4‐Ethynyl‐4‐hydroxycyclohexan‐1‐one and 4‐ethynyl‐4‐hydroxy‐2,3,5,6‐tetramethylcyclohexa‐2,5‐dien‐1‐one

The title compounds, C₈H₁₀O₂, (I), and C₁₂H₁₄O₂, (II), occurred as by‐products in the controlled synthesis of a series of bis­(gem‐alkynols), prepared as part of an extensive study of synthon formation in simple gem‐alkynol derivatives. The two 4‐(gem‐alkynol)‐1‐ones crystallize in space group P2₁/c, (I) with Z′ = 1 and (II) with Z′ = 2. Both structures are dominated by O—H?O=C hydrogen bonds, which form simple chains in the cyclo­hexane derivative, (I), and centrosymmetric dimers, of both symmetry‐independent mol­ecules, in the cyclo­hexa‐2,5‐diene, (II). These strong synthons are further stabilized by C[triple‐bond]C—H?O=C, C_methylene—H?O(H) and C_methyl—H?O(H) interactions. The direct intermolecular interactions between donors and acceptors in the gem‐alkynol group, which characterize the bis­(gem‐alkynol) analogues of (I) and (II), are not present in the ketone derivatives studied here.     

Stereochemistry of 1,3‐dipolar‐cycloaddition of 3,4‐dihydroisoquinoline‐ and 3,4‐dihydro‐carboline‐N‐methoxycarbonyl‐ and N‐phenacyl‐methylides with maleic and fumaric nitrile

The 1,3‐dipolar‐cycloadditions of two kind of isoquinolinium and carbolinium ylides with fumaric and maleic nitrile resulted in pyrroloisoquinoline and indolizino[8,7‐b]indole derivatives, respectively, which are analogues of biologically active alkaloids. The cycloadditions were performed in good yield and proved to be stereoselective. The structure elucidation and complete ¹H and ¹³C assignments have been achieved by a combination of various one‐ and two‐dimensional NMR experiments.     

N‐Amidino‐4‐hydroxy‐l‐proline monohydrate and N‐amidino‐l‐methionine monohydrate

The title amidino‐amino acids (a‐Hpro), C₆H₁₁N₃O₃·H₂O, (I), and a‐Met, C₆H₁₃N₃O₂S·H₂O, (II), respectively, exist in the form of zwitterions. The five‐membered pyrrolidine ring in (I) adopts an envelope conformation, with the Cγ atom out of the plane defined by the rest of the ring atoms, and with the hydroxyl and carboxyl­ate groups in a trans configuration relative to the ring plane. The two crystallographically independent zwitterions in (II) reveal quite different conformations of their side chains and a slightly different orientation of the guanidine moiety with respect to the carboxyl­ate group. The crystal structures of both (I) and (II) are stabilized by extensive networks of O—H·O, N—H·O and C—H·O hydrogen bonds, the network being three‐dimensional in (I) and two‐dimensional in (II).     

5‐Acetyl‐2‐amino‐6‐methyl‐4‐phenyl‐4H‐pyran‐3‐carbonitrile and 2‐amino‐5‐benzoyl‐6‐methyl‐4‐phenyl‐4H‐pyran‐3‐carbonitrile acetonitrile solvate

The syntheses, X‐ray structural investigations and calculations of the conformational preferences of the carbonyl substituent with respect to the pyran ring have been carried out for the two title compounds, viz. C₁₅H₁₄N₂O₂, (II), and C₂₀H₁₆N₂O₂·C₂H₃N, (III), respectively. In both mol­ecules, the heterocyclic ring adopts a flattened boat conformation. In (II), the carbonyl group and a double bond of the heterocyclic ring are syn, but in (III) they are anti. The carbonyl group forms a short contact with a methyl group H atom in (II). The dihedral angles between the pseudo‐axial phenyl substituent and the flat part of the pyran ring are 92.7 (1) and 93.2 (1)° in (II) and (III), respectively. In the crystal structure of (II), inter­molecular N—H⋯N and N—H⋯O hydrogen bonds link the mol­ecules into a sheet along the (103) plane, while in (III), they link the mol­ecules into ribbons along the a axis.     

