Resolution of 4-(1-hydroxy-2,2,2-trifluoroethyl)phenol and its derivatives by lipase-catalyzed enantioselective alcoholysis

Lipase LIP from Pseudomonas aeruginosa,one of nine commercially available hydrolytic enzymes, catalyzed the enantioselective alcoholysis of racemic 4-(1-acetoxy-2,2,2-trifluoroethyl)phenyl acetate with n-butanol, affording (S)-4-(1-hydroxy-2,2,2-trifluoroethyl)phenol at >99% e.e. (E = >100). Moreover, it also showed high enantioselectivity (E = >100) for the alcoholysis of the racemic o-substituted isomer, 2-(1-acetoxy-2,2,2-trifluoroethyl)phenyl acetate.     

Hydrolytic resolution of (R,S)-naproxen 2,2,2-trifluoroethyl thioester by Carica papaya lipase in water-saturated organic solvents

For the first time, the Carica papaya lipase (CPL) stored in crude papain is explored as a potential enantioselective biocatalyst for obtaining chiral acids from their racemic thioesters. Hydrolytic resolution of (R,S)-naproxen 2,2,2-trifluoroethyl thioester in water-saturated organic solvents is employed as a model system for studying the effects of temperature and solvents on lipase activity and enantioselectivity. An optimal temperature of 60 degrees C, based on the initial rate of (S)-thioester and a high enantiomeric ratio (i.e., E-value defined as the ratio of initial rates for both substrates) of >100 at 45 degrees C in isooctane, is obtained. Kinetic analysis, considering product inhibition and enzyme deactivation, is also performed, showing agreement between the experimental and best-fit conversions for (S)-thioester. A comparison of the kinetic and thermodynamic behaviors of CPL and Candida rugosa lipase (CRL) in isooctane and cyclohexane indicates that both lipases are very similar in terms of thermodynamic parameters DeltaDeltaH and DeltaDeltaS, initial rate of (S)-substrate, and E-value when (R,S)-naproxen 2,2,2-trifluoroethyl thioester or ester is employed as substrate.     

1-chloro-2,2,2-trifluoroethyl radical: Formation from halothane by human cytochrome P-450 in reconstituted vesicles and binding to phospholipids

We report the first complete structural characterization of a metabolically-produced halocarbon radical bound to a phospholipid. Human cytochrome P-450 and NADPH cytochrome P-450 reductase were reconstituted into vesicles composed of dioleoylphosphatidylcholine and egg phosphatidylethanolamine. The vesicles were incubated under argon with NADPH and [¹⁴C]-halothane (1-[¹⁴C]-2-bromo-2-chloro-1,1,1-trifluoroethane), the dioleoylphosphatidylcholine fraction was isolated and subjected to transesterification. Separation of the resulting fatty acid methyl esters resulted in one radioactive fraction which gas chromatography-mass spectrometry revealed to be a mixture of 9- and 10-(1-chloro-2,2,2-trifluoroethyl)-stearate methyl ester.     

Synthesis of 2-amino-6-(4-[11C]methoxyphenylthio)-9-[2-(phosphonomethoxy)ethyl]purine bis(2,2,2-trifluoroethyl) ester as a novel potential PET gene reporter probe for HBV and HSV-tk in cancers

