Synthesis and Infrared Absorption Spectra of 5′-methyl-2′-hydroxychalcones: I. 5′-methyl-2′-hydroxychalcone and its 4-Substituted Derivatives

Seven 2′-hydroxychalcone derivatives with a methyl group on the 5′-position were synthesized. Infrared absorption spectra of these new compounds are discussed.     

Effect of tin tetrachloride on thermal decompositions of α,α′-azobisisobutyronitrile and dimethyl α,α′-azobisisobutyrate

Thermal decomposition of α,α′-azobisisobutyronitrile (AIBN) and dimethyl α,α′-azobisisobutyrate (MAIB) in the presence of a large amount of tin tetrachloride was investigated to determine the effect of complex formation on the decomposition rates and yields of the recombination products. The addition of tin tetrachloride significantly increased the decomposition rates; the observed first-order rate constant increased by factors of 4.5 and 17 at molar ratios of [SnCl₄]/[AIBN] = 21.65 and [SnCl₄]/[MAIB] = 19.53, respectively. It was found that the decomposition of these azo compounds was also accelerated by the addition of a comparable amount of donor solvent such as ethyl acetate or propionitrile to tin tetrachloride and that the enhancement in rate was accounted for by a larger frequency factor in the Arrhenius equation. Furthermore, the addition of tin tetrachloride seemed to suppress the formation of recombination products, tetramethyl succinonitrile and dimethyl tetramethylsuccinate, of the radicals produced by decomposition.     

Mass spectra of some α-substituted phenyl-α,α′-dimethoxyl ketones and their derivatives

The mass spectra of some α-substituted phenyl-α,α′-dimethoxyl ketones (compounds 1) and their 2,4-dinitrophenylhydrazones (compounds 2) and semicarbazones (compounds 3) have been studied. The characteristic fragments at m/z (M ? 73) from compounds 1, m/z (M ? 253) from compounds 2 and m/z (M ? 130) from compounds 3 are abundant and proposed to be [ArCROCH₃]⁺. Fragmentations yielding [M⁺ ? 49] from compounds 2 are abnormal and probably involve the methoxyl and nitro groups. The intense peak at m/z 130 due to [CH₃OCH₂CNNHCONH₂]⁺ from compounds 3 corresponds to α-cleavage of the molecular ion. Some other fragments from these new compounds are interpreted in this paper.     

α-Melanotropin Labelled at its Tyrosine2 Residue: Synthesis and Biological Activities of 3′-Iodotyrosine2-,3′-125Iodotyrosine2-,3′,5′-Diiodotyrosine2-, and (3′,5′-3H2)tyrosine2-α-Melanotropin,and of Related Peptides

α-MSH was labelled at its tyrosine² residue with tritium and iodine. Several synthetic routes were investigated by preparing 13 precursor or mode compounds and 4 different labelled products (via about 40 intermediates). Their melanotropic activity was determined with an in vitro frog skin assay and, for some of the compounds, with a tyrosinase assay. The tritiation was performed on [Tyr(I₂)²]α-MSH by catalytic halogen/tritium exchange, yielding α-MSH of high specific radioactivity (34 Ci/mmol) and full biological activity. Iodination was studied in detail using five different techniques. An equimolar chloramine T procedure proved to be the most convenient and reproducible method, resulting in monoiodinated α-MSH containing 99% of the label in position 2. The biological activity was 50% that of α-MSH; the specific radioactivity, determined in a competitive binding assay with a highly specific α-MSH antiserum and [Tyr(I)²]α-MSH as competitor, was 1530 Ci/mmol. The labelling techniques and the bioligical results are discussed.     

A convenient synthesis of α,α′‐ homo‐ and α,α′‐hetero‐bifunctionalized poly(ε‐caprolactone)s by ring opening polymerization: The potentially valuable precursors for miktoarm star copolymers

