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Polycyclic xanthones are secondary metabolites from actinomycetes and cervinomycin A and B are bioactive 26-membered polycyclic xanthones from Streptomyces sp. CPCC 204980. Herein, we report cervinomycins C1-4 (1–4) from the same strain. The structures of 1–4 were determined by 1D- and 2D-NMR, or single-crystal X-ray diffraction. Compounds 1–4 feature the open or loss of A (oxazolidine) ring in their angular polycyclic framework compared with cervinomycin B. Compounds 1–4 showed potent cytotoxicity against human cancer cell lines HCT116 and BxPC-3, with IC50 at 0.9–801.0 nM and strong anti-Gram-positive bacterial activity.

(E)-3,3,3-Trichloro-1-nitroprop-1-ene undergoes [3+2] cycloaddition reaction with N-aryl(pyridin-3-yl) nitrones under mild conditions. The reaction is fully regio- and stereoselective and gives expected nitro-substituted nicotine analogs with 3,4-cis-4,5-trans-stereoconfiguration.

New 3’-(4-chlorophenyl)-5’,5’-dimethyl-2’-oxospiro[(2H)-chromene-2,4’-1,3-oxazolidine] was synthesized to study the donor influence of the chlorine atom at the N-phenyl substituent on the structure and photochromic properties of 1,3-oxazolidine-containing spiropyrans. Photochemical properties of synthesized 1,3-oxazolidine derivatives were studied at room temperature in toluene. The X-ray diffraction parameters for the new compound were compared with the data obtained earlier for similar spiropyrans.

The d- and l-enantiomers of the ternary complex [Cu(phen)(ala)(H2O)]NO3 [phen = 1,10-phenanthroline; ala = alanine; l-enantiomer (1a); d-enantiomer (1b)] both undergo an aldol-type condensation with formaldehyde under mild acidic conditions to yield racemic rac-[Cu(phen)(4MeOCA)(H2O)(NO3)] (2) (4MeOCA = 4-methyl-oxazolidine-4-carboxylate). The precursors and the products were characterized by circular dichroism, FTIR, UV–Vis, fluorescence spectroscopy, molar conductivity and electrospray ionization mass spectrometry. The racemic nature of the product was established by X-ray crystallography . In the crystal structure, the copper atom has a tetragonally elongated octahedral geometry in which the water and an oxygen atom of a nitrate group are mutually trans. A possible mechanism for the racemization of the ligand is proposed.

Plasma amine oxidase (PAO), which is also designated as semicarbazide-sensitive amine oxidase (SSAO), copper-containing amine oxidase 3 (AOC3), or vascular adhesion protein-1 (VAP-1), catalyzes the oxidative deamination of primary amines to aldehydes using copper and a quinone as cofactors. Because it participates in the transmigration of inflammatory cells through the blood vessels into the tissue, PAO is attributed an important role in inflammatory diseases. Therefore, inhibitors of this enzyme could lead to new therapeutics for the treatment of inflammation-related conditions. Assays for the evaluation of PAO inhibitors usually measure the conversion of benzylamine to benzaldehyde by UV spectroscopy. We have developed a test system with the new substrate 6-(5-phenyl-2H-tetrazol-2-yl)hexan-1-amine, monitoring the formation of the enzyme product 6-(5-phenyl-2H-tetrazol-2-yl)hexanal by reversed phase HPLC with UV detection. Since this compound only eluted with poor peak shape due to hydrate formation in the aqueous mobile phase, it was derivatized with tris(hydroxymethyl)aminomethane (TRIS) under mild conditions to an oxazolidine prior HPLC analysis. The validation of the method revealed that the new substrate was bound with higher affinity to PAO and converted with higher velocity than the standard substrate benzylamine.

