Showing papers on "Oxazolidine published in 2015"

Synthesis of Enantiopure trans-2,5-Disubstituted Trifluoromethylpyrrolidines and (2S,5R)-5-Trifluoromethylproline

Abstract: Enantiopure trans-2,5-disubstituted trifluoromethylpyrrolidines were prepared on a several gram scale starting from a readily available chiral fluorinated oxazolidine (Fox). A pure oxazolopyrrolidine intermediate could be obtained after an efficient separation by selective diastereomer destruction. The addition of various Grignard reagents on this oxazolopyrrolidine provided disubstituted pyrrolidines with moderate to complete trans diastereoselectivity. The highly valuable compound (2S,5R)-5-trifluoromethylproline could be synthesized from the same oxazolopyrrolidine intermediate via a Strecker-type reaction.

Atropo- and Diastereoselective Construction of Tetracyclic Biphenylazepinium Salts Derived from Aminoalcohols: Use as Catalysts in Enantioselective Asymmetric Epoxidation.

Abstract: A range of new biphenylazepinium salt organocatalysts effective for asymmetric epoxidation has been developed incorporating an additional substituted oxazolidine ring, and providing improved enantiocontrol in alkene epoxidation over the parent structure. Starting from enantiomerically pure aminoalcohols, tetracyclic iminium salts were obtained as single diastereoisomers through an atroposelective oxazolidine formation.

Cross-Aldol Reaction of Isatin with Acetone Catalyzed by Leucinol: A Mechanistic Investigation

Abstract: Comprehensive mechanistic studies on the enantioselective aldol reaction between isatin (1 a) and acetone, catalyzed by L-leucinol (3 a), unraveled that isatin, apart from being a substrate, also plays an active catalytic role. Conversion of the intermediate oxazolidine 4 into the reactive syn-enamine 6, catalyzed by isatin, was identified as the rate-determining step by both the calculations (ΔG≠=26.1 kcal mol−1 for the analogous L-alaninol, 3 b) and the kinetic isotope effect (kH/kD=2.7 observed for the reaction using [D6]acetone). The subsequent reaction of the syn-enamine 6 with isatin produces (S)-2 a (calculated ΔG≠=11.6 kcal mol−1). The calculations suggest that the overall stereochemistry is controlled by two key events: 1) the isatin-catalyzed formation of the syn-enamine 6, which is thermodynamically favored over its anti-rotamer 7 by 2.3 kcal mol−1; and 2) the high preference of the syn-enamine 6 to produce (S)-2 a on reaction with isatin (1 a) rather than its enantiomer (ΔΔG≠=2.6 kcal mol−1).

Asymmetric synthesis of 3-substituted tetrahydro-2-benzazepines.

Abstract: The enantiomerically and diastereomerically pure tricyclic oxazolidine cis-10 was prepared in a five step synthesis starting with 1-bromo-2-iodobenzene. Me3SiCN and allylSiMe3 reacted with cis-10 in the presence of TiCl4 to form the nitrile (3S)-11 and the allyl derivative (3S)-12 with high diastereoselectivity. The hydrogenolytic removal of the chiral auxiliary failed, since the endocyclic benzyl-N-bond was cleaved simultaneously. Therefore the N-(hydroxyethyl)amide of (3S)-12 was transformed into the enamide 27, which was hydrolyzed to afford the secondary amide 28. The enamide strategy to remove the chiral auxiliary from (3S)-11 led to complete racemization due to fast deprotonation in α-position of the cyano moiety. Two pairs of enantiomers 30a-b/ent-30a-b with prototypical σ substituents at the N-atom were prepared. The low σ1 affinity of the tetrahydro-2-benzazepines (ent-30b, Ki = 407 nM) is attributed to the short distance between the two lipophilic aromatic moieties.

Single-component microbubble latent curing solvent-free polyurethane adhesive and preparation method thereof

Abstract: The invention discloses a single-component microbubble latent curing solvent-free polyurethane adhesive. The adhesive is characterized by being prepared from the following components in percentage by weight: 35-75 percent of polyol, 25-65 percent of polyisocyanate, 0.5-15 percent of oxazolidine substances and 0.01-0.15 percent of organic tin catalyst or organic amine catalyst. The polyurethane adhesive has high adhesion strength, proper viscosity, good single-component operating performance and high curing speed, does not contain VOC, and can be used for preventing moisture from directly reacting with NCO to cure and generate carbon dioxide gas and other adverse side reactions since oxazolidine substances are used as a latent curing agent and a water absorbent or an active diluting agent.