Acyclic nucleoside 2-amino-6-(4-methoxyphenylthio)-9-[2-(phosphonomethoxy)ethyl]purine bis(2,2,2-trifluoroethyl) ester (ABE, 1) is a new hepatitis B virus (HBV) specific antiviral reagent and shows high anti-HBV activity. Carbon-11 labeled ABE may serve as a novel reporter probe for positron emission tomography (PET) to image HBV and herpes simplex virus thymidine kinase (HSV-tk) in cancers. The radiolabeling precursors 2-amino-6-(4-hydroxyphenylthio)-9-[2-(phosphonomethoxy)ethyl]purine bis(2,2,2-trifluoroethyl) ester (10) and 2-N-Boc protected analogue 2-N-bis(Boc)amino-6-(4-hydroxyphenylthio)-9-[2-(phosphonomethoxy)ethyl]purine bis(2,2,2-trifluoroethyl) ester (12), and the reference standard ABE were synthesized from bis(trifluoroethyl) (2-iodoethoxy)methylphosphonate (5), guanine (6), and 2-amino-6-chloropurine (8). The target radiotracer 2-amino-6-(4-[11C]methoxyphenylthio)-9-[2-(phosphonomethoxy)ethyl]purine bis(2,2,2-trifluoroethyl) ester ([11C]ABE, [11C]1) was prepared by O-[11C]methylation of the unprotected HO-precursor 10, or 2-N-Boc protected HO-precursor 12 with [11C]methyl triflate followed by a quick deprotection reaction, and isolated by solid-phase extraction (SPE) purification in 40-55% radiochemical yields.     

Long-chain ethers as solvents can amplify the enantioselectivity of the Carica papaya lipase-catalyzed transesterification of 2-(substituted phenoxy)propanoic acid esters

The enantioselectivity of the transesterification of the 2,2,2-trifluoroethyl esters of 2-(substituted phenoxy)propanoic acids, as catalyzed by the lipase from Carica papaya, was greatly improved by using long-chain ethers, such as di-n-hexyl ether, as solvents instead of the conventional diisopropyl ether. Thus, for example, the E value was enhanced from 21 [in diisopropyl ether (0.8 ml)] to 57 [in di-n-hexyl ether (0.8 ml)] in the reaction of 2,2,2-trifluoroethyl(RS)-2-phenoxypropanoate (0.1 mmol) with methanol (0.4 mmol) in the presence of the plant lipase preparation (10 mg); it was also improved from 13 (in diisopropyl ether) to 44 (in di-n-hexyl ether) in the reaction of 2,2,2-trifluoroethyl(RS)-2-(2-chlorophenoxy)propanoate with methanol under the same reaction conditions.     

A New Phosphorylating Agent,Di(2,2,2-Trifluoroethyl) Trimethylsilyl Phosphite. Its Application in Dna Synthesis by The Phosphotriester Approach

Abstract

A new phosphorylating agent, di(2,2,2-trifluoro-ethyl) trimethylsilyl phosphite, has been prepared and is proved to be a useful agent for the phosphorylation of the 3′-hydroxyl group of deoxyribonucleosides in the absence of coupling agents. The resulting deoxyribonucleoside 3′-(2,2,2-trifluoroethyl) phosphates are key intermediates for the synthesis of deoxyribooligonucleotides by the phospho-triester approach.     

Enantioselective hydrolysis of (R,S)-naproxen 2,2,2-trifluoroethyl ester in water-saturated solvents via lipases from Carica pentagona Heilborn and Carica papaya

A crude lipase prepared from Carica pentagona Heilborn latex was explored as an effective enantioselective biocatalyst for the hydrolytic resolution of (R,S)-naproxen 2,2,2-trifluoroethyl ester in water-saturated organic solvents. Comparisons of the enzyme performance with that from Carica papaya lipase indicated that both lipases showed low tolerance to the hydrophilic solvent and were inhibited by (S)-naproxen and 2,2,2-trifluoroethanol. Improvements on the enzyme activity and enantioselectivty were demonstrated when both lipases in partially purified forms were employed. By using the thermodynamic analysis, the enantiomeric discrimination was mainly driven by the difference of activation enthalpy for all reaction systems except for employing Carica papaya lipase as the biocatalyst for (R,S)-fenoprofen 2,2,2-trifluoroethyl thioester.     

(3R)-4-[(3R)-3-Amino-4-(2,4,5-trifluorophenyl)butanoyl]-3-(2,2,2-trifluoroethyl)-1,4-diazepan-2-one, a selective dipeptidyl peptidase IV inhibitor for the treatment of type 2 diabetes

Replacement of the triazolopiperazine ring of sitagliptin (DPP-4 IC(50)=18nM) with 3-(2,2,2-trifluoroethyl)-1,4-diazepan-2-one gave dipeptidyl peptidase IV (DPP-4) inhibitor 1 which is potent (DPP-4 IC(50)=2.6nM), selective, and efficacious in an oral glucose tolerance test in mice. It was selected for extensive preclinical development as a potential back-up candidate to sitagliptin.     