Two new ring opening polymerization (ROP) initiators, namely, (3‐allyl‐2‐(allyloxy)phenyl)methanol and (3‐allyl‐2‐(prop‐2‐yn‐1‐yloxy)phenyl)methanol each containing two reactive functionalities viz. allyl, allyloxy and allyl, propargyloxy, respectively, were synthesized from 3‐allylsalicyaldehyde as a starting material. Well defined α‐allyl, α′‐allyloxy and α‐allyl, α′‐propargyloxy bifunctionalized poly(ε‐caprolactone)s with molecular weights in the range 4200–9500 and 3600–10,900 g/mol and molecular weight distributions in the range 1.16–1.18 and 1.15–1.16, respectively, were synthesized by ROP of ε‐caprolactone employing these initiators. The presence of α‐allyl, α′‐allyloxy and α‐allyl, α′‐propargyloxy functionalities on poly(ε‐caprolactone)s was confirmed by FT‐IR, ¹H, ¹³C NMR spectroscopy, and MALDI‐TOF analysis. The kinetic study of ROP of ε‐caprolactone with both the initiators revealed the pseudo first order kinetics with respect to ε‐caprolactone consumption and controlled behavior of polymerization reactions. The usefulness of α‐allyl, α′‐allyloxy functionalities on poly(ε‐caprolactone) was demonstrated by performing the thiol‐ene reaction with poly(ethylene glycol) thiol to obtain (mPEG)₂‐PCL miktoarm star copolymer. α‐Allyl, α′‐propargyloxy functionalities on poly(ε‐caprolactone) were utilized in orthogonal reactions i.e copper catalyzed alkyne‐azide click (CuAAC) with azido functionalized poly(N‐isopropylacrylamide) followed by thiol‐ene reaction with poly(ethylene glycol) thiol to synthesize PCL‐PNIPAAm‐mPEG miktoarm star terpolymer. The preliminary characterization of A₂B and ABC miktoarm star copolymers was carried out by ¹H NMR spectroscopy and gel permeation chromatography (GPC). © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 844–860     

Synthesis of α-2′-deoxynucleosides

α-Thymidine (4) was synthesized from thymidine (1) in 3 steps in 36% overall yield without using chro-matography and with the possibility of increasing the yield to 85% by reusing the remaining α,β-mixture. 1-(2-Deoxy-3,5-di-O-p-toluoyl-α-D-erythro-pentofuranosyl)thymine (3) was further converted to 1-(2-deoxy-α-D-erythro-pentofuranosyl)-5-methylcytosine (5) .     

Synthesis and characterization of α,α'-bis(aminomethyl)oligothiophenes and their related compounds

We have synthesized and characterized a series of novel compounds of α,α'-bis(arninomethyl)oligothiophenes and their related compounds whose degree of polymerization spans two (dimer) to five (pentamer). The compounds presented in our studies are α,α'-bis[(2,2,5,5-tetramethyl-1-aza-2,5-disilacyclopenthyl)methyl]oligothiophene, α,α'-bis(aminomethyl)oligothiophene dihydrochloride and α,α'-bis(aminomethyl)oligothiophene. These compounds exhibit desired chemical activity while maintaining controllable electronic properties. The synthetic processes of the oligothiophenes are as follows: 2-aminomethylthiophene is first ‘protected’ and the thiophene rings are coupled using standard Grignard methods. The protected groups are removed at the final stage of the reaction. The compounds show unique properties; for example α,α'-bis(aminomethyl)oligothiophene dihydrochloride is soluble in water. The results of electronic spectra and titration are also presented.     

Polyesters,polycarbonate, and polyurethanes from a novel monomer: α,α,α′,α′-tetramethyl-1,4-tetrafluorobenzenedimethanol

The novel diol monomer, α,α,α′,α′-tetramethyl-1,4-tetrafluorobenzenedimethanol, has been synthesized by a convenient route which involves the addition of acetone to 1,4-dilithiotetrafluorobenzene and can be purified by washing with hexanes. It does not directly undergo condensation polymerizations with diacid chlorides. Its disodium salt, prepared by its reaction with sodium hydride, similarly fails to undergo such polymerizations readily. However, the dilithium salt, prepared in situ by the reaction of the title diol with 2 equiv of n-butyllithium in tetrahydrofuran, is suitable for the preparation of various classes of condensation polymers. Four polyesters and one polycarbonate derived from the reactions of the dilithium salt of the diol with adipoly dichloride, sebacoyl dichloride, isophthaloyl dichloride, terephthaloyl dichloride, and phosgene and two polyurethanes derived from its reactions with tolylene-2,4-diisocyanate and methylene-di-1,4-phenyl diisocyanate were prepared. Each was fully characterized by GPC, NMR, IR, and UV-visible spectroscopies, and the results of these studies are reported herein. © 1993 John Wiley & Sons, Inc.     

α,ω-Dihydroxyalkan-α,α-diphosphonsäuren durch Desaminierung von ω-Aminoalkandiphosphonsäuren

α,ω-Dihydroxyalkane-α,α-diphosphonic Acids by Desamination of ω-Aminoalkanediphosphonic Acids The title compounds represent a new group of complexing diphosphonic acids which are synthesized by desamination of ω-amino-α-hydroxyalkane-α,α-diphosphonic acids. In case of α,ω-dihydroxypropane-α,α-diphosphonic acid ( 1 ) a phosphonylated phostone is formed by dehydration. In contrast, the ω-phenyl drivative of ( 1 ) yields in a smooth reaction under the same conditions 2-hydroxy-5-phenyl-3-phosphono-1.2-oxaphosphol-3-en-2-oxide ( 6 ).     

