Structural Modifications of Chaparrinone Using Benzeneseleninic Anhydride. Preliminary communication

Treatment of chaparrinone triacetate with benzeneseleninic anhydride afforded in addition to the Δ^14,15-dehydro compound two products arising from angular hydroxylation at C(5). The mechanism of this reaction is discussed. The corresponding deacetylated compounds do not display significant antineoplastic activity.     

The unexpected course of the reaction of steroid sapogenins with diacetoxyiodobenzene and BF3·Et2O in formic acid

The reaction of steroid sapogenins of both the 25R and 25S series with diacetoxyiodobenzene and BF₃·Et₂O in formic acid produced a mixture of an equatorial 23-formyloxysapogenin, a 16β,23:23,26-diepoxy-22-one and a bisnorcholanic lactone. The outcome of this reaction, that drastically differs from the same reaction in acetic acid, opens up new possibilities for the transformation of the side chain of steroid sapogenins.     

Synthesis of o-benzoquinones derived from [2.2]- and [3.3]paracyclophanes

Oxidation of [2.2]- and [3.3]paracyclophanols with benzeneseleninic anhydride readily afforded the corresponding cyclophane-o-quinones which showed the intramolecular charge-transfer interactions.     

Studies on the terpenoids and related alicyclic compounds—XXII: Stereochemical study on the angular hydroxylation of polycyclic ketones using benzeneseleninic anhydride

Introduction of an OH group to the tertiary carbon of simple ketones (1, 2 and 6), furanoeremophilane-type ketones (12–19), and tricyclic ketones (20–22) by the use of benzeneseleninic anhydride is described. 10β-Hydroxy compounds were obtained in the case of 12–14 and 20–22. 10α-Hydroxy compounds were obtained in the case of 15 and 16. In the hydroxylation reaction of polycyclic ketones using benzeneseleninic anhydride, the results suggest that the thermodynamically more stable product was usually produced as the major product.     

Lead tetraacetate-iodine oxidation of 23-spirostanols

Reactions of 23R- and 23S-23-spirostanols in the 25R and 25S series with lead tetraacetate-iodine were studied. The reactions carried out at low temperature afforded d-seco-iododialdehydes and C₂₂ lactones, while similar reactions performed in refluxing tetrachloromethane yielded 20-chlorolactones and their 21-acetoxy derivatives irrespective of the hydroxyl group configuration at C-23. The reaction mechanisms are discussed.     

An unprecedented 3-D supramolecular framework of {CuCN} coordination polymer based on anhydride: in situ formation of ligand by intramolecular dehydration

Hydrothermal reactions of K₄[Fe(CN)₆]?3H₂O with H₂bimdc (H₂bimdc = benzimidazole-5,6-dicarboxylic acid) afforded a coordination polymer (CP), [Cu(CN)(bimdca)] (1) (bimdca = benzimidazole-5,6-dicarboxylic anhydride), as the first example of the {CuCN}-based CP modified by anhydride. The polymer is characterized by elemental analysis, IR, TG, XRD, and single-crystal X-ray diffraction. In 1, horizontal and vertical parallel chains based on {Cu₂(CN)₄(bimdca)₂} dimer units crisscross resulting in a 2-D network with a (4⁴6²) topology, which is further connected to adjacent 2-D layers generating a 3-D supramolecular framework through intermolecular force between oxygens of anhydride. In addition, 1 exhibits interesting fluorescence and good degradation ability for MB under UV light.     

Heat-Resistant thermosetting polyamide and polymides with styrlpyridine segments derived from 2,2′-(1,4-phenylenedivinylene) bisaminoquinoline

The nitration of quinaldine by fuming nitric and sulfuric acid afforded nitroquinaldine. It was condensed with a half molar amount of 1,4-benzenedicarbaldehyde in the presence of acetic anhydride to yield 2,2′-(1,4-phenylenedivinylene) bisnitroquinoline. The latter was catalytically hydrogenated to the corresponding diamine, PBAQ. The new polyamide and polymides bearing styrylpyridine segments were prepared utilizing PBAQ as starting material. In addition, a model diamide and diimide were synthesized and characterized IR and ¹H-NMR spectroscopy. Inherent viscosities of polymers ranged from 0.31 to 0.60 dl/g. Certain polymer precursors such as a bismaleimide and bisnadimide were synthesized from the reactions of PBAQ with maleic and nadic anhydride, respectively. Their curing behavior was investigated by DTA. Curing of polyamide, polyimides, and polymer precursors at 240°C for 15 h yielded crosslinked polymers. They were stable up to 329–310°C in N₂ or air and afforded a char yield of 67–62% in N₂ at 800°C. © 1994 John Wiley & Sons, Inc.     

