3972-41-6Relevant academic research and scientific papers
Copper-catalyzed cross-coupling of amino acid-derived amides with (Z)-vinyl iodides: Unexpected solvent effect and preparation of plocabulin
Wang, Leiming,Lei, Xinsheng,Wang, Quanrui,Li, Yingxia
, (2021/02/01)
A copper-catalyzed cross-coupling reaction of amino acid-derived amides and (Z)-vinyl iodide was studied to improve a key step in the synthesis of plocabulin, a novel microtubule destabilizer agent of marine origin. The study revealed a profound solvent effect with 1,2-dimethoxyethane (DME), which gave consistently high yields across a large variety of the amide and (Z)-vinyl iodide substrates. The protocol was successfully utilized in the preparation of plocabulin and provided a significantly improved yield.
Stereospecific Nickel-Catalyzed Reductive Cross-Coupling of Alkyl Tosylate and Allyl Alcohol Electrophiles
Alexanian, Erik J.,Tercenio, Quentin D.
supporting information, p. 7215 - 7219 (2021/09/22)
The stereospecific cross-coupling of easily accessed electrophiles holds significant promise in the construction of C-C bonds. Herein, we report a nickel-catalyzed reductive coupling of allyl alcohols with chiral, nonracemic alkyl tosylates. This cross-coupling delivers valuable allylation products with high levels of stereospecificity across a range of substrates. The catalytic system consists of a simple nickel salt in conjunction with a commercially available reductant and importantly represents a rare example of a cross-coupling involving the C-O bonds of two electrophiles.
Stereoselective synthesis of resorcylic acid lactone Cochliomycin B
Nagalatha,Siva Ganesh,Venkat Narsaiah
, (2021/09/22)
The total synthesis of 14-membered resorcylic acid lactone, Cochliomycin B has prescribed, in a convergent manner, from readily available starting materials, D-galactose, L-aspartic acid and ethyl acetoacetate. The key reactions involved in the synthesis are Julia-Kocienski olefination, E-selective Horner-Wadsworth-Emmons olefination and intramolecular lactonization.
Stereoselective total synthesis of obolactones and 7′,8′-dihydroobolactones
Fernandes, Rodney A.,Kumar, Praveen,Saini, Deepak
, p. 18976 - 18982 (2021/10/29)
A concise stereoselective total synthesis of two diastereomeric obolactones and 7′,8′-dihydroobolactones has been achieved using a metal-free catalytic δ-hydroxyalkynone rearrangement, which could provide the required dihydro-γ-pyrone moiety. The desired first stereogenic center was installed through the chiral pool material,l-aspartic acid. Next, the allylation reaction was strategically utilized to provide the requisite olefin bond for the intended ring-closing metathesis, allowing the installation of the remaining dihydro-α-pyrone moiety in the natural products. It also enabled the targeting of both dihydro-α-pyrone diastereomers. Thus, the first stereoselective total synthesis of (+)-7′,8′-dihydroobolactone was accomplished, establishing its structure and absolute configuration.
Stereoselective total synthesis of C2-symmetric natural products pyrenophorol and its derivatives
Narala, Siva Ganesh,Nagalatha,Venkat Narsaiah
supporting information, p. 2173 - 2178 (2019/03/11)
A stereoselective total synthesis of 16-membered C2-symmetric macrodiolide Pyrenophorol, Tetrahydropyrenophorol and 4,4-diacetylpyrenophorol have been accomplished. The synthesis started from commercially available L-Aspartic acid and the key reactions involved are regioselective epoxide opening, CBS reduction, Pinnick oxidation and Mitsunobu dilactonization.
Synthesis and Evaluation of Novel TLR2 Agonists as Potential Adjuvants for Cancer Vaccines
Lu, Benjamin L.,Williams, Geoffrey M.,Verdon, Daniel J.,Dunbar, P. Rod,Brimble, Margaret A.
supporting information, p. 2282 - 2291 (2019/10/02)
Cancer immunotherapy has gained increasing attention due to its potential specificity and lack of adverse side effects when compared to more traditional modes of treatment. Toll-like receptor 2 (TLR2) agonists are lipopeptides possessing the S-[2,3-bis(palmitoyloxy)propyl]-l-cysteine (Pam2Cys) motif and exhibit potent immunostimulatory effects. These agonists offer a means of providing "danger signals" in order to activate the immune system toward tumor antigens. Thus, the development of TLR2 agonists is attractive in the search of potential immunostimulants for cancer. Existing SAR studies of Pam2Cys with TLR2 indicate that the structural requirements for activity are, for the most part, very intolerable. We have investigated the importance of stereochemistry, the effect of N-terminal acylation, and homologation between the two ester functionalities in Pam2Cys-conjugated lipopeptides on TLR2 activity. The R diastereomer is significantly more potent than the S diastereomer and N-terminal modification generally lowers TLR2 activity. Most notably, homologation gives rise to analogues which are comparatively active to the native Pam2Cys containing constructs.