2-(2,2,2-Trifluoroethyl)-5,6-dichlorobenzimidazole derivatives as potent androgen receptor antagonists

The synthesis and in vivo SAR of N-benzyl, N-aceto, and N-ethylene ether derivatives of 2-(2,2,2-trifluoroethyl)-5,6-dichloro-benzimidazole as novel androgen receptor antagonists are described. SAR studies led to the discovery of 4-bromo-benzyl benzimidazole 17 as a more potent androgen receptor antagonist in the rat prostate (ID(50)=0.13mg/day), compared with bicalutamide (ID(50)=0.23mg/day).     

Investigations on fungicides: XIV. Fungitoxicity of N-(2,2,2–trichloro-1–methoxyethyl)-formamide and related compounds

From a study of forty compounds related to the systemic fungicide N,N'-bis(1–formamido-2,2,2–trichloroethyl)-piperazine, known as triforine (CELAW524), it was found that a new compound, N-(2,2,2–trichloro-1–methoxyethyl)-formamide, controls Erysiphe graminis on wheat when applied to the roots in sand. A number of N-(2,2,2–trichloro-1–aryloxyethyl)-form-amides and alkyl N-(2,2,2–trichloro-1–arylaminoethyl)-carbamates protect broad beans against Uromyces fabae and wheat against Erysiphe graminis; some of these formamides show slight activity when applied to plant roots.     

Determination of the optical purity of threonine and hydroxyproline by capillary gas chromatography on a chiral stationary phase

Summary Experimental conditions for the derivatization and resolution by GLC of all stereoisomers of threonine and 4-hydroxyproline are reported. Threonine was in two steps converted toN,O-bisisobutoxycarbonyl 2,2,2-trifluoroethyl ester derivatives, the second of which was performed under anhydrous conditions. As such the enantiomers could pairwise be separated by capillary gas chromatography on a Chirasil-Val column. SinceL- andD-threonine eluted much earlier than the corresponding allo forms, quantitative determination of the allothreonine content inD- orL-threonine down to the one percent level could be simply accomplished but also enantiomeric impurities could be determined. Unlike for threonine, the corresponding 4-hydroxyproline isomers could not all be resolved asN,O-bisisobutoxycarbonyl 2,2,2-trifluoroethyl esters on this column. Although diastereomers could still be separated, the allo pair cochromatographed and the resolution for theL- andD-isomers was low. Complete separation of the 4-hydroxyproline isomers could be accomplished asN,O-bisprotected isobutyl amides, the formation of which required three derivatization steps. These were used for the determination of allohydroxyproline.     

Tranylcypromine and 6-trifluoroethyl thienopyrimidine hybrid as LSD1 inhibitor

Tranylcypromine moiety extracted from LSD1 inhibitors and 6-trifluoroethyl thienopyrimidine moiety from menin-MLL1 PPI inhibitors were merged to give new chemotypes for medicinal chemistry study. Among 15 new compounds prepared in this work, some exhibited nanomolar LSD1 activity and good selectivity over MAO-A/B, low micromolar menin-MLL1 PPI inhibitory activity, as well as submicromolar MV4-11 antiprofilative activities. Intracellular LSD1 engagement of compounds with higher enzymatic and antiproliferative activities was confirmed by CD86 mRNA up-regulation experiments.     

