthesis of Enantioenriched Polysubstituted Cyclopenta[b]indoles

et al. 2011

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The development of asymmetric methodologies for the synthesis of chiral indoles has been a long-standing project in organic synthesis. Indole skeletons are heterocyclic systems and are present in numerous alkaloid products, pharmaceuticals, and agrochemicals.[1] Cyclopenta [b]indole skeletons can be found in a number of indole alkaloids, [2] but have not been extensively reported. Compounds that contain such a unit exhibit a wide range of biological activities.[3] For example, 2-aminocyclopenta[b]indoles, [4a] cyclopenta [b]indole-substituted acetic acids, [4b] and a series of yuehchukene analogues [5] have been successfully synthesized and used in medicinal chemistry. Although a number of methods have been developed for the synthesis of cyclopenta [b]indoles, [6] only few of them are asymmetric and especially catalytic asymmetric methods. [7] To the best of our knowledge, there is only one example of the synthesis of chiral cyclopenta [b]indoles by asymmetric catalysis with acceptable enantioselectivities.[8]The development of efficient methods for the construction of cyclopenta [b]indole units is therefore highly desirable. As a continuation of the work of our research group toward the catalytic asymmetric a-alkylation of carbonyl compounds, [9] we rationally designed a one-pot [10] three-step reaction, which consisted of the a-alkylation of an aldehyde, catalyzed by a primary-amine-substituted thiourea, [11] and two consecutive Brønsted acid catalyzed Friedel-Crafts reactions of an indole, [12] to construct chiral polysubstituted cyclopenta [b]indoles (Scheme 1). Herein, we report these consecutive organocatalyzed reactions, which gave structurally diverse cyclopenta [b]indoles in high yields (up to 85 %), and with excellent diastereoselectivities (up to > 99:1) and enantioselectivities (up to 99 % ee).The reactions shown in Scheme 1 were realized in three stages. In the first stage, we examined the a-alkylation of isobutylaldehyde 4 a with 3-indolylmethanol 3 a (step 1) under catalysis by chiral amines 1 and acids 2. Although several methods for the asymmetric amine-based catalysis have been used in similar a-alkylation reactions of aldehydes with diarylmethanol compounds, [11] to date a,a-disubstituted aldehydes have not been used as donors. For the method reported herein, a,a-disubstituted aldehydes were very important precursors because they could produce aldehydes 5 (Scheme 1), which could not be enolated during the following Friedel-Crafts alkylations; thus, there were fewer side reactions in this method. Several amine-based catalysts were investigated in the a-alkylation reaction of aldehyde 4 a.

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“…Compounds that contain such a unit exhibit a wide range of biological activities. [3] For example, 2-aminocyclopenta [b]indoles, [4a] cyclopenta [b]indole-substituted acetic acids, [4b] and a series of yuehchukene analogues [5] have been successfully synthesized and used in medicinal chemistry. Although a number of methods have been developed for the synthesis of cyclopenta [b]indoles, [6] only few of them are asymmetric and especially catalytic asymmetric methods.…”

mentioning

confidence: 99%

Multistep One‐Pot Synthesis of Enantioenriched Polysubstituted Cyclopenta[b]indoles

Guo

Jin

et al. 2011

Angewandte Chemie

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The development of asymmetric methodologies for the synthesis of chiral indoles has been a long-standing project in organic synthesis. Indole skeletons are heterocyclic systems and are present in numerous alkaloid products, pharmaceuticals, and agrochemicals. [1] Cyclopenta [b]indole skeletons can be found in a number of indole alkaloids, [2] but have not been extensively reported. Compounds that contain such a unit exhibit a wide range of biological activities. [3] For example, 2-aminocyclopenta[b]indoles, [4a] cyclopenta [b]indole-substituted acetic acids, [4b] and a series of yuehchukene analogues [5] have been successfully synthesized and used in medicinal chemistry. Although a number of methods have been developed for the synthesis of cyclopenta[b]indoles, [6] only few of them are asymmetric and especially catalytic asymmetric methods. [7] To the best of our knowledge, there is only one example of the synthesis of chiral cyclopenta[b]indoles by asymmetric catalysis with acceptable enantioselectivities. [8] The development of efficient methods for the construction of cyclopenta[b]indole units is therefore highly desirable. As a continuation of the work of our research group toward the catalytic asymmetric a-alkylation of carbonyl compounds, [9] we rationally designed a one-pot [10] three-step reaction, which consisted of the a-alkylation of an aldehyde, catalyzed by a primary-amine-substituted thiourea, [11] and two consecutive Brønsted acid catalyzed Friedel-Crafts reactions of an indole, [12] to construct chiral polysubstituted cyclopenta [b]indoles (Scheme 1). Herein, we report these consecutive organocatalyzed reactions, which gave structurally diverse cyclopenta [b]indoles in high yields (up to 85 %), and with excellent diastereoselectivities (up to > 99:1) and enantioselectivities (up to 99 % ee).The reactions shown in Scheme 1 were realized in three stages. In the first stage, we examined the a-alkylation of isobutylaldehyde 4 a with 3-indolylmethanol 3 a (step 1) under catalysis by chiral amines 1 and acids 2. Although several methods for the asymmetric amine-based catalysis have been used in similar a-alkylation reactions of aldehydes with diarylmethanol compounds, [11] to date a,a-disubstituted aldehydes have not been used as donors. For the method reported herein, a,a-disubstituted aldehydes were very important precursors because they could produce aldehydes 5 (Scheme 1), which could not be enolated during the following Friedel-Crafts alkylations; thus, there were fewer side reactions in this method. Several amine-based catalysts were investigated in the a-alkylation reaction of aldehyde 4 a.

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Biomimetic synthesis of yeuhchukene

Cited by 65 publications

References 2 publications

Radical ions and dehydro cations in detection of 2,3′-bisindolylmethanes using electrospray mass spectrometry

Radical ions and dehydro cations in detection of 2,3′-bisindolylmethanes using electrospray mass spectrometry

Multistep One‐Pot Synthesis of Enantioenriched Polysubstituted Cyclopenta[b]indoles

Multistep One‐Pot Synthesis of Enantioenriched Polysubstituted Cyclopenta[b]indoles

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