A facile synthesis of unsymmetrical ureas

Structure-based discovery of CFTR potentiators and inhibitors

The cystic fibrosis transmembrane conductance regulator (CFTR) is a crucial ion channel whose loss of function leads to cystic fibrosis, whereas its hyperactivation leads to secretory diarrhea. Small molecules that improve CFTR folding (correctors) or function (potentiators) are clinically available. However, the only potentiator, ivacaftor, has suboptimal pharmacokinetics and inhibitors have yet to be clinically developed. Here, we combine molecular docking, electrophysiology, cryo-EM, and medicinal chemistry to identify CFTR modulators. We docked ∼155 million molecules into the potentiator site on CFTR, synthesized 53 test ligands, and used structure-based optimization to identify candidate modulators. This approach uncovered mid-nanomolar potentiators, as well as inhibitors, that bind to the same allosteric site. These molecules represent potential leads for the development of more effective drugs for cystic fibrosis and secretory diarrhea, demonstrating the feasibility of large-scale docking for ion channel drug discovery.

Structure-based discovery of CFTR potentiators and inhibitors

The cystic fibrosis transmembrane conductance regulator (CFTR) is a crucial ion channel whose loss of function leads to cystic fibrosis, while its hyperactivation leads to secretory diarrhea. Small molecules that improve CFTR folding (correctors) or function (potentiators) are clinically available. However, the only potentiator, ivacaftor, has suboptimal pharmacokinetics and inhibitors have yet to be clinically developed. Here we combine molecular docking, electrophysiology, cryo-EM, and medicinal chemistry to identify novel CFTR modulators. We docked ~155 million molecules into the potentiator site on CFTR, synthesized 53 test ligands, and used structure-based optimization to identify candidate modulators. This approach uncovered novel mid-nanomolar potentiators as well as inhibitors that bind to the same allosteric site. These molecules represent potential leads for the development of more effective drugs for cystic fibrosis and secretory diarrhea, demonstrating the feasibility of large-scale docking for ion channel drug discovery.

Synthesis of Asymmetric Urea Derivatives from COS and Amines: Substrate Selection, Scope Studies, and Mechanism Investigation

A series of asymmetric ureas were synthesized by a one-pot reaction of amines and carbonyl sulfide (COS) under catalyst-free conditions. The highly selective synthesis of asymmetric urea was successfully achieved by the use of weakly nucleophilic aromatic amines and highly nucleophilic secondary aliphatic amines. Moreover, a reaction mechanism was proposed based on the detailed NMR and FTIR study. This efficient synthetic methodology provides a mild and selective method for synthesizing asymmetric urea derivatives.

A decade review of triphosgene and its applications in organic reactions

This review article highlights selected advances in triphosgene-enabled organic synthetic reactions that were reported in the decade of 2010-2019. Triphosgene is a versatile reagent in organic synthesis. It serves as a convenient substitute for the toxic phosgene gas. Despite its first known preparation in the late 19th interestingly began only three decades ago. Despite the relatively short history, triphosgene has been proven to be very useful in facilitating the preparation of a vast scope of value-added compounds, such as organohalides, acid chlorides, isocyanates, carbonyl addition adducts, heterocycles, among others. Furthermore, applications of triphosgene in complex molecules synthesis, polymer synthesis, and other techniques, such as flow chemistry and solid phase synthesis, have also emerged in the literature.

Synthesis of Fluorinated Dialkyl Carbonates from Carbon Dioxide as a Carbonyl Source

Fluorinated dialkyl carbonates (DACs), which serve as environmentally benign phosgene substitutes, were produced successfully from carbon dioxide either directly or indirectly. Nucleophilic addition of 2,2,2-trifluoroethanol to carbon dioxide and subsequent reaction with 2,2,2-trifluoroethyltriflate (3 a) afforded bis(2,2,2-trifluoroethyl) carbonate (1) in up to 79 % yield. Additionally, carbonate 1 was obtained through the stoichiometric reaction of 3 a and cesium carbonate. Although bis(1,1,1,3,3,3-hexafluoro-2-propyl) carbonate (4) was difficult to obtain by either of the above two methods, it could be synthesized through the transesterification of carbonate 1.

A novel route to unsymmetrical disubstituted ureas and thioureas by HMPA catalyzed reductive alkylation with trichlorosilane

A HMPA catalyzed reductive alkylation of ureas and thioureas with trichlorosilane under mild reaction conditions has been developed.

Synthesis of unsymmetrical urea derivatives via one-pot sequential three-component reactions of cyclic 2-diazo-1,3-diketones, carbodiimides, and 1,2-dihaloethanes

An effective and operationally simple one-pot strategy has been developed for the synthesis of unsymmetrical urea derivatives via sequential three-component reactions of cyclic 2-dizao-1,3-diketones with carbodiimides and 1,2-dihaloethane.

