Chemie freier cyclischer vicinaler Tricarbonyl‐Verbindungen (‘1,2,3‐Trione’). Teil 3

Schank, Kurt; Lieder, Robert; Lick, Carlo; Glock, Rebecca

doi:10.1002/hlca.200490085

Cited by 19 publications

(8 citation statements)

References 122 publications

(26 reference statements)

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“…It has been reported that vic-triketones react with enamines. 45 For the present case, it was found that monohydrate 104 reacts with enamine 105 without addition of dehydrating agents. Aldol 106 was formed stereoselectively, with the enamine approaching the central carbonyl group of the in-situ formed vic-triketone from the face opposite to the TBDPS ether.…”

Section: Short Review Syn Thesismentioning

confidence: 51%

“…25 The 2,3,7-triketo ester 41 used for cyclisation was prepared from enol diazoacetate 40 via Mukaiyama-Michael reaction followed by oxidation with DMDO and dehydration under reduced pressure (Scheme 8). According to whether a Brønsted or Lewis acid was used in the subsequent cyclisation step, the syn- (44) or anti-product (45) was obtained selectively. As suggested by the authors, this diastereoselectivity arises from different ways of carbonyl activation.…”

Section: Short Review Syn Thesismentioning

confidence: 99%

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Vicinal Tricarbonyl Compounds: Versatile Building Blocks for Natural Product Synthesis

et al. 2016

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Due to their high density of functional groups, vicinal tricarbonyl compounds are versatile building blocks for the synthesis of complex target molecules. Methods for their preparation and their use in stereoselective CC bond formations, as well as for the synthesis of heteroaromatics, are summarised for the period 2006-2016. Several examples for their applications in natural product synthesis (awajanomycin, cladoniamide, wailupemycin) are presented. 1 Introduction 2 Preparation of Vicinal Tricarbonyl Compounds 3 Use in Stereoselective CC Bond Formations 4 Use for the Synthesis of Heteroaromatics 5 Examples from Natural Product Synthesis 6 Conclusion Key words vicinal tricarbonyl compounds, stereoselective synthesis, natural products, total synthesis, regioselectivity Lars Selter (from left to right) was born in Berlin, Germany in 1989. He studied chemistry at the Freie Universität Berlin and received his B.Sc. degree in 2011 and his M.Sc. degree in 2013 under the supervision of Prof. H.-U. Reißig. Currently, he is working as a Ph.D. student at the Philipps-Universität Marburg under the guidance of Prof. U. Koert focusing on regioselective CC bond formation on vicinal tricarbonyl compounds. Lukas Zygalski was born in Rotenburg/Fulda, Germany in 1990. He completed his B.Sc. degree in 2013 and his M.Sc. degree (specialisation in organic chemistry) in 2016 under the supervision of Prof. U. Koert at the Philipps-Universität Marburg. Currently, he is working there as a Ph.D. student focusing on natural product synthesis. Eric Kerste was born in Rotenburg/Fulda, Germany in 1990. He completed his B.Sc. degree in 2013 and his M.Sc. degree (specialisation in organic chemistry) in 2016, both under the supervision of Prof. U. Koert at the Philipps-Universität Marburg. Currently, he is working there as a Ph.D. student focusing on natural product synthesis based on vicinal diketo esters. Ulrich Koert was born in Hanau, Germany in 1961. He studied chemistry at the Goethe Universität in Frankfurt where he obtained his Ph.D. in

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Section: Short Review Syn Thesismentioning

confidence: 51%

Section: Short Review Syn Thesismentioning

confidence: 99%

Vicinal Tricarbonyl Compounds: Versatile Building Blocks for Natural Product Synthesis

et al. 2016

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“…Schank et al have shown that free cyclic vicinal triketones react with enamines. 15 For the present case, it was found, that the monohydrate 9 reacts with the morpholine enamine 14 16 without any additive at room temperature to produce the desired aldol 13.…”