Synthesis and characterization of propyl O-β-d-galactopyranosyl-(1→4)-O-β-d-galactopyranosyl-(1→4)-α-d-galactopyranoside

Allyl 4-O-(4-O-acetyl-2-O-benzoyl-3,6-di-O-benzyl-β-d-galactopyranosyl)-2-O-benzoyl-3,6-di-O-benzyl-α-d- galactopyranoside was O-deallylated to give the 1-hydroxy derivative, and this was converted into the corresponding 1-O-(N-phenylcarbamoyl) derivative, treatment of which with dry HCl produced the α-d-galactopyranosyl chloride. This was converted into the corresponding 2,2,2-trifluoroethanesulfonate, which was coupled to allyl 2-O-benzoyl-3,6-di-O-benzyl-α-d-galactopyranoside, to give crystalline allyl 4-O-[4-O-(4-O-acetyl-2-O-benzoyl-3,6-di-O-benzyl-β-d-galactopyranosyl)-2-O-benzoyl-3,6-di- O-benzyl-β-d-galactopyranosyl]-2-O-benzoyl-3,6-di-O-benzyl-α-d-galactopyranoside (15) in 85% yield, no trace of the α anomer being found. The trisaccharide derivative 15 was de-esterified with 2% KCN in 95% ethanol, and the product O-debenzylated with H₂-Pd, to give the unprotected trisaccharide. Alternative sequences are discussed.     

Specificity of Candida antarctica lipase B (SP 435) in the presence of lipase A in a double enantioselective transesterification

Summary In the lipase-catalyzed double enantioselective transesterification between the meso-diol 1 and the racemic 2,2,2-trifluoroethyl 2-chloropropanoate (rac-2) by the immobilized lipase preparation SP 382 from Candida antarctica, consisting of the components A and B, component B only is responsible for the enantioselectivity.     

Synthesis of the manganese-monocarbollide dianion [1-NHBu-2,2,2-(CO)3-closo-2,1-MnCB10H10]: Reactions with transition metal cations

Reaction of [Mn(NCMe)₃(CO)₃][PF₆] with Li₃[7-NHBu^t-nido-7-CB₁₀H₁₀] in THF (THF = tetrahydrofuran) affords the twelve-vertex manganacarborane dianion [1-NHBu^t-2,2,2-(CO)₃-closo-2,1-MnCB₁₀H₁₀]²⁻, isolated as the bis-[N(PPh₃)₂]⁺ salt (5a). This species reacts with {Pt(dppe)}²⁺ (dppe = Ph₂PCH₂CH₂PPh₂) to afford the bimetallic complex [1-NH₂Bu^t-2,3-{Pt(dppe)}-2,2,2-(CO)₃-closo-2,1-MnCB₁₀H₉] (7) which has an Mn-Pt bond. In contrast, with {Cu(PPh₃)}⁺ the anion of 5a yields a CuMnCu trimetallic compound [1-{NH(Bu^t)Cu(PPh₃)}-2,3,7-{Cu(PPh₃)}-3,7-(μ-H)₂-2,2,2-(CO)₃-closo-2,1-MnCB₁₀H₈] (8) in which one of the Cu centers is bonded to Mn, whilst the other is attached to the pendant NHBu^t group. Upon treatment with Ag⁺, compound 5a is oxidized giving the very unusual Mn(III)-carbonyl complex [1,2-μ-NHBu^t-2,2,2-(CO)₃-closo-2,1-MnCB₁₀H₁₀] (9a) in which the carborane ligand formally acts as an eight-electron donor to manganese. The novel structural features of compounds 7, 8, and 9a have been confirmed by X-ray diffraction studies.     

Synthesis and matched molecular pair analysis of covalent reversible inhibitors of the cysteine protease CPB

Cysteine protease B (CPB) can be targeted by reversible covalent inhibitors that could serve as antileishmanial compounds. Here, sixteen dipeptidyl nitrile derivatives were synthesized, tested against CPB, and analyzed using matched molecular pairs to determine the effects of stereochemistry and p-phenyl substitution on enzyme inhibition. The compound (S)-2-(((S)-1-(4-bromophenyl)-2,2,2-trifluoroethyl)amino)-N-(1-cyanocyclopropyl)-3-phenylpropanamide (5) was the most potent CPB inhibitor (pKi = 6.82), which was also selective for human cathepsin B (pKi < 5). The inversion of the stereochemistry from S to R was more detrimental to potency when placed at the P2 position than at P3. The p-Br derivatives were more potent than the p-CH₃ and p-OCH₃ derivatives, probably due to intermolecular interactions with the S3 subsite.     

