- N-triazinylammonium tetrafluoroborates. A new generation of efficient coupling reagents useful for peptide synthesis
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A new generation of triazine-based coupling reagents (TBCRs), designed according to the concept of "superactive esters", was obtained by treatment of 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium (DMTMM) chloride with lithium or silver tetrafluoroborate. The structure of 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium tetrafluoroborate was confirmed by X-ray diffraction. Activation of carboxylic acids by using this reagent proceeds via triazine "superactive ester". The coupling reagent was successfully used for the synthesis of Z-, Boc-, and Fmoc-protected dipeptides derived from natural and unnatural sterically hindered amino acids and for fragment condensation, in 80-100% yield and with high enantiomeric purity. The manual SPPS of the ACP(65-74) peptide fragment (H-Val-Gln-Ala-Ala- lle-Asp-Tyr-Ile-Asn-Gly-OH) proceeded significantly faster than with TBTU or HATU, as well as the automated SPPS of the same fragment gave a purer product than by using TBTU or PyBOP. The reagent was also demonstrated to be efficient in on-resin head-to-tail cyclization of constrained cyclopeptides, in SPPS synthesis of Aib peptides, and in the synthesis of esters from appropriate acids, alcohols, and phenols. The high efficiency and versatility of this new generation of TBCRs confirm, for the first time, the usefulness of the concept of "superactive esters" in rational design of the structure of coupling reagents.
- Kaminski, Zbigniew J.,Kolesinska, Beata,Kolesinska, Justyna,Sabatino, Giuseppina,Chelli, Mario,Rovero, Paolo,Blaszczyk, Michal,Glowka, Marek L.,Papini, Anna Maria
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- A Strategy for Accessing Aldehydes via Palladium-Catalyzed C?O/C?N Bond Cleavage in the Presence of Hydrosilanes
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We report the catalytic reduction of both active esters and amides by selective C(acyl)?X (X=O, N) cleavage to access aldehyde functionality via a palladium-catalyzed strategy. Reactions are promoted by hydrosilanes as reducing reagents with good to excellent yields and with excellent chemoselectivity for C(acyl)?N and C(acyl)?O bond cleavage. Carboxylic acid C(acyl)?O bonds are activated by 2-chloro-4,6-dimethoxy-1,3,5-triazine (CDMT) to form triazine ester intermediates, which further react with hydrosilanes to yield aldehydes in one-pot two-step procedures. We demonstrate that C(acyl)?O cleavage/formylation offers higher yields and broader substrate scopes compared with C(acyl)?N cleavage under the same reaction conditions.
- He, Zhanyu,Liu, Tingting,Ru, Junxiang,Wang, Yulin,Wang, Zijia,Zeng, Zhuo
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supporting information
p. 5794 - 5800
(2020/12/01)
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- One-pot synthesis of cinnamic anhydrides from cinnamic acids and 6-chloro-2,4-dimethoxy-sec-triazine (CDMT) at room temperature
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Symmetric cinnamic anhydrides were prepared by the reactions of cinnamic acid substrates with 6-chloro-2,4-dimethoxy-sec-triazine. The reactions were performed at room temperature for 15 h. Diverse cinnamic acid substrates bearing electron-withdrawing or -donating groups worked well, providing the corresponding cinnamic anhydrides in moderate-to-good yields.
- Raja, Gabriel Charles Edwin,Son, Yujeong,Kim, Myungjin,Lee, Sunwoo,Oh, Jonghoon
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p. 2449 - 2455
(2017/12/12)
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- Development of a method for the synthesis of 2,4,5-trisubstituted oxazoles composed of carboxylic acid, amino acid, and boronic acid
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A novel method for the synthesis of trisubstituted oxazoles via a one-pot oxazole synthesis/Suzuki–Miyaura coupling sequence has been developed. One-pot formation of 5-(triazinyloxy)oxazoles using carboxylic acids, amino acids and a dehydrative condensing reagent, DMT-MM, followed by Ni-catalyzed Suzuki–Miyaura coupling with boronic acids provided the corresponding 2,4,5-trisubstituted oxazoles in good yields.
- Yamada, Kohei,Kamimura, Naoto,Kunishima, Munetaka
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supporting information
p. 1478 - 1485
(2017/08/02)
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- One-Pot Synthesis of Arylketones from Aromatic Acids via Palladium-Catalyzed Suzuki Coupling
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A palladium-catalyzed one-pot procedure for the synthesis of aryl ketones has been developed. Triazine esters when coupled with aryl boronic acids provided aryl ketones in moderate to excellent yields (up to 95%) in the presence of 1 mol % Pd(PPh3)2Cl2 for 30 min. (Chemical Equation Presented).