PEPTIDE CONJUGATES, CONJUGATION PROCESS, AND USES THEREOF
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Page/Page column 135, (2019/03/17)
The invention relates to peptide conjugates, methods for making peptide conjugates, conjugates produced by the methods, and pharmaceutical compositions comprising the conjugates. Methods of eliciting immune responses in a subject and methods of vaccinating a subject, uses of the conjugates for the same, and uses of the conjugates in the manufacture of medicaments for the same are also contemplated.
AMINO ACID AND PEPTIDE CONJUGATES AND CONJUGATION PROCESS
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Page/Page column 131; 132, (2017/09/09)
The invention relates to amino acid and peptide conjugates, methods for making amino acid and peptide conjugates, conjugates produced by the methods, and pharmaceutical compositions comprising the conjugates. Methods of eliciting immune responses in a subject and methods of vaccinating a subject, uses of the conjugates for the same, and uses of the conjugates in the manufacture of medicaments for the same are also contemplated.
Identification and pharmacological characterization of succinate receptor agonists
Geubelle, Pierre,Gilissen, Julie,Dilly, Sébastien,Poma, Laurence,Dupuis, Nadine,Laschet, Céline,Abboud, Dayana,Inoue, Asuka,Jouret, Fran?ois,Pirotte, Bernard,Hanson, Julien
supporting information, p. 796 - 808 (2017/04/14)
Background and Purpose: The succinate receptor (formerly GPR91 or SUCNR1) is described as a metabolic sensor that may be involved in homeostasis. Notwithstanding its implication in important (patho)physiological processes, the function of succinate receptors has remained ill-defined because no pharmacological tools were available. We report on the discovery of the first family of potent synthetic agonists. Experimental Approach: We screened a library of succinate analogues and analysed their activity on succinate receptors. Also, we modelled a pharmacophore and a binding site for this receptor. New agonists were identified based on the information provided by these two approaches. Their activity was studied in various bioassays, including measurement of cAMP levels, [Ca2+]i mobilization, TGF-α shedding and recruitment of arrestin 3. The in vivo effects of activating succinate receptors with these new agonists was evaluated on rat BP. Key Results: We identified cis-epoxysuccinic acid and cis-1,2-cyclopropanedicarboxylic acid as agonists with an efficacy similar to that of succinic acid. Interestingly, cis-epoxysuccinic acid was 10- to 20-fold more potent than succinic acid on succinate receptors. For example, cis-epoxysuccinic acid reduced cAMP levels with a pEC50?=?5.57?±?0.02 (EC50?=?2.7?μM), compared with succinate pEC50?=?4.54?±?0.08 (EC50?=?29?μM). The rank order of potency of the three agonists was the same in all in vitro assays. Both cis-epoxysuccinic and cis-1,2-cyclopropanedicarboxylic acid were as potent as succinate in increasing rat BP. Conclusions and Implications: We describe new agonists at succinate receptors that should facilitate further research on this understudied receptor.
Accessing Centnerszwer's quasiracemate-molecular shape controlled molecular recognition
Spaniol, Jacqueline M.,Wheeler, Kraig A.
, p. 64921 - 64929 (2016/07/21)
M. Centnerszwer's seminal 1899 report investigated the stereochemical relationship between optical antipodes of different substances using melting-point behavior. One intriguing melting-point phase diagram produced from this early investigation combined (+)-2-chlorosuccinic acid [(+)-1] and (-)-2-bromosuccinic acid [(-)-2]. While Centnerszwer's data clearly indicates the formation of a quasiracemic phase-i.e., materials constructed from pairs of isosteric molecules of opposite handedness-at the 1:1 component ratio, this material is energetically less favorable than the chiral counterparts. The consequence of this crystal instability is significant as evident by the absence of literature sited crystal structures for the quasiracemic phase (+)-1/(-)-2 and racemates (±)-1 and (±)-2. This study circumvented this challenge by generating multi-molecular assemblies using additional crystallizing agents capable of complementing the hydrogen-bond abilities of succinic acids 1 and 2. Both imidazole (Im) and 4,4′-bipyridyl-N,N′-dioxide (BPDO) served as tailor-made additives that effectively modified the crystal packing landscape of quasiracemate of (+)-1/(-)-2. Combining imidazole with the quasiracemate, racemate, and enantiopure forms of 1 and 2 resulted in crystal structures characterized as molecular salts with layered motifs formed from highly directional N+-H?carboxylate and carboxyl?carboxylate interactions. In contrast to the enantiopure [(+)-1·Im and (-)-2·Im] and racemic [(±)-1·Im and (±)-2·Im] systems, neighboring molecular layers observed in quasiracemate (+)-1/(-)-2·Im are organized by approximate inversion symmetry. Assessment of the crystal packing efficiency for this series of molecular salts via crystal densities and packing coefficients (Ck) indicates imidazole greatly alters the crystal landscape of the system in favor of racemic and quasiracemic crystal packing. A similar desymmetrized crystal environment was also realized for the ternary cocrystalline system of (+)-1/(-)-2·BPDO where the components organize via N+-O-?carboxyl contacts. This study underscores the importance of molecular shape to molecular recognition processes and the stabilizing effect of tailor-made additives for creating new crystalline phases of previously inaccessible crystalline materials.