Synthesis of tetrahydrothiophene 1,1-dioxides annulated with oxazolidine ring

Abstract: 1,3-Oxazolidines exhibit versatile biological activity (anticancer, antiviral, antibacterial, anxiolytic, neurotropic) and are utilized as chiral precursors in designing optically active natural and synthetic compounds, and also as chiral ligands making possible enantioand diastereoselective processes [1–4]. Derivatives of tetrahydrothiophene 1,1-dioxide (sulfolane) do not occur naturally but are industrially available and can be used as building blocks in the syntheses of diverse biologically active heterocyclic compounds [5– 11]. Earlier only a single attempt was undertaken for annulation of oxazolidine cycle to sulfolane ring (any data confirming the structure of the product are not given) [12]. Therefore it is topical to develop preparation methods for potentially biologically active hexahydrothieno-[3,4-d][1,3]oxazole 5,5-dioxides.

Novel oxazolidine, preparation method, application, and mono-component polyurethane waterproof paint

Abstract: The invention discloses novel oxazolidine, a preparation method, application, and mono-component polyurethane waterproof paint. The novel oxazolidine is named as 4-mehtyl-3-(2-phenylcarbinol)-1,3-oxazolidine. The novel oxazolidine is used as a latent curing agent of the mono-component polyurethane waterproof paint. During the production process of the waterproof paint, the novel oxazolidine is added into the raw materials, one naked hydroxy group of the novel oxazolidine will react with the polyurethane prepolymer formed by the raw materials, thus the novel oxazolidine is grafted to the polyurethane prepolymer, and the novel oxazolidine (latent curing agent) can be more evenly dispersed in the waterproof paint. If the waterproof paint is stored for a long time, the grafted novel oxazolidine will be dissolved out continuously, the stability of the waterproof paint is improved, the latent curing effect is improved, and avoided is the phenomenon that the latent curing agent is precipitated from the mono-component polyurethane waterproof paint or the latent curing agent aggregates in the waterproof paint. After the waterproof paint is used, the quality of the film formed by the waterproof paint is improved.

Crystal structure of γ-ethyl-l-glutamate N-carb-oxy anhydride.

Abstract: In the title compound (alternative name N-carboxy-l-glutamic anhydride γ-ethyl ester), C8H11NO5, the oxazolidine ring is essentially planar, with a maximum deviation of 0.019 (2) A. In the crystal, mol­ecules are linked by N—H⋯O hydrogen bonds between the imino group and the carbonyl O atom in the ethyl ester group, forming a tape structure along the c-axis direction. The oxazolidine rings of adjacent tapes are arranged into a layer parallel to the ac plane. This arrangement is favourable for the polymerization of the title compound in the solid state.

Preparing method of oxazolidine-2-one compounds

Abstract: A preparing method of oxazolidine-2-one compounds is disclosed. The oxazolidine-2-one compounds are prepared by mixing an epoxy compound and a primary amine, adding an ionic liquid, heating and reacting in a CO2 atmosphere, and directly fixing the CO2 by utilizing the epoxy compound as a high-energy molecule platform. The high energy performance of the epoxy compound is fully utilized to activate the CO2 in the method. The method is characterized by no need of separation of intermediate products, small using amount of a catalyst, safe reaction operation, mild conditions, no need of an extra solvent, and environment protection.

Crystal structure of 5-chloro-1,3-bis-[2-(2-oxo-1,3-oxazolidin-3-yl)eth-yl]-1H-benz-imidazol-2(3H)-one.

Abstract: In the title compound, C17H19ClN4O5, the benzimidazole fused-ring system is essentially planar, the maximum deviation from the mean plane being 0.06 (1) A. Both oxazolidine rings are nearly planar, the maximum deviations from the mean planes are 0.071 (13) and 0.070 (10) A. The dihedral angle between the mean planes of the oxazolidine rings is 69.9 (7)°. The benzimidazole mean plane makes the dihedral angles of 43.9 (6) and 45.6 (6)° with the two oxazolidine rings. In the crystal, the mol­ecules are linked together by weak C—H⋯O hydrogen bonds building zigzag tapes running along the c axis. The Cl atom is split over two positions with an occupancy ratio of 0.567 (7):0.433 (7). This means that the reaction yields two isomers, A and B; the A component has the Cl-atom substituent in the 5-position of the benzimidazolone ring and the B component has the Cl atom in the 6-position. The two isomers form the disordered co-crystal, with a nearly half Cl atom in each of them, as indicated by the occupancy ratio. The crystal structure was refined as an inversion twin.

Crystal structure of methyl 3-(3-fluoro­phen­yl)-1-methyl-1,3a,4,9b-tetra­hydro-3H-thio­chromeno[4,3-c]isoxazole-3a-carboxyl­ate

Abstract: In the title compound, C19H18FNO3S, the five-membered oxazolidine ring adopts an envelope conformation with the methine C atom of the fused bond as the flap. Its mean plane is oriented at a dihedral angle of 50.38 (1)° with respect to the fluoro-phenyl ring. The six-membered thio-pyran ring has a half-chair conformation and its mean plane is almost coplanar with the fused benzene ring, making a dihedral angle of 4.94 (10)°. The two aromatic rings are inclined to one another by 85.96 (11)°, and the mean planes of the oxazolidine and thio-pyran rings are inclined to one another by 57.64 (12)°. In the crystal, mol-ecules are linked by C-H⋯π inter-actions, forming a three-dimensional structure.