- Wu, Hongxiang,Xu, Baiping,Li, Yue,Hong, Fengying,Zhu, Dezhao,Jian, Junsheng,Pu, Xiaoer,Zeng, Zhuo
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p. 2987 - 2992
(2016/04/26)
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- Privilege Ynone Synthesis via Palladium-Catalyzed Alkynylation of "Super-Active Esters"
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A neat palladium-catalyzed alkynylation reaction was developed with "super-active ester" as the carbonyl electrophile, which provides a clean and efficient synthetic protocol for a broad array of ynone compounds under CO-, Cu-, ligand-, and base-free conditions. The superior activity of triazine ester was rationalized by the strong electron-withdrawing ability and the unique affinity of triazine on palladium. A mechanistic experiment clearly demonstrated that the N-Pd coordination of triazine plays a crucial role for the highly efficient C-O activation. (Chemical Equation presented).
- Yu, Bo,Sun, Huaming,Xie, Zunyuan,Zhang, Guofang,Xu, Li-Wen,Zhang, Weiqiang,Gao, Ziwei
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supporting information
p. 3298 - 3301
(2015/07/15)
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- A simple and straightforward protocol to 3,5-disubstituted 1,2,4-oxadiazoles from carboxylic acids
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A convenient one-pot synthesis of 1,2,4-oxadiazoles is described. The condensation of carboxylic acids and amidoximes in the presence of 2-chloro-4,6-dimethoxy-1,3,5-triazine (CDMT) and N-methylmorpholine (NM1 B) has been employed to synthesize a variety of 3,5-disubstituted 1,2,4-oxadiazoles in good to excellent yields. The methodology has been applied for the synthesis of a metabotropic glutamate subtype 5 (mGlu5) receptor antagonist.
- Ramu, Tadikonda,Prasanthi, Sarakula,Mangarao, Nakka,Basha, Gajula Mahaboob,Srinuvasarao, Rayavarapu,Siddaiah, Vidavalur
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supporting information
p. 722 - 724
(2013/07/26)
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- One-pot preparation of oxazol-5(4H)-ones from amino acids in aqueous solvents
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A method for one-pot synthesis of oxazol-5(4H)-ones has been developed using 4-(4,6-dimethoxy-l,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMT-MM), which is available for the activation of carboxylic acids in an aqueous solvent. The oxazolones were prepared by the TV-acylation of amino acids with carboxylic acids and the subsequent cyclodehydration of the resulting N-acylamino acids by the addition of N,N-diethylaniline. Since both these reactions proceed effectively with the same coupling reagent, DMT-MM, in aqueous solvents, the procedure is simplified and becomes easy to perform. In addition, 5-(triazinyloxy)oxazole derivatives have been synthesized by controlling the basicity of the reaction system.
- Fujita, Hikaru,Kunishima, Munetaka
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experimental part
p. 907 - 912
(2012/08/08)
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- A fast and efficient one-pot microwave assisted synthesis of variously di-substituted 1,2,4-oxadiazoles
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A one-pot two-step microwave assisted synthesis of variously disubstituted 1,2,4-oxadiazoles from carboxylic acids and amidoximes is reported. This methodology is characterized by short reaction times, is versatile, robust and high-yielding and allows for
- Porcheddu, Andrea,Cadoni, Roberta,De Luca, Lidia
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supporting information; experimental part
p. 7539 - 7546
(2011/12/03)
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- Design, synthesis, and application of enantioselective coupling reagent with a traceless chiral auxiliary
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(Chemical Equation Presented) Stable chiral N-triazinylbrucinium tetrafluoroborate enantioselectively activates racemic carboxylic acids yielding enantiomerically enriched amides, esters, and dipeptides with er from 8:92 to 0.5:99.5. Due to the departure
- Kolesinska, Beata,Kaminski, Zbigniew J.
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supporting information; experimental part
p. 765 - 768
(2009/09/06)
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- Mild and efficient synthesis of carboxylic acid anhydrides from carboxylic acids and triazine coupling reagents
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Anhydrides of carboxylic acids were obtained in 53%-95% yield by treatment of appropriate carboxylic acids with 2-chloro-4,6-dimethoxy-1,3,5-triazine (CDMT) or 2,4-dichloro-6-methoxy-1,3,5-triazine (DCMT) in the presence of N-methylmorpholine. It has been proved that synthesis proceeds via triazine active esters 3a,b, which are able to acylate carboxylate anion but not less nucleophilic carboxylic acid.
- Kaminski, Zbigniew J.,Kolesinska, Beata,Malgorzata, Marcinkowska
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p. 3349 - 3358
(2007/10/03)
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- A Simple Preparation of Ketones. N-Protected α-Amino Ketones from α-Amino Acids
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matrix presented Carboxylic acids and amino acids are readily converted, under mild conditions, into the corresponding activated esters, which are reacted with Grignard/Cul reagent to give the corresponding ketones in nearly quantitative yields. The compounds were recovered substantially pure from the reaction mixtures.
- De Luca, Lidia,Giacomelli, Giampaolo,Porcheddu, Andrea
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p. 1519 - 1521
(2007/10/03)
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