rac‐5‐Diphenylacetyl‐2,2,4‐trimethyl‐2,3,4,5‐tetrahydro‐1,5‐benzothiazepine and rac‐5‐formyl‐2,2,4‐trimethyl‐2,3,4,5‐tetrahydro‐1,5‐benzothiazepine

rac‐5‐Diphenylacetyl‐2,2,4‐trimethyl‐2,3,4,5‐tetrahydro‐1,5‐benzothiazepine, C₂₆H₂₇NOS, (I), and rac‐5‐formyl‐2,2,4‐trimethyl‐2,3,4,5‐tetrahydro‐1,5‐benzothiazepine, C₁₃H₁₇NOS, (II), are both characterized by a planar configuration around the heterocyclic N atom. In contrast with the chair conformation of the parent benzothiazepine, which has no substituents at the heterocyclic N atom, the seven‐membered ring adopts a boat conformation in (I) and a conformation intermediate between boat and twist‐boat in (II). The molecules lack a symmetry plane, indicating distortions from the perfect boat or twist‐boat conformations. The supramolecular architectures are significantly different, depending in (I) on C—H...O interactions and intermolecular S...S contacts, and in (II) on a single aromatic π–π stacking interaction.     

Synthesis and Herbicidal Activity of Novel 4‐Acyl‐2,5‐disubstituted‐3‐hydroxypyrazoles and 4‐Arylcarbonyl‐3‐substitutedisoxazol‐5‐ones

Two series of novel 4‐acyl‐2,5‐disubstituted‐3‐hydroxypyrazoles 3a , 3b , 3c , 3d , 3e , 3f , 3g , 3h and 4‐arylcarbonyl‐3‐substitutedisoxazol‐5‐ones 7a , 7b , 7c , 7d , 7e , 7f , 7g , 7h , 7i were synthesized by the Scotton–Baumann reaction of 2,5‐disubstituted‐2,4‐dihydro‐pyrazol‐3‐ones 1 or 3‐substituted‐4H‐isoxazol‐5‐ones 6 and various acyl chlorides, followed by the Fries rearrangement in the presence of calcium hydroxide and calcium oxide as the catalyst. Their structures were confirmed by IR, ¹H NMR, mass spectroscopy, and elemental analyses. ¹H NMR indicated that compounds 3 existed in enol forms and compounds 7 in keto configurations. The results of preliminary bioassays showed that some of the title compounds 3 and 7 exhibited moderate to good herbicidal activities against Brassica campestris L. at the concentration of 100 mg/L. Isoxazole compounds 7 showed better herbicidal activity against B. campestris L. than pyrazole compounds 3 did at the concentration of 100 mg/L. Moreover, most of the isoxazole compounds displayed higher herbicidal activity against B. campestris L. than Echinochloa crus‐galli. However, these compounds showed weak herbicidal activities at the concentration of 10 mg/L.     

Syntheses and Fluorescent Properties of 6‐Methoxy‐2‐oxoquinoline‐3,4‐dicarbonitriles and 6,7‐Dimethoxy‐2‐oxoquinoline‐3,4‐dicarbonitriles

4‐Chlorocarbostyrils 3 , 12 , 17 , 24 , 26 with methoxy substituents in 6, 7, or 6,7‐position react with potassium cyanide in a p‐toluenesulfinate mediated reaction either to the highly fluorescent and stable 2‐oxoquinoline‐3,4‐dicarbonitriles 6 , 27 , 29 , 30 or at slightly lower temperatures to 4‐monocarbonitriles 5 , 13 , 18 . 4‐Chlorocarbostyril 3 and lithium p‐toluenesulfinate gave pure 4‐toluenesulfonylquinolone 4 , which reacted with potassium cyanide either to monocarbonitrile 5 or dicarbonitrile 6 , depending on the reaction conditions. 4‐Trifluoromethylquinolones 9 and 19 were prepared for fluorescence comparison from the appropriate methoxyaniline and 4,4,4‐trifluoroacetoacetate. The fluorescence properties such as emission wavelengths and quantum yields of 6‐methoxyderivatives 4 , 5 , 6 , 9 , 13 were studied and compared with those of 7‐methoxy derivatives 18 , 19 and 6,7‐dimethoxyderivatives 27 , 28 , 29 , 30 . 6,7‐Dimethoxy derivatives show best results, showing long‐waved fluorescence spectra up to 520 nm and acceptable quantum yields up to 0.46 for 3,4‐dicyano derivative 27 excited at 440 nm in acetonitrile.     

Synthesis of 15‐Cyano‐12‐oxopentadecano‐15‐lactone and 15‐Cyano‐ 12‐oxopentadecano‐15‐lactam

15‐Cyano‐12‐oxopentadecano‐15‐lactone was synthesized in 59% total yield starting from 2‐nitrocyclododecanone by Michael addition to acrylaldehyde, followed by reaction with trimethylsilylcyanide, hydrolysis, ring‐expansion, and Nef reaction. A two‐step, one‐pot synthesis of intermediate 2‐hydroxy‐4‐(1‐nitro‐2‐oxycyclododecyl)butanenitrile from 3‐(1‐nitro‐2‐oxocyclododecyl)propanal was developed and the conditions for the Nef reaction were studied. 15‐Cyano‐12‐oxopentadecano‐15‐lactam was synthesized in 40% total yield starting from 2‐nitrocyclododecanone by Michael addition to acrylaldehyde, followed by Strecker reaction, ring‐expansion, and Nef reaction. The conditions for the Strecker and Nef reactions were studied. The structures of the target compounds, intermediates, and by‐product were characterized by IR, ¹H‐ and ¹³C‐NMR, and elemental analysis or MS.     