Global efforts to find renewable feed stocks for the chemical industry are aimed at replacing fossil reserves and a reduction in global warming by employing environmently friendly technologies (green chemistry approaches) for specialty chemical manufacturing. Cardanol obtained from “Cashew Nut Shell Liquid” (CNSL) is a renewable resource of immense potential. Present work describes the synthesis of bio-based polyol for rigid polyurethane foam via step wise oxazolidine route. Synthesized polyol was characterized by spectral analysis. The foaming characteristics were studied, and the polyol were successfully used in making rigid Polyurethane foams with good mechanical, thermal and fire properties.

Thione–thiol transformation of thiazolidine-2-thione and oxazolidine-2-thione via direct transition, as well as self-assisted and water-assisted tautomerization was investigated using the quantum-chemical calculations. The thione complexes are more stable than the corresponding thiols. The calculations revealed that the proton transfer energy barriers are significantly lower in the presence of water molecules. Direct transition is more difficult than the water-assisted and self-assisted processes. The cooperative effects in terms of additive interaction energies and cooperativity factors of the clusters are measured and discussed. The electronic properties of the complexes are analyzed using parameters derived from atoms-in-molecules and natural bond orbital methodologies. Also, the influence of the hydrogen bond on the molecular and topological properties, as well as nuclear magnetic resonance one- and two-bond spin–spin coupling constants are investigated.

Simple and efficient strategies towards the synthesis of substituted spiro-oxindole and oxazolidine systems by one-pot multi-component catalyst-free reactions utilising aryl aldehydes and α-amino acids have been developed. Owing to their complicated structure and ring strain spiro-oxindole moieties are not easily synthesised. In either route 1,3-dipolar cycloadditions involving non-stabilised azomethine ylides as intermediates, generated in situ from amino acids and aldehydes, with the dipolarophile present in the reaction mixture viz. (E)-β-nitrostyrene, were utilised. The route to substituted oxazolidines involved cycloaddition to the C=O bond of a second molecule of the aldehyde.

A number of compounds have been prepared in order to improve pharmacological roles of antihyperglycemic activity. In the present paper, a series of 3-benzyl-2-(4'-substituted phenyl)-4(5H)-(4″-nitrophenyl amino)-1,3-oxazolidines (6a-e) were tested against hyperglycemia. Their antihyperglycemic activity was evaluated by streptozotocin (STZ) and sucrose-loaded (SLM) models. Compounds 6a, b, c, d, and e displayed significant reductions in blood glucose in the streptozotocin and sucrose loaded rat models. The purity of the synthesized compounds was characterized by means of IR, (1)H-NMR, mass spectral and elemental analysis.

A new series of 2-aryl, 3-benzyl-(1,3-oxazolidine or 1,3-thiazolidine)-4-ones, possessing a methylsulfonyl pharmacophore, were synthesized to evaluate their biological activities as selective cyclooxygenase-2 (COX-2) inhibitors. In vitro COX-1 and COX-2 isozyme inhibition studies were performed to acquire structure-activity relationship data with respect to the point that molecular modeling studies showed that designed compounds bind in the primary binding site such that the C-2 para-SO2Me substituent inserts into the 2° pocket present in COX-2 enzyme. COX-1 and COX-2 inhibition studies showed that all compounds were selective inhibitors of the COX-2 isozyme with IC50 values in the highly potent 0.21 to 0.34 μM range, and COX-2 selectivity indexes in the 222.3 to >476 range. 3-Benzyl-2-(4-methylsulfonylphenyl)-1,3-oxazolidine-4(5H)-one was identified as the most potent (IC50 = 0.21 μM) and selective (S.I. > 476) COX-2 inhibitor among the synthesized compounds. It also was a more selective COX-2 inhibitor than the parent reference compound celecoxib (S.I. > 403).

A method has been developed and validated for the identification and quantification of p-synephrine in Citrus aurantium L. products. The approach comprises GC-FID analysis followed by GC-MS confirmation after clean-up by solid phase extraction with a strong cation-exchange phase and derivatization with cyclohexanone. Oxazolidine derivative of p-synephrine was subjected to analysis by nuclear magnetic resonance (1H and 13C NMR), GC-FID and GC-MS. The GC method was validated and was found to be linear in the range of 125–500 mg%. Intra-day and inter-day precisions were 3.60 and 3.59%, respectively. Mean recovery from extract of C. aurantium was 78.1 ± 3.64%. The selectivity of the method was further improved by confirmation of oxazolidine derivative of p-synephrine by GC-MS.