α,β-Epoxyketon → Alkinon-Fragmentierung II: Pyrolytischer Zerfall der Hydrazone aus α,β-Epoxyketonen und N-Amino-aziridinen. Über synthetische Methoden, 4. Mitteilung

Numerous examples illustrate the course of the thermolysis of hydrazones derived from α,β-epoxyketones and 2-phenyl- or trans-2,3-diphenyl-1-amino-aziridines. This process constitutes a preparatively useful method for the fragmentation of α,β-epoxyketones to acetylenic carbonyl compounds including acetylenic aldehydes. Monohydrazones from phenylglyoxal and substituted N-amino-aziridines decompose smoothly and stereospecifically to the corresponding olefins and diazoacetophenone; such a process might also be useful for the preparation of other α-diazocarbonyl compounds.     

Destabilized carbenium ions: α-imidoyl carbenium ions and the electron impact mass spectra of α-haloaldimines and α-haloketimines

A series of α-chloro- and α-bromoketimines compounds (1-9) with different substituents at the α-position and at the imino group has been investigated by electron impact mass spectrometry as possible precursors of the correspondingly substituted α-imidoyl carbenium ion, an important class of destabilized carbenium ions. The main fragmentation of the molecular ions of compounds, 1-9 in the ion source corresponds to an α-cleavage at the imino group; however, fragment ions are also formed by loss of the α-halo substituent. These fragment ions correspond at least formally to α-imidoyl carbenium ions. Their further reactions in dependence on the type of substituents at the imino group and at the α-C atom, were studied by mass-analysed ion kinetic energy and collisional activation mass spectrometry. The results agree with the initial formation of destabilized α-imidoyl carbenium ions but indicate an easy rearrangement of these ions in the presence of suitable alkyl substituents by 1,2- and 1,4-hydrogen shifts to more stable isomers.     

5-(α-Fluorovinyl)tryptamines and 5-(α-Fluorovinyl)-3-(N-methyl-1′,2′,5′,6′,-tetrahydropyridin-3′- and -4′-yl)indoles—5-(α-Fluorovinyl)tryptamines

5-(α-Fluorovinyl)tryptamines 4a, 4b and 5-(α-fluorovinyl)-3-(N-methyl-1′,2′,5′,6′-tetrahydropyridin-3′- and -4′-yl) indoles 5a, 5b were synthesized using 5-(α-fluorovinyl)indole ( 7 ). The target compounds are bioisosteres of 5-carboxyamido substituted tryptamines and their tetrahydropyridyl analogs.     

Two New Diterpens Phenols-7α-Methoxydeoxocryptojaponol and 7β-Hydroxydeoxocryptojaponol

Six crystalline compounds, α-cedrol, β-sitosterol, cryptojaponol sugiol and two new diterpene phenols were isolated from the hexane extractive of wood of Juniperus formosana Hayata. Two new phenolic derivatives of deoxocryptojaponoi were established as 7α-methoxydeoxocryptojaponol and 7β-hydroxydeoxocryptojaponol, respectively, by chemical and physical evidence.     

Two New Diterpens Phenols-7α-Methoxydeoxocryptojaponol and 7β-Hydroxydeoxocryptojaponol

Six crystalline compounds, α-cedrol, β-sitosterol, cryptojaponol sugiol and two new diterpene phenols were isolated from the hexane extractive of wood of Juniperus formosana Hayata. Two new phenolic derivatives of deoxocryptojaponol were established as 7α-methoxydeoxocryptojaponol and 7β-hydroxydeoxocryptojaponol, respectively, by chemical and physical evidence.     

Carbon Magnetic Resonance Spectra of α, β, γ, δ- and α, β, α′, β′- Unsaturated Ketones

Carbon-13 spectra of a series of 26 unsaturated ketones (ortho- and para-cyclo-hexadienones and corresponding open-chain analogues) have been measured by Fourier-transform. Pulse spectroscopy. A complete analysis has been achieved by means of double resonance experiments using noise-modulated and coherent off-resonance proton irradiation and with the aid of non-decoupled spectra. Chemical shifts are interpreted in terms of charge distribution in the dienone system and of methyl substituent effects. Carbon chemical shifts were also obtained for O-protonated ortho- and para-cyclohexadienones. One-bond and long-range carbon-proton and carbon-fluorine spin coupling constants are reported for several compounds.     