1H and 13C NMR analysis of 2‐acetamido‐3‐mercapto‐3‐methyl‐N‐aryl‐butanamides and 2‐acetamido‐3‐methyl‐3‐nitrososulfanyl‐N‐aryl‐butanamide derivatives

The complete assignment of the ¹H and ¹³C NMR spectra of various 2‐acetamido‐3‐mercapto‐3‐methyl‐N‐aryl‐butanamides and 2‐acetamide‐3‐methyl‐3‐nitrososulfanyl‐N‐aryl‐butanamides with p‐methoxy, o‐chloro and m‐chloro substituents is reported. Copyright © 2013 John Wiley & Sons, Ltd.     

Synthesis and characterization of poly(DTC‐b‐PEG‐b‐DTC) triblock and poly(TMC‐b‐DTC‐b‐PEG‐b‐DTC‐b‐TMC) pentablock copolymers and kinetics of the polymerization

Dihydroxyl capped biodegradable poly(DTC‐b‐PEG‐b‐DTC) (BCB) triblock copolymer and poly(TMC‐b‐DTC‐b‐PEG‐b‐DTC‐b‐TMC) (ABCBA) pentablock copolymer have been synthesized by PEG and BCB copolymer as macroinitiator in the presence of yttrium tris(2,6‐di‐tert‐butyl‐4‐methylphenolate). The copolymers without random segments have been thoroughly characterized by ¹H, ¹³C‐NMR, SEC, and DSC. Molecular weights of the obtained copolymers are dependent on the amount of PEGs and coincide with the theoretical values. The exchange reaction of yttrium alkoxide and hydroxyl end group is essential for controlling the products' molecular weight. Their thermal behaviors are relevant to the chain lengths of PEG and PDTC segments. The Monte Carlo method has been developed to estimate the chain propagation constant and exchange reaction constant. In average, one exchange reaction will occur after approximately six monomer molecules insert into the growing chain. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1787–1796, 2005     

1‐Acetyl‐3‐ferrocenyl‐5‐methyl‐1H‐pyrazole and 1‐acetyl‐5‐ferrocenyl‐3‐(2‐pyrid­yl)‐1H‐pyrazole

Mol­ecules of 1‐acetyl‐3‐ferrocenyl‐5‐methyl‐1H‐pyrazole, [Fe(C₅H₅)(C₁₁H₁₁N₂O)], form a centrosymmetric dimer generated by a combination of one C—H⋯π(pyrazole) and one C—H⋯π(cyclo­penta­dienyl) inter­action. The dimers are linked by C—H⋯π inter­actions, involving the pyrazole rings as acceptors, into layers parallel to (10). Mol­ecules of 1‐acetyl‐5‐ferrocenyl‐3‐(2‐pyrid­yl)‐1H‐pyrazole, [Fe(C₅H₅)(C₁₅H₁₂N₃O)], are linked by C—H⋯O inter­actions into a chain running in the [010] direction. Two chains of this type passing through each unit cell are connected by O⋯π(pyridyl) inter­actions into an [010] double chain.     

Ammonium N‐acetyl‐l‐threoninate and methyl­ammonium N‐acetyl‐l‐threoninate

Ammonium N‐acetyl‐l ‐threoninate, NH₄⁺·C₆H₁₀NO₄^?, and methyl­ammonium N‐acetyl‐l ‐threoninate, CH₆N⁺·­C₆H₁₀NO₄^?, crystallize in the orthorhombic P2₁2₁2₁ and monoclinic P2₁ space groups, respectively. The two crystals present the same packing features consisting of infinite ribbons of screw‐related N‐acetyl‐l ‐threoninate anions linked together through pairs of hydrogen bonds. The cations interconnect neighbouring ribbons of anions involving all the nitrogen‐H atoms in three‐dimensional networks of hydrogen bonds. The hydrogen‐bond patterns include asymmetric `three‐centred' systems. In both structures, the Thr side chain is in the favoured (g^?g⁺) conformation.     

