- A convenient synthesis of chiral oxazolidin-2-ones and thiazolidin-2-ones and an improved preparation of triphosgene
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Oxazolidin-2-ones and thiazolidin-2-ones are conveniently prepared by condensation of L-serine, L-threonine and L-cysteine, respectively with triphosgene. The corresponding methyl esters may be subsequently obtained by quenching the reaction mixture with methanol, without prior need for the isolation of the free acids. An improved procedure for preparation of triphosgene using an internal cooling system is described.
- Falb,Nudelman,Hassner
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- Metal-Free Selective Modification of Secondary Amides: Application in Late-Stage Diversification of Peptides
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Here we solve a long-standing challenge of the site-selective modification of secondary amides and present a simple two-step, metal-free approach to selectively modify a particular secondary amide in molecules containing multiple primary and secondary amides. Density functional theory (DFT) provides insight into the activation of C-N bonds. This study encompasses distinct chemical advances for late-stage modification of peptides thus harnessing the amides for the incorporation of various functional groups into natural and synthetic molecules.
- Adebomi, Victor,Sriram, Mahesh,Streety, Xavier,Raj, Monika
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supporting information
p. 6189 - 6193
(2021/08/01)
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- Acceptor-Controlled Transfer Dehydration of Amides to Nitriles
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Palladium-catalyzed dehydration of primary amides to nitriles efficiently proceeds under mild, aqueous conditions via the use of dichloroacetonitrile as a water acceptor. A key to the design of this transfer dehydration catalysis is the identification of an efficient water acceptor, dichloroacetonitrile, that preferentially reacts with amides over other polar functional groups with the aid of the Pd catalyst and makes the desired scheme exergonic, thereby driving the dehydration.
- Okabe, Hiroyuki,Naraoka, Asuka,Isogawa, Takahiro,Oishi, Shunsuke,Naka, Hiroshi
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supporting information
p. 4767 - 4770
(2019/06/17)
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- Visible-Light-Mediated Liberation and In Situ Conversion of Fluorophosgene
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The first example for the photocatalytic generation of a highly electrophilic intermediate that is not based on radical reactivity is reported. The single-electron reduction of bench-stable and commercially available 4-(trifluoromethoxy)benzonitrile by an organic photosensitizer leads to its fragmentation into fluorophosgene and benzonitrile. The in situ generated fluorophosgene was used for the preparation of carbonates, carbamates, and urea derivatives in moderate to excellent yields via an intramolecular cyclization reaction. Transient spectroscopic investigations suggest the formation of a catalyst charge-transfer complex-dimer as the catalytic active species. Fluorophosgene as a highly reactive intermediate, was indirectly detected via its next downstream carbonyl fluoride intermediate by NMR. Furthermore, detailed NMR analyses provided a comprehensive reaction mechanism including a water dependent off-cycle equilibrium.
- Petzold, Daniel,Nitschke, Philipp,Brandl, Fabian,Scheidler, Veronica,Dick, Bernhard,Gschwind, Ruth M.,K?nig, Burkhard
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supporting information
p. 361 - 366
(2018/11/23)
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- Carbon dioxide as a carbonylating agent in the synthesis of 2-oxazolidinones, 2-oxazinones, and cyclic ureas: Scope and limitations
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Carbon dioxide can be used as a convenient carbonylating agent in the synthesis of 2-oxazolidinones, 2-oxazinones, and cyclic ureas. The transient carbamate anion generated by treating a primary or secondary amine group in basic media can be activated with phosphorylating agents such as Diphenylphosphoryl azide (DPPA) and Diphenyl chlorophosphate (DPPCl) but also with other types of electrophiles such as SOCl2, TsCl, or AcCl. The intramolecular trapping of the activated carbamate by a hydroxyl group leads to the formation of 2-oxazolidinones or 2-oxazinones in good to excellent yields. This methodology was successfully applied to the synthesis of cyclic ureas up to 7-membered rings from the corresponding diamines.
- Paz, Jairo,Perez-Balado, Carlos,Iglesias, Beatriz,Munoz, Luis
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experimental part
p. 3037 - 3046
(2010/07/15)
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- Total Synthesis of (+)-Latrunculin A, an Ichthyotoxic Metabolite of the Sponge Latrunculia magnifica, and Its C-15 Epimer
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Latrunculin A (1), an ichthyotoxic metabolite of the sponge Latrunculia magnifica with potent inhibitory action on microfilament-mediated processes involved in cell division, was synthesized via a convergent approach.Construction of a major segment of the latrunculin backbone was accomplished by means of a three-component coupling of aldehyde 24, β-keto ester 27, and phosphonium salt 26, which established the conjugated E,Z-diene moiety of 31.The thiazolidinone subunit of 1 was elaborated in the form of 39 from L-cysteine and was linked to 35 without nitrogen protection.Final lactonization of 47 was carried out using the Mitsunobu protocol.A parallel sequence employing the epimeric seco acid 48 produced 15-epilatrunculin A.
- White, James D.,Kawasaki, Motoji
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p. 5292 - 5300
(2007/10/02)
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- SYNTHESIS OF BOTH ENANTIOMERS OF 8-AZA-11-DEOXY-10-THIAPROSTAGLANDIN E1
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Synthesis of both enantiomers of 8-aza-11-deoxy-10-thiaprostaglandin E1 has been achieved starting from D- and L-cysteine, respectively.
- Kubodera, Noboru,Nagano, Hiroyuki,Takagi, Michiro,Matsunaga, Isao
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p. 259 - 263
(2007/10/02)
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