Lactonization of epoxyendic anhydride in reactions with amines

Reactions of exo-5,6-epoxybicyclo[2.2.1]hept-5-ene-endo-2,endo-3-dicarboxylic anhydride (epoxyendic anhydride) with acyclic, aromatic, heteroaromatic, and nonaromatic heterocyclic amines afforded the corresponding heterocyclization products, substituted exo-2-hydroxy-5-oxo-4-oxatricyclo[4.2.1.0^3,7]nonane-endo-9-carboxamides (oxabrendanes), whose structure was confirmed by the IR and ¹H and ¹³C NMR (including two-dimensional) spectra. Other approaches to the tricyclic compounds were also examined, in particular via reactions of organic peroxy acids with amido acids obtained by aminolysis of endic anhydride.     

Oxidation of olefins with 2-pyridineseleninic anhydride

2-Pyridineseleninic anhydride, prepared $\text{in situ}$ by oxidation of the corresponding diselenide with iodoxybenzene, is an efficient reagent for the conversion of olefins to unsaturated ketones with retention of the original position of the double bond. This reagent is, therefore, much more reactive towards olefins than benzeneseleninic anhydride. An explanation has been offered.     

25R/25S stereochemistry of spirostane‐type steroidal sapogenins and steroidal saponins via chemical shift of geminal protons of ring‐F

A method based on the differences among the ¹H NMR chemical shifts of geminal protons of ring‐F methylene resonances (H₂‐23, H₂‐24 and H₂‐26) is proposed for ascertaining the 25R/25S stereochemistry of ring‐F unsubstituted spirostane‐type steroidal sapogenins and steroidal saponins. Copyright © 2003 John Wiley & Sons, Ltd.     

Highly selective anti-markownikoff type oxidation of olefinic bonds of allylic alcohol derivatives. Specific synthesis of β-alkoxy α-phenylseleno carbonyl compounds

On treatment with diphenyl diselenide and benzeneseleninic anhydride, 3-$\text{t}$-butyldimethylsiloxy-1-alkenes were converted to the corresponding α-phenylseleno aldehydes exclusively.     

Ferrocene compounds. XXV. Synthesis and characterization of ferrocene‐containing oligoamides,their precursors,and analogues

A general method for preparation of ferrocene‐containing monoamines (5–7) and diamines (10, 11) starting from the corresponding quaternary ammonium iodide 3 and ferrocene mono‐ (4) and dithiaaliphatic acids (8, 9) was developed. Amines obtained have been characterized as acet‐ and benzamides (12–15). The oligoamide precursors (16, 17, 22, 23) were synthesized by reactions of succinic or glutaric anhydride with amines (6, 7, 10, 11). Their conversion into oligoamide analogs (20, 21, 25) failed. The desired diamides (20, 21) were prepared by condensation of amines (6, 7) with alkanedioyl chlorides, (CH₂)_n(COCl)₂ (n = 0, 1, 2, 3). Reactions of diamine 10 with succinic or glutaric anhydride gave amino acids 28—formal monomers for the planned oligomerization. Oligomers 29 were synthesized by condensation of equimolar amounts of diamines 10 and the above mentioned alkanedioyl chlorides in dichloromethane at 0°C. The structure of oligomers 29 was indicated from their IR and ¹H‐NMR spectra in comparison with the model substances 12–28. The degree of polymerization of compounds 29 was determined by ¹H‐NMR end‐group analysis (DP_n = 4–6). © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 25–36, 1999     

1,2-Dihydro-2-thioxo-4H-3,1-benzothiazin-4-one: formation from carbon disulfide and isatoic anhydride

The reaction of isatoic anhydride (1) with carbon disulfide at room temperature unexpectedly afforded 1,2-dihydro-2-thioxo-4H-3,1-benzothiazin-4-one (2). The use of ¹³C-labeled carbon disulfide elucidated that CS₂ was entirely incorporated into the product.     

Mercaptolysis of the E／F Rings of Steroidal Sapogenins： A Concise Synthesis of Δ^20（22）－Furostene－26－thioethers

Lewis acid catalyzed mercaptolysls of steroidal sapogenins was reinvestigated. Besides obtaining the reported 26-thioacetals 5 under milder conditions, a new type of compounds Δ^20(22)-furostene-26-thioethers 6 were also synthesized through the mercaptolysis of steroidal sapogenlns, which can be used to the synthesis of the steroidal molecule with side chains.     

Synthesis of 1,3,4‐Oxadiazoles and 1,3‐Thiazolidinones Containing 1,4,5,6‐Tetrahydro‐6‐pyridazinone

The reaction of 1,4,5,6‐tetrahydro‐6‐pyridazinone‐3‐carboxylic acid hydrazides ( 1 ) with aromatic aldehydes afforded 1,4,5,6‐tetrahydro‐6‐pyridazinone‐3‐carbonyl aromatic aldehyde hydrazones ( 2a‐2g ). Heterocyclic derivatives linked 1,3,4‐oxadiazole obtained by cyclocondensation of 2a‐2g with acetic anhydride in absolute ethanol, and 2a‐2g cyclized with mercaptoacetic acid in DMF in the presence of anhydrous ZnCl₂ afforded the 1,3‐thiazolidinone derivatives. The structures of the new compounds were established by elemental analyses, IR, ¹H NMR and MS spectral data.     