A rapid sensitive assay for phosphatidate phosphohydrolase.

For a purified preparation of the soluble form of phosphatidate phosphohydrolase (EC 3.1.3.4) from guinea pig cerebral cortex, 1-O-alkyl-rac-glycerol 3-phosphate was found to be accepted as a substrate. This substrate analog was tritium-labeled in order to serve in a rapid sensitive assay for the enzyme, in which labeled 1-alkyl glycerol is released. Heat denaturation and enzyme activity dependence on pH indicated that 1-O-alkyl-rac-glycerol 3-phosphate phosphohydrolase and phosphatidate phosphohydrolase activities in the preparation are attributable to the same enzyme. 1-O-Alkyl-rac-glycerol 3-phosphate was hydrolyzed with a V_max of 1.7 nmol min^?1 mg^?1 of protein and a K_m of 270 μm.     

New route to the 5-((arylthio- and heteroarylthio)methylene)-3-(2,2,2-trifluoroethyl)-furan-2(5H)-ones—Key intermediates in the synthesis of 4-aminoquinoline γ-lactams as potent antimalarial compounds

In this Letter we report on a multi-step synthesis of 5-((arylthio- and heteroarylthio)-methylene)-3-(2,2,2-trifluoroethyl)furan-2(5H)-ones starting from γ-keto thiolester or γ-keto carboxylic acid. The key intermediate γ-lactones were then reacted with 4-aminoquinoline-derived amines via ring opening—ring closure (RORC) process affording the corresponding γ-hydroxy-γ-lactams in moderate to good yields. In vitro antimalarial activity of the resulting new 4-aminoquinoline γ-lactams were evaluated against Plasmodium falciparum clones of variable sensitivity (3D7 and W2) and were found to be active in the range of 89–1600 nM with good resistance index and did not show cytotoxicity in vitro when tested against human umbilical vein endothelial cells (HUVEC) up to concentration of 50 μM.     

The 1,1-Dianisyl-2,2,2-trichloroethyl Moiety as a New Protective Group for the Synthesis of Dinucleostde Trifluoromethylphosphonates

Abstract

The new 1,1-Dianisyl-2,2,2-trichloroethyl moiety (DATE) is used as an acid and base stable protective group for nucleosides. 5′-O-DATE-thymidine and 3′-O-acetyl-thymidine are phosphorylated with CF₃P(NR₂)₂ to the corresponding thymidine trifluoromethylphosphonous amidites. These building blocks are coupled with appropriate protected thymidines to a dinucleotide trifluoromethylphosphonate.

     

Quantitative methods for determining the points of O-(carboxymethyl) substitution in O-(carboxymethyl)-guar

Two methods are described for locating the O-(carboxymethyl) groups in O-(carboxymethyl)guar. In Method I, O-(carboxymethyl)guar was depolymerized by methanolysis, the O-(carboxymethyl) groups were reduced, and the mixture of methyl glycosides and O-(2-hydroxyethyl)-substituted methyl glycosides was converted into a mixture of per-O-acetylated alditols and partially O-(2-acetoxyethyl)ated, partially O-acetylated alditols. Analysis of these alditols by gas-liquid chromatography-mass spectrometry allowed the positions of substitution of the O-(carboxymethyl) groups on the galactosyl groups and mannosyl residues to be determined. However, this method did not distinguish between O-(carboxymethyl) substitution on 4-linked and 4,6-linked mannosyl residues. This limitation was overcome by the more-detailed analysis provided by Method II, in which O-(carboxymethyl)guar was carboxyl-reduced, the product methylated, the glycosyl residues hydrolyzed, the sugars reduced, and the alditols acetylated to yield a mixture of partially O-acetylated, partially O-methylated alditols and partially O-acetylated, partially O-(2-methoxyethyl)ated, partially O-methylated alditols. These derivatives, when separated and quantitated by g.l.c., and identified by g.l.c.-m.s., gave a quantitative measure of every type of carboxymethyl substitution in guar.