Ultrasound‐Assisted Facile Synthesis and Antimicrobial Studies of Alkanediyl‐bis‐thiazolidin‐4‐ones and Alkanediyl‐bis‐thiazinan‐4‐ones

Alkanediyl‐bis‐2‐aryl‐thiazolidin‐4‐one and alkanediyl‐bis‐2‐aryl‐1,3‐thiazinan‐4‐one derivatives have been congregated in a single step reaction of diaminoalkanes, aryl aldehydes, and sulfanyl acids in the presence of coupling agent N,N′‐dicyclohexylcarbodiimide under ultrasonic conditions. This method of constructing 4‐keto derivatives of thiazolidine and thiazinane is quick and clean besides yielding the products in quantitative yields. The spectral techniques corroborated the structures of the isolated products. Biological assay of the synthesized products has also been reported.     

l‐Isoleucyl‐l‐serine 0.33‐hydrate,l‐phenyl­alanyl‐l‐serine and l‐methionyl‐l‐serine 0.34‐hydrate

The structures of the title dipeptides, C₉H₁₈N₂O₄·0.33H₂O, C₁₂H₁₆N₂O₄ and C₈H₁₆N₂O₄S·0.34H₂O, complete a series of investigations focused on l ‐Xaa‐l ‐serine peptides, where Xaa is a hydro­phobic residue. All three structures are divided into hydro­philic and hydro­phobic layers. The hydro­philic layers are thin for l ‐phenyl­alanyl‐l ‐serine, rendered possible by an unusual peptide conformation, and thick for l ‐isoleucyl‐l ‐serine and l ‐methionyl‐l ‐serine, which include cocrystallized water mol­ecules on the twofold axes.     

5‐Acetyl‐2‐amino‐6‐methyl‐4‐(3‐nitrophenyl)‐4H‐pyran‐3‐carbonitrile and 2‐amino‐5‐ethoxycarbonyl‐6‐methyl‐4‐(3‐nitrophenyl)‐4H‐pyrano‐3‐carbonitrile

The structures of the title compounds, C₁₅H₁₃N₃O₄, (I), and C₁₆H₁₅N₃O₅ [IUPAC name: ethyl 6‐amino‐5‐cyano‐2‐methyl‐4‐(3‐nitro­phenyl)‐4H‐pyrano‐3‐carboxyl­ate], (II), are very similar, with the heterocyclic rings adopting boat conformations. The pseudo‐axial m‐nitro­phenyl substituents are rotated by 84.0 (1) and 98.7 (1)° in (I) and (II), respectively, with respect to the four coplanar atoms of the boat. The dihedral angles between the phenyl rings and nitro groups are 12.1 (2) and 8.4 (2)° in (I) and (II), respectively. The two compounds have similar patterns of intermolecular N—H?O and N—H?N hydrogen bonding, which link mol­ecules into infinite tapes along b .     

O‐Benzyl‐N‐tert‐butoxy­carbonyl‐N‐methyl‐l‐tyrosine

The crystal structure of the title compound, alternatively called 3‐[4‐(benzyl­oxy)­phenyl]‐2‐(N‐tert‐butoxy­car­bonyl‐N‐methyl­amino)­propi­onic acid, C₂₂H₂₇NO₅, has been studied in order to ex­amine the role of N‐methyl­ation as a determinant of peptide conformation. The conformation of the tert‐butoxy­carbonyl group is trans–trans. The side chain has a folded conformation and the two phenyl rings are effectively perpendicular to one another. The carboxyl­ate hydroxyl group and the urethane carbonyl group form a strong intermolecular O—H?O hydrogen bond.     

A simple synthesis of 5‐ethoxycarbonyl‐6‐phenyl‐1,3‐dioxin‐4‐ones and ethyl 3‐benzoyl‐4‐oxo‐2,6‐diphenylpyran‐5‐carboxylate

4‐Ethoxycarbonyl‐5‐phenyl‐2,3‐dihydrofuran‐2,3‐dione 1 reacts with aldehydes via the acylketene intermediate 2 giving the 1,3‐dioxin‐4‐ones 3a‐e and the 1,4‐bis(5‐ethoxycarbonyl‐4‐oxo‐6‐phenyl‐4H‐1,3‐dioxin‐2‐yl)benzene 4 , and a one step reaction between dibenzoylmethane and oxalylchloride gave 3,5‐dibenzoyl‐2,6‐diphenyl‐4‐pyrone 7 . The reaction of 1 with dibenzoylmethane, a dicarbonyl compound, provided ethyl 3‐benzoyl‐4‐oxo‐2,6‐diphenylpyran‐5‐carboxylate derivative 9 . Compound 9 was converted into the corresponding ethyl 3‐benzoyl‐4‐hydroxy‐2,6‐diphenylpyridine‐5‐carboxylate derivative 10 via its reaction with ammonium hydroxyde solution in 1 ‐butanol.