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confidence: 64%

Vic-Tricarbonyl Compounds: Synthesis of (±)-9-epi-Wailupemycin A

Seitz¹,

Harms²,

Koert³

2013

Synthesis

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A synthesis of the 9-epimer of the marine natural product wailupemycin A is reported. The key reaction sequence consists of a diastereoselective enamine addition to a tricarbonyl monohydrate, the formation of an enol silyl acetal, and finally the stereocontrolled addition of the α-pyrone substructure.The use of vic-tricarbonyl compounds as polyelectrophiles in organic synthesis is mainly restricted to their reaction with O-and N-nucleophiles. 1,2 The stereocontrolled addition of C-nucleophiles has been studied with diethyl ketomalonate. 3 The crotylboration of vic-diketo amides and vic-diketo esters was possible with high diastereoselectivity and complementary regioselectivity. 4 A diastereoselective intramolecular aldol reaction of a vicdiketo ester has been achieved. 5 The asymmetric crotylboration of a vic-tricarbonyl compound was used as a key step in the total synthesis of awajanomycin. 6 Wailupemycin A (1) and wailupemycin B (2) (Figure 1) are α-pyrone containing metabolites from the marine derived actinomycete BD-26T(20) isolated from sediments, which were collected at Wailupe beach south east of Hawai. 7 The structures of both compounds were determined by combined spectroscopic techniques. The wailupemycins were tested for antimicrobial activity against Bacillus subtilis, Staphylococcus areus, and Escherica coli. While wailupemycin B (2) was inactive, wailupemycin A (1) showed activity against E. coli. 7 The biosynthesis of the wailupemycins has been investigated and analogues have been prepared via mutasynthesis. 8 A total synthesis of enantiomerically pure wailupemycin B (2) has been reported by Bach and Kirsch. 9 Here, we present a synthesis of (±)-9-epi-wailupemycin A that focuses on the use of a vic-tricarbonyl compound as the key intermediate. The retrosynthetic consideration of the wailupemycin A structure 3 leads to the vic-triketone 4, acetophenone 5, and the methyl-α-pyrone 6 (Scheme 1). A successive addition of enolates or enolate equivalents of 5 and 6 to the tricarbonyl substructure 4 could be used to assemble the target structure.For initial studies, cyclohexane-1,2,3-trione (10) was chosen as test substrate for the addition of 5 and 6 (Scheme 2). Figure 1 Structures of wailupemycin A (1) and wailupemycin B (2)

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“…Although we could not identify the oxidation agent required in this reaction, the most plausible one is considered to be ninhydrin, based on the result that 4 was obtained even when the reaction was carried out under nitrogen. Ninhydrin itself could participate in oxidation [13], because the C2 position of ninhydrin has “umpolung” ability. The carbocation at C2, resulting from the release of the OH group as an anion, should be stabilized by accepting electrons to be converted to a carbanion.…”

Section: Resultsmentioning

confidence: 99%

Novel Rearrangements in the Reactions Directed Toward Preparation of Spiro-N,N-ketals: Reactions of Naphthalene-1,8-diamine with Ninhydrin and Isatin

et al. 2012

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Spiro-N,N-ketal 5, consisting of a phthaloperine heterocyclic ring and a naphtha[1,8-ef][1,4]diazepine ring, was obtained along with spiro-N,N-ketal 2 via 2,2-condensation in the reaction of ninhydrin with naphthalene-1,8-diamine. Their molecular structures were elucidated by X-ray crystal structural analysis. Aside from these spiro compounds, the diazapleiadiene compound 3 formed by 1,2-condensation and the 1,4-isoquinolinedione compound 4 arising from ring expansion were isolated. When isatin was reacted with naphthalene-1,8-diamine, spiro-N,N-ketal 6 and the two 1H-perimidine-based compounds 7 and 8 were isolated. Compound 8 was revealed to undergo a fast dynamic prototropic tautomerization in solution. Plausible mechanisms of the formation of the products are proposed.

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Chemie freier cyclischer vicinaler Tricarbonyl‐Verbindungen (‘1,2,3‐Trione’). Teil 3

Cited by 19 publications

References 122 publications

Vicinal Tricarbonyl Compounds: Versatile Building Blocks for Natural Product Synthesis

Vicinal Tricarbonyl Compounds: Versatile Building Blocks for Natural Product Synthesis

Vic-Tricarbonyl Compounds: Synthesis of (±)-9-epi-Wailupemycin A

Novel Rearrangements in the Reactions Directed Toward Preparation of Spiro-N,N-ketals: Reactions of Naphthalene-1,8-diamine with Ninhydrin and Isatin

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