The reactions of CO2 with oxirane to produce cyclic carbonate, and with aziridine to afford oxazolidine have been of interest as a useful method for its fixation by a chemical process. Highly efficient processes employing recyclable CO2-phlilic homogeneous catalyst were devised for environmentally benign synthesis of cyclic carbonates and oxazolidinones under supercritical CO2 without any organic solvent. These processes represent pathways for greener chemical fixations of CO2 to afford industrial useful materials such as organic carbonates and oxazolidinones with great potential applications.

The influence of 1,3-oxazolidine and 1,3-oxathiolane fragments in substituted alkenes on the direction of their catalytic reaction with diazomethane has been investigated. The olefins bearing an oxazolidine substituent in the α- or γ-position and an oxathiolane substituent in the γ-position relative to the C=C bond react with diazomethane in the presence of Pd(acac)2 selectively resulting in cyclopropanation products. The use of Cu(OTf)2 does not result in cyclopropanation; however Cu(OTf)2 catalyzes the reaction of diazomethane with 2-(alk-1-enyl)-1,3-oxathiolanes yielding 2,3,5,6-tetrahydro-1,4-oxathiocines formed through the [2,3]-sigmatropic rearrangement of the intermediate sulfonium ylides.

Thiazomycin is a novel thiazolyl peptide closely related to nocathiacin I. It was isolated from Amycolatopsis fastidiosa by chemical and biological screening. Thiazomycin showed highly potent bactericidal activity against Gram-positive pathogens (MIC range 0.002 approximately 0.064 microg/ml) and did not show cross-resistance to clinically relevant antibiotic classes such as beta-lactams, vancomycin, oxazolidinone and quinolones. It was highly efficacious against Staphylococcus aureus infection in mice exhibiting an ED(99) value of 0.15 mg/kg by subcutaneous administration. It inhibited bacterial growth by selective inhibition of protein synthesis and it was thought to interact with L11 protein and 23S rRNA of the 50S ribosome. Structurally, it possesses an oxazolidine ring in the amino-sugar residue that provides further opportunities for selective chemical modifications that are not feasible with other thiazolyl peptides. More importantly such a modification can potentially lead to semi-synthetic compounds that overcome problems that have hampered clinical development of this class of compounds. Despite its positive attributes, emergence of an unacceptable frequency of resistance poses significant challenges for further development of thiazomycin and this class of molecules for therapeutic use.

To answer the question of whether the conformation of the Leu-Pro bond is cis or trans in Ac-pTyr-Leu-Pro-Gln-Thr-Val-NH2 when complexed with the SH2 domain of Stat3, we substituted 2,2-dimethyloxazolidines derived from serine (Ser(ΨMe,Mepro)) and threonine (Thr(ΨMe,Mepro)) for proline. The 2,2-dimethyloxazolidine and 2,2-dimethylthiazolidine pseudoproline (ΨPro) analogs induce predominantly cis Xxx-ΨPro peptide bonds. As these ΨPro analogs are acid-labile, the phosphopeptides were synthesized using Fmoc-based SPPS using unprotected phosphotyrosine and 4-hydroxybenzoate as the linker that allowed release from the support by alkaline ammonolysis, conditions that kept the oxazolidine rings intact. Incorporation of Ser(ΨMe,Mepro) resulted in 69% cis Leu-ΨPro bond content in aqueous solution whereas that for Thr(ΨMe,Mepro) analog was 63%. Affinities for Stat3 were 3–5 fold lower than the lead compound and were inversely correlated with cis content. Thus we conclude that the Leu-Pro peptide bond is trans when the peptide is bound to Stat3.