Experimental and Theoretical Studies on the Rearrangement of 2‐Oxoazepane α,α‐Amino Acids into 2′‐Oxopiperidine β2,3,3‐Amino Acids: An Example of Intramolecular Catalysis

Enantiopure β‐amino acids represent interesting scaffolds for peptidomimetics, foldamers and bioactive compounds. However, the synthesis of highly substituted analogues is still a major challenge. Herein, we describe the spontaneous rearrangement of 4‐carboxy‐2‐oxoazepane α,α‐amino acids to lead to 2′‐oxopiperidine‐containing β^2,3,3‐amino acids, upon basic or acid hydrolysis of the 2‐oxoazepane α,α‐amino acid ester. Under acidic conditions, a totally stereoselective synthetic route has been developed. The reordering process involved the spontaneous breakdown of an amide bond, which typically requires strong conditions, and the formation of a new bond leading to the six‐membered heterocycle. A quantum mechanical study was carried out to obtain insight into the remarkable ease of this rearrangement, which occurs at room temperature, either in solution or upon storage of the 4‐carboxylic acid substituted 2‐oxoazepane derivatives. This theoretical study suggests that the rearrangement process occurs through a concerted mechanism, in which the energy of the transition states can be lowered by the participation of a catalytic water molecule. Interestingly, it also suggested a role for the carboxylic acid at position 4 of the 2‐oxoazepane ring, which facilitates this rearrangement, participating directly in the intramolecular catalysis.     

Synthesis of β‐Haloketones by β‐Addition Reactions of α,β‐Unsaturated Ketones with BX3 (X = Br,Cl) as Halide Source

A series of β‐bromoketones and β‐chloroketones were synthesized by the addition reactions of α,β‐unsaturated ketones under BX₃ (X = Br, Cl) and ethylene glycol reaction system. The α,β‐unsaturated ester also was successfully converted to its corresponding β‐bromoester under the reaction condition.     

Unusual Acid-Catalyzed Rearrangement of Two α,α′-Diimino-oximes

2-[2-(Alkylimino)-2-phenylethylidene]pyrrolidines (vinamidines, 3 – 6 ) were obtained either via activation of the corresponding vinologous amide 1 with Meerwein salt and subsequent treatment of the intermediate 2 with an amine, or more directly by acid-catalyzed condensation of the Schiff bases derived from acetophenone with 2-ethoxy-1-pyrroline. Nitrosation of these vinamidines led to α,α′-diimino-oximes. In two cases ( 10 , 11 ), these oximes underwent acid-catalyzed rearrangement with formation of a 5,6,7,8-tetrahydroimidazo[1,2-a]pyridine ring system ( 12 , 13 ). X-Ray analysis of one of these products ( 13 ) and also of one of the vinamidine salts ( 6 ) are presented.     

Synthesis of Some Novel Phenyl Substituted Oxothiazolidin- 1’’,3’’,4’’-thiadiazolo-[3’,4’-b]thiazoline of 3β-Substituted Cholestane

Three title compounds 4a—4c have been synthesized by the cyclodehydration of 1’-benzylidine-4’-(3β-substituted-5α-cholestane-6-yl)thiosemicarbazones 2a—2c with thioglycolic acid followed by the treatment with cold conc. H2SO4 in dioxane. The compounds 2a—2c were prepared by condensation of 3β-substituted-5α-cholestan- 6-one-thiosemicarbazones 1a—1c with benzaldehyde. These thiosemicarbazones 1a—1c were obtained by the reaction of corresponding 3β-substituted-5α-cholestan-6-ones with thiosemicarbazide in the presence of few drops of conc. HCl in methanol. The structures of the products have been established on the basis of their elemental, analytical and spectral data.     

α-Lactams (Aziridinones)

α-Lactams have often been postulated as intermediates in numerous processes. The isolation of the first α-lactam, N-tert-butyl-3-phenylaziridinone, was accomplished in 1962. Since then, further N- and C-3-substituted α-lactams have been synthesized. Most of these very reactive compounds undergo easy thermal decomposition; remarkable is the relative stability of 1,3-di-tert-butylaziridinone, which does not start to decompose below 140°C. The α-lactam ring is opened by nucleophilic reagents. — The correlation of stability and substituents is discussed in the last section. An acyclic, planar or almost planar, charge-delocalized intermediate is suggested to explain the observed effects.