N-Boc Amines to Oxazolidinones via Pd(II)/Bis-sulfoxide/Broensted Acid Co-Catalyzed Allylic C—H Oxidation.

Abstract: The process leads to formation of oxazolidine structures in moderate yields and good to excellent diastereoselectivity.

Synthesis of Indole-Derived Fluorine-Containing Amino Acids

Abstract: A Bronsted acid promoted direct aminoalkylation of various indoles with trifluoromethyl oxazolidine is described. A catalytic amount of triflic acid provided straightforward access to the corresponding trifluoromethyled amino esters under mild reaction conditions and a short reaction time of 4 h. On further hydrogenolysis and hydrolysis of ester, the synthesis of indole derived unnatural trifluoromethylated amino acids was achieved. Journal of Nature and Science, 1(8):e1 69 , 2015

Relating to treatment of water

Abstract: The present invention relates to water treatment. In one embodiment there is provided a method of treating an aqueous system to inhibit growth of one or more micro-organisms therein and/or to reduce the number of live micro-organisms therein. The method comprises adding treatment agents to said aqueous system and wherein said treatment agents comprise: (a) a phosphonium compound; and (b) an oxazolidine compound.

Atropo- and Diastereoselective Construction of Tetracyclic Biphenylazepinium Salts Derived from Aminoalcohols: Use as Catalysts in Enantioselective Asymmetric Epoxidation.

Abstract: A range of new biphenylazepinium salt organocatalysts effective for asymmetric epoxidation has been developed incorporating an additional substituted oxazolidine ring, and providing improved enantiocontrol in alkene epoxidation over the parent structure. Starting from enantiomerically pure aminoalcohols, tetracyclic iminium salts were obtained as single diastereoisomers through an atroposelective oxazolidine formation.

Method for preparing (2R,4S)-3-Cbz-2,4-diphenyl-1,3-oxazolidine-5-ketone

Abstract: The invention relates to a method for preparing (2R,4S)-3-Cbz-2,4-diphenyl-1,3-oxazolidine-5-ketone and belongs to the technical field of drug intermediate synthesis. The aim about how to improve reacting efficiency and increase the yield without adopting a diethyl ether solvent is achieved. The method comprises the steps that raw materials N-Cbz-L-phenylglycine and benzaldehyde dimethyl acetal are subjected to a condensation reaction in catalyst boron trifluoride diethyl etherate, and after the condensation reaction is finished, a corresponding Rolapitant intermediate type I compound is obtained. No solvent needs to be additionally added, the reaction can be carried out more efficiently, reaction efficiency is improved, the yield of products is guaranteed, and the yield can reach 89% or above.

Enantiospecific Synthesis of (S)‐(—)‐8‐Oxoxylopinine.

Abstract: Key step in the straightforward asymmetric synthesis of the protoberberine precursor (S)-(-)-8-oxoxylopinine (I) is the addition of 6,7-dimethoxy-3,4-dihydroisoquinoline to an in situ generated benzylic anion bearing a (S)-alaninol derived oxazolidine as chiral auxiliary.

Method of synthesizing 4-{4-[(5S)-5-(aminomethyl)-2-oxo-1,3-oxazolidine-3-yl]phenyl}morpholine-3-one

Abstract: The invention provides a method of synthesizing 4-{4-[(5S)-5-(aminomethyl)-2-oxo-1,3-oxazolidine-3-yl]phenyl}morpholine-3-one, wherein the method includes the steps of (1) performing a one-step cyclization reaction to an intermediate N-(4-aminophenyl)-2-(2-haloethyoxyl)acetamide to prepare 4-(4-aminophenyl)-3-morpholinone; and (2) carrying out a ring-opening reaction with an epoxy compound, a substitution reaction, a cyclization reaction and like to the 4-(4-aminophenyl)-3-morpholinone to obtain the key intermediate, 4-{4-[(5S)-5-(aminomethyl)-2-oxo-1,3-oxazolidine-3-yl]phenyl}morpholine-3-one, of rivaroxaban. The method is high in yield, is less in pollution, is free of an expensive metal palladium for performing nitro-reduction during the process and is suitable for industrial production.

Synthesis of Oxazolidine‐2,4‐diones by a Tandem Phosphorus‐Mediated Carboxylative Condensation—Cyclization Reaction Using Atmospheric Carbon Dioxide.

Abstract: Oxazolidine-2,4-diones [(IV), (VIII), and (X)] are conveniently synthesized via title tandem reaction in one-pot fashion using carbon dioxide under atmospheric pressure and transition-metal free conditions.