A reliable method for solid-phase synthesis of peptide aldehydes by using a new oxazolidine linker is described. Based on a comparative study using the usual cleavage protocol as is used for the Fmoc-based peptide synthesis, we found that this new linker is more appropriate for the synthesis of peptide aldehydes compared with the precedent acetal, semicarbazone or threonine linker. Whereas N-Acylated oxazolidines might be partially deprotected to non-N-acylated intermediates in the TFA cocktail containing several soft nucleophiles which cause significant side reactions, the new oxazolidine linker could produce the desired peptide aldehydes by simple Et2O washing and subsequent aqueous workup in high chemical yields and purity. We demonstrate the new method is useful especially for the preparation of highly functionalized long-chain peptide aldehydes which require several scavenger chemicals in the final deprotection step.

Condensation of ephedrine with benzaldehyde, an acid catalyzed reversible reaction, producing 3,4-dimethyl-2,5-diphenyl-1,3-oxazolidine, was studied. If the starting reaction mixture contained acetic acid, it quantitatively reacted with ephedrine and produced a salt functioning as an acid catalyst. On the contrary, ephedrine hydrochloride had no catalytic effect.

In view of the synthetic and biological interest of pseudoproline (ΨR,RPro)-containing peptides, we have investigated a new strategy to these target compounds, taking into account the existence of the well-known ring–chain tautomerism occurring in the NH-free pseudoproline unit. Indeed, the NH-free oxaprolines derived from β-hyroxyamino acid (Ser, Thr) are rarely isolable in contrast to the cysteine-derived thiaproline. The strategy developed herein is based on the use of 2:3 adducts (amino acid–formaldehyde) resulting from the condensation of amino acids (Ser, Thr, Cys) with paraformaldehyde. The latter may exist as an equilibrium mixture of 1,4-diaza-3,9-dioxabicyclo[4.4.1]undecane (2) and isomeric N,N-methylenebis (oxazolidine) or -(thiazolidine) (3). Coupling these 2:3 adducts with a C-activated amino acid using conventional procedure afforded C2-unsubstituted pseudoproline (ΨH,HPro)-containing dipeptides. This strategy was applied to both oxa- and thiaprolines. Such result clearly established the usefulness of these 2:3 adducts in peptide synthesis as they allow to trap the non isolable NH-free oxaprolines. The isomerization process 2\(\leftrightarrows\)3 appeared to play a major role in this procedure, as illustrated by the peculiar case of the serine-derived 2:3 adduct 2a where no coupling occurred.

The crystal and molecular structure of (±)-2S-2-(2-chlorophenyl)-3-acetyl-1,3-oxazolidine was determined by X-ray diffraction analysis. Orthorhombic crystal with unit cell parameters a = 6.7419(8) A, b = 10.3797(12) A, c = 14.9233(18) A; space group P212121, Z = 4, ρ calc = 1.436 g/cm3, composition C11H12ClNO2. The deviation of the chlorine atom from the mean square plane of the phenyl cycle is −0.010(5) A. The five-membered oxazolidine cycle has an envelope conformation, which is typical for this class of compounds; the cycle is rotated at the C-C bond with respect to the phenyl fragment (the dihedral angle is 79.7(1)°). The spatial structure of the C2 chiral center lying in the plane of the 2-chlorophenyl fragment may be described as a distorted tetrahedron with an S configuration of the sp 3 hybridized carbon atom. Analysis of torsion angles and deviation of the nitrogen atom from the surrounding three-angle plane by −0.017(3) A allows one to speak about a tendency toward a pyramidal structure for the trisubstituted nitrogen atom. The 3D crystal structure is formed by intermolecular hydrogen bonds of C-H...O type and a strong intermolecular contact of 3.164(3) A between the chlorine atom and the carbonyl oxygen of the acyl group.

Reactions of 2-alkoxypropenals with 2-aminoalkanols afforded tautomeric mixtures of previously unknown 2-(1-alkoxyvinyl)oxazolidines and imino alcohols. The condensation takes 2 h at room temperature (89-100%) or 1-5 min under microwave irradiation. The tautomeric equilibrium shifts toward the open-chain structure with increase in the solvent polarity (CDCl3, CD2OD, DMSO-d6, D2O) and temperature. The presence of substituents in the oxazolidine ring raises the stability of the cyclic tautomer.