An Old Story in the Parallel Synthesis World: An Approach to Hydantoin Libraries

An approach to the parallel synthesis of hydantoin libraries by reaction of in situ generated 2,2,2-trifluoroethylcarbamates and α-amino esters was developed. To demonstrate utility of the method, a library of 1158 hydantoins designed according to the lead-likeness criteria (MW 200-350, cLogP 1-3) was prepared. The success rate of the method was analyzed as a function of physicochemical parameters of the products, and it was found that the method can be considered as a tool for lead-oriented synthesis. A hydantoin-bearing submicromolar primary hit acting as an Aurora kinase A inhibitor was discovered with a combination of rational design, parallel synthesis using the procedures developed, in silico and in vitro screenings.

α-Glucosidase inhibitory activity and cytotoxic effects of some cyclic urea and carbamate derivatives

The inhibitory activities of selected cyclic urea and carbamate derivatives (1-13) toward α-glucosidase (α-Gls) in in vitro assay were examined in this study. All examined compounds showed higher inhibitory activity (IC₅₀) against α-Gls compared to standard antidiabetic drug acarbose. The most potent was benzyl (3,4,5-trimethoxyphenyl)carbamate (12) with IC₅₀ = 49.85 ± 0.10 µM. In vitro cytotoxicity of the investigated compounds was tested on three human cancer cell lines HeLa, A549 and MDA-MB-453 using MTT assay. The best antitumour activity was achieved with compound 2 (trans-5-phenethyl-1-phenylhexahydro-1H-imidazo[4,5-c]pyridin-2(3H)-one) against MDA-MB-453 human breast cancer cell line (IC₅₀ = 83.41 ± 1.60 µM). Cyclic ureas and carbamates showed promising anti-α-glucosidase activity and should be further tested as potential antidiabetic drugs. The PLS model of preliminary QSAR study indicated that, in planing the future synthesis of more potent compounds, the newly designed should have the substituents capable of polar interactions with receptor sites in various positions, while avoiding the increase of their lipophilicity.

A Facile and Efficient Method for the Formation of Unsymmetrical Ureas Using DABAL-Me3

A practical synthetic method for the formation of unsymmetrical-substituted ureas is described. The synthesis of the unsymmetrical ureas was readily performed from 2,2,2-trichloroethyl carbamate compounds by treatment of amines with bis(trimethylaluminum)-1,4-diazabicyclo[2.2.2]octane (DABAL-Me3). Using this reaction protocol, various trisubstituted and tetrasubstituted ureas were synthesized in high yields. This study offers a promising approach for the facile synthesis of a variety of unsymmetrical ureas from 2,2,2-trichloroethyl carbamates.

2,2,2-Trifluoroethyl Chlorooxoacetate--Universal Reagent for One-Pot Parallel Synthesis of N(1)-Aryl-N(2)-alkyl-Substituted Oxamides

A one-pot parallel synthesis of N(1)-aryl-N(2)-alkyl-substituted oxamides with 2,2,2-trifluoroethyl chlorooxoacetate was developed. The synthesis of a library of 45 oxamides revealed higher efficiency of this reagent over the known ethyl chlorooxoacetate. The reagent was successfully used to prepare the known oxamide-containing HIV entry inhibitors.

Cu(II)-promoted methanolysis of N,N-bis(2-picolyl)carbamates: rate-limiting metal ion delivery of coordinated alcoholate nucleophile followed by fast partitioning of a tetrahedral intermediate

Five O-aryl/alkyl N,N-bis(2-picolyl)carbamates were prepared with the O-aryl/alkyl portions being p-nitrophenoxy, m-nitrophenoxy, trifluoroethoxy, methoxy, and isopropoxy (4a,b,c,d,e, respectively) and the kinetics and reaction products of their methanolysis reactions in the presence of Cu(O₃SCF₃)₂ determined. The catalyzed reactions have maximal rates for each substrate at a 1:1 ratio of [4]:[Cu²⁺] at (s)(s)pH 7.9, where the active forms are Cu(II):4:(⁻OCH₃). The reactions are fast, that for the complex of 4a having a t(1/2) of 30 s. The products of the reaction with 4a and 4b arise exclusively from C-OAr cleavage: those with 4d and 4e arise exclusively from C-N cleavage. With 4c, products from both C-O and C-N cleavage are observed in a 2.17:1 ratio. The common mechanism involves rate-limiting delivery of a Cu(II)-coordinated methoxide to the C═O unit to form a tetrahedral intermediate followed by fast partitioning to products by two pathways with relative barriers dependent on the (s)(s)pK(a)(HOAr/HOR). The data allow one to predict an effective (s)(s)pK(a) of ∼15.6 for the (s)(s)pK(a)(NH) of Cu(II):bis(2-picolyl)amine.

Facile one-pot synthesis of 4-substituted semicarbazides

A simple one-pot approach to 4-substituted semicarbazides allowed us to synthesize a 25 member library.

Bis(2,2,2-trifluoroethyl) carbonate as a condensing agent in one-pot parallel synthesis of unsymmetrical aliphatic ureas

One-pot parallel synthesis of unsymmetrical aliphatic ureas was achieved with bis(2,2,2-trifluoroethyl) carbonate. The procedure worked well for both the monosubstituted and functionalized alkyl amines and required no special conditions (temperature control, order, or rate of addition). A library of 96 diverse ureas was easily synthesized.