The chemistry of polyurethanes, polyureas, polyurethane dispersions and their reaction partners such as oxazolidines continues to grow judging by the number of patent applications and papers published. The application areas of these products also continues to increase. This paper presents a review of past and current technology including examples of the synthesis of the above species. Hybridisation of these systems is in vogue and this trend will continue. Some chemical synthesis pathways are suggested for the modification of the above-mentioned species to enhance properties. A few predictions are made as to what the future might hold. Fast and slow reacting systems are discussed along with their uses in coating structural steelwork, floors and other substrates.

The biological activity of 11 alkaloids isolated from Aconitum coreanum was studied. The compounds exhibit myorelaxant activity. Isoatisine and coryphine, which contain oxazolidine rings, are the most active. N-Oxides of 2-isobutyryl-14-hydroxyhetisine and 2-isobutyryl-13-acetyl-14-hydroxyhetisine are least active.

The reactions of methoxycarbonylcarbene, which was generated by catalytic thermal decomposition of methyl diazoacetate, with 3-ethyl-2-phenyl- or 2,3-diphenyloxazolidines resulted in the insertion of the former predominantly at the C—N bond of the oxazolidine ring to produce substituted esters of morpholine-3-carboxylic acid.

Incozol LV is a low viscosity bisoxazolidine reactive diluent that is activated by moisture present in both the polyurethane coating components (polyol and solvent) and in the atmosphere during application. The moisture triggered ring opening allows Incozol LV, by chemical reaction with polyisocyanate, to be successfully incorporated into the polyurethane coating. Incozol LV offers the benefit of reducing the VOC content of polyurethane coatings to below the present legislative demands without adversely altering the cure and coating properties.

A new oxazolidine derivative was synthesized as a reagent for individual and simultaneous determinations of Cu(II) and Pd(II) using zero- and first-order derivative spectrophotometry. 5-Imino-3-(p-methoxyphenyl)-2-methyloxazolidin-4-thione (PMOX) formed colored complexes with these metal ions in aqueous and micellar media containing cetylpyridinium bromide. The first-derivative spectra of these complexes permitted a simultaneous determination of Cu(II) and Pd(II) in concentration intervals 0.27 - 2.35 and 0.43 - 4.26 μg ml-1 at zero-crossing wavelengths of 412 and 376 nm, respectively. The influence of the experimental conditions, the ionization constant of the reagent and the stoichiometry of the complexes are reported. The methods were free from any interference of a large number of other metal ions. A critical evaluation of the proposed methods was performed by a statistical analysis of the experimental data. The methods have been applied to determine copper in steel, aluminum-, and nickel-base alloys and to the determination of palladium in activated charcoal.

We have synthesized and characterized by IR, UY,1H, and13C NMR spectroscopy new spiropyrans based on 2-thioxo-3 phenyl-5,5-dimethyl-1,3-oxazolidine. We have studied their photochromic properties in 2 propanol at -80°C. In the electronic spectra of photo-induced farms, we have detected two long-wavelength absorption bands in the 370–438 and 480–677 nm region.

The new diterpene alkaloid septedine has been isolated from the roots of Aconitum septentrionale Koelle. On the basis of spectral characteristics and x-ray structural analysis (diffractometer, CuKα radiation, 1537 reflections, direct method, R = 0.055) it has been established that septedine has an atisine skeleton including an oxazolidine ring with a C14–C20 bridge.

We have studied hydrazinolysis of (4S,5S)-3-benzyl-4-hydroxymethyl-5-(4-nitrophenyl)oxazolidine, (1R,4S,5S)-1-(4-nitrophenyl)-1-aza-3,7-dioxabicyclo[3,3,0]octane, and (1R,4S,5S)-1-benzyl-4-(4-nitrophenyl)-1-azonia-3,7-dioxabicyclo[3,3,0]octane. We have shown that neutral compounds are decomposed with opening of the oxazolidine ring, while quaternary ammonium salts react with hydrazine in several directions.

Phenylephrine oxazolidine is a new prodrug of phenylephrine developed for improving ocular absorption and reducing systemic side effects. In the present study, high- and low-melting phenylephrine oxazolidines (HMP and LMP) were characterized in terms of their stereochemistry and crystal properties. It was found that the molecular configuration of the prodrug in the crystals of either HMP or LMP is identical (5R/2R). The two crystals were shown to have the same IR spectra and X-ray diffraction patterns but different crystal habits, thermal properties, solubilities and intrinsic dissolution rates. Single crystal X-ray structure analysis indicates that crystals of both HMP and LMP are orthorhombic and belong to the P212121 space group with four molecules in a unit cell (a = 20.697 A, b = 7.065 A, and c = 9.304 A). The molecules in the crystal are held together by an intermolecular hydrogen bonding interaction between N(3) and O(13). The different physical properties observed for LMP result from crystal imperfections caused by the presence of trace amounts (often at levels

The condensation of α-hydroxyaminoalcohols with aldehydes and acetone gave 3-hydroxyoxazolidines and tautomeric N-(2-hydroxyethyl)-α-arylnitrones, whose oxidation by PbO2 in methanol leads to stable oxazolidine nitroxyl radicals with methoxy groups at C2 and C4.

1,3-Oxazolidines are highly interesting because of their unique properties that allow them to be used in medicine and industry. They are also scientifically interesting as products of enantioselective synthesis of planar-chiral compounds [1–3]. We established previously the absolute configurations of the chiral centers of several 1,3-oxazolidines prepared from dand l-ephedrines [4]. The various configurations of the chiral center in dand l-ephedrines should produce various conformations of the oxazolidine ring of 2. According to several researchers [5–8], the reaction of -aminoalcohols with various aldehydes occurs usually stereoselectively or with formation of the S-stereoisomer or the R-epimer. The stereoselectivity depends usually on the nature of the reactants and solvents. Herein we present results from a study of the reaction of d-threo-2-methylamino-1-phenyl-1-propanol (the alkaloid d-pseudoephedrine) (1) with previously unstudied 4-morpholinylbenzaldehyde, which formed 2 according to the following scheme

Mannich reaction of bis(nitroxymethyl)oxazolidine (I) is found to furnish quaternary ammonium salt (IV) with unique structure instead of the expected Mannich bases.

The compounds 2-(ethoxycarbonylmethyl)-δ2-l,3-oxazoline and 1-methyl-2-(methoxycarbonylmethylene)-1,3-oxazolidine are hydrochlorinated at the C=N or C= C bond, respectively, with subsequent opening of the oxazolidine ring. Depending on the reaction conditions, this occurs regioselectively to form various products.

PMR spectra of 2-aryl- and 2-hetaryloxazolidines-1,3 are studied. A PMR criterion is revealed according to which the absolute configuration of the C(2) atom of the oxazolidine ring can be assigned.

Hydrogenolysis of 3-benzyloxycarbonyloxazolidine-5-one and 3-benzyloxycarbonyl-4-benzyloxazolidine-5-one by Et3SiH in the presence of F3.CCO2H is demonstrated to be a convenient method for preparing substituted N-methylaminoacids. In contrast with catalytic hydrogenation on Pd/C catalyst, the benzyloxycarbonyl is not removed and the methyl is not lost using this method.

It was established that 2-alkoxycarbonylntethylene derivatives of oxazolidine and imidazolidine react readily with 4-nitrobenzonitrile N-oxide; the reaction takes place at the methylidyne carbon atom to give intermediate oximes, which can then undergo cyclization to isoxazoles. Their tautomers —benzimidazole and δ2-oxazoline derivatives —react with considerably greater difficulty; in the first case the reaction takes place at a different center, viz., the ring nitrogen atom.

Heating cyclohexanespiro-2-oxazolidine at 160–200°C in the presence of protic acids results in its decomposition to giveN-(2-hydroxyethyl)cyclohexylamine,N-(2-hydroxyethyl)-4,5,6,7-tetrahydroindole, and 2-cyclohexylidenecyclohexanone. The possible pathways leading to these compounds are discussed.

Condensation of monoethanolamine with formaldehyde affords 1,6-diaza-3,8-dioxabicyclo[4.4.1]undecane andN,N′-methylene-bis(oxazolidine) in a ratio of 1∶8.

We are the first to show that l,l-methylenebis(3-methylimidazolidine) (I), similar to its oxazolidine analog [i], is cleaved at the exocyclic N-C bond by the action of CINO, while !,l-methyienebis(3-methyiperhydro-l,3-diazine) (IV) is cleaved at the endocyclic N-C bond, in contrast to its perhydro-l,3-oxazine analog [i]. The formation of (V) is a consequence of the consecutive hydrolysis due traces of moisture and deamination. This was confirmed by convergent synthesis from (VI).

Condensation reactions of copper(II) complexes of DL a n d L forms of alanine, serine and threonine with aliphatic aldehydes show differential reactivity patterns. The reaction of Cu(DL-Ala)2 with formaldehyde and ammonia at pH 5 yields pentamethylene diaza group containing product (_1) but at pH > 8"0 yields oxazolidine group containing product (_2). However, reaction of Cu(L-AIa)2 with formaldehyde and ammonia at pH 8.5 yields an optically active isomer of 1. Similarly copper(II) complexes of DL-serine and DL-threonine readily undergo condensation reaction with aldehydes such as formaldehyde, acetaldehyde, propionaldehyde etc. yielding oxazolidine group containing products whereas the corresponding L-amino acidato copper(II) complexes do not undergo condensation reactions under the same experimental conditions. These aspects are discussed.

New spirans of the 5,5-dimethyl-3-phenyl-2-oxazolidone series that display photo-chromic properties in alcohol solutions at -80 °C were synthesized. The photoinduced forms are characterized by the presence of two long-wave absorption bands at 350–420 nm and 500–650 nm. The 1H and 13C NMR spectra were studied. Anisochronicity of the diastereotopic methyl groups of the oxazolidone ring shows up only in the 13C NMR spectra.

The behavior of 5-alkyl-1,4-diaza and 5-alkyl-1-aza-4-oxabicyclo[3.3.0]octan-8-ones has been studied towards catalytic reduction, reduction by lithium aluminum hydride, acylation, cyanoethylation, alkylation, etc. The oxazolidine ring in 5-alkyl-1-aza-4-oxabicyclo[3.3.0]octan-8-ones was readily opened by electrophilic and nucleophilic reagents whereas most of the reactions of 5-alkyl-1,4-diazabi-cyclo[3.3.0]octan-8-ones occurred with retention of the bicyclic structure.

2-Phenylindan-1,3-dione reacts with aryl isocyanates in benzene in the presence of catalytic amounts of triethylamine with the formation of 3-aryl -3a-phenylindano-[2,1-d]oxazolidine-2,4-diones. In pyridine, this reaction leads to 2-arylcarbamoyl-2-phenylindan-1,3-dione.

dl-cis- and dl-trans-6-(4-Carboxybutyl)-2-oxo-cis-hexahydrothieno[3,4-d]oxazoles were synthesized by the action of phosgene on r-4-amino-c-3-hydroxy-c(or, respectively, †)-2-(4-carboxybutyl)thiophan hydrohalides. It is shown that the acid hydrolysis of r-4-benzamido-t-3-hydroxy-c(or t)-2-(4-methoxycarbonylbutyl)thiophans is accompanied by inversion to give r-4-amino-c-3-hydroxy-c(or t)-2-(4-alkoxycarbonylbutyl)thiophans.

21-Hydroxy(acetoxy)-2′,2′-dimethyl-[17α, 16α-d]-oxazolidines of 20-ketosteroids can be synthesized by two methods. One of these is based on the ammonolysis of 16α,17α-epoxypregn-5-en-3Β,21-diol-20-one 20-carbethoxyhydrazone and can have preparative value.