Chemical reactions of cycloalkanespirohydantoins. Part 3. Acid-catalyzed reaction of 4-hydroxy-2-imidazolidinones. Preparation of bis(1,3-diaza-2-oxospiro[4,5]decyl-4) ether

The use of N-carbamoyliminium ion initiated reactions for the generation of spiroimidazolidin-2-ones has been successfully exploited. N₃-Substituted-4-hydroxy-2-imidazolidinones have been treated under acid conditions to give the rearranged imidazolinones. Only in the case of N₃-dialkylaminomethyl-4-hydroxy-5-cyclohexanespiro-2-imidazolidinones upon treatment with trifluoroacetic anhydride/trifluoroacetic acid afforded a mixture containing bis(1,3-diaza-2-oxospiro[4,5]decyl-4) ether with the rearranged imidazolidinone.     

CuBr/Et3N‐Promoted Reactions of 2‐Aminobenzamides and Isothiocyanates: Efficient Synthesis of Novel Quinazolin‐4(3H)‐ones

A series of novel quinazolin‐4(3H)‐one derivatives were efficiently synthesized starting from isatoic anhydride. First, reaction of isatoic anhydride and amines in H₂O at room temperature afforded 2‐aminobenzamides. Then, CuBr/Et₃N promoted reaction of 2‐aminobenzamides and different aryl isothiocyanates in DMF at 80° afforded the title compounds in good yield.     

Oxidation of Phenylhydrazones with Benzeneseleninic Anhydride: A New Mechanistically Interesting Observation

The effects by benzeneseleninic anhydride were studied. An unexpected by-product, 1,4-bis(phenylselanyl)benzene, was isolated from the oxidation reactions. Its formation was suppressed when pyridine was used as the co-solvent. Aryl phenyl selenides were synthesized by reaction of aryl radicals, generated from reduction of aryl diazonium salts, with diphenyl diselenide.     

Reversal of Regioselectivity of Nitrone Cycloadditions by Lewis Acids

The regio‐ and stereoselectivity of cycloadditions of the nitrone 1a and the chiral, sugar‐derived nitrones 13a and 13b with 3‐(prop‐2‐enoyl)‐1,3‐oxazolidin‐2‐one ( 2 ) depends on the nature of the Lewis acid catalyst used. Addition of Lewis acid reverses the regioselectivity of the cycloaddition, and improves the anti‐diastereoselectivity in the case of chiral nitrones. The sterically favored isoxazolidin‐5‐yl‐substituted adducts 3, 4 , and 14 – 17 are produced as the major products in the absence of Lewis acid, while the electronically favored regioisomers with isoxazolidin‐4‐yl substituents ( 5, 6 , and 18 – 21 , respectively) are obtained as major products in the [Ti(OⁱPr)₂Cl₂] catalyzed reactions. The reactions of nitrone 13b with 2 in the presence of other Lewis acids such as ZnCl₂, ZnBr₂, ZnI₂ and MgI₂/I₂ gave both regioisomeric pairs of the diastereoisomers, favoring the 4‐substituted congeners. The diastereoisomeric isoxazolidines 3a – 6a were reduced with NaBH₄ in THF/H₂O with subsequent desilylation to yield the separable diols 9 – 12 . Reduction of the diastereoisomeric isoxazolidines 19a and 18a afforded the chiral alcohols 23 and 22 , the latter of which was analyzed by X‐ray crystallography.     

A new route for the preparation of the 22,23-dioxocholestane side chain from diosgenin and its application to the stereocontrolled construction of the 22R,23S-diol function

The new (22R,23S,25R)-3β,16β,26-triacetoxy-cholest-5-ene-22,23-diol (11a) was synthesized from diosgenin (3) through a synthetic route based on chemoselective RuO₄ oxidation of (25R)-3β,16β-diacetoxy-23-ethyl-23¹,26-epoxycholesta-5,23(23¹)-dien-22-one (9) that afforded (20S,25R)-3β,16β,26-triacetoxycholest-5-ene-22,23-dione (10) which was stereoselectively reduced using NaBH₄. Compound 9 was obtained from the known isomeric 22,26-epoxycholest-5-ene steroidal skeleton 8b by treatment with p-TsOH in toluene, amberlyst-15 or directly from diosgenin by treatment with BF₃·OEt₂/Ac₂O. Chemoselective reduction of the 23-keto group of 10, was attained using NaBH₄/ZnCl₂ at −70 °C to give 23S-14. The NMR spectra of all compounds were unambiguously assigned based on one and two dimensional experiments and the C-22 and C-23 stereochemistry in the diacetate derivative 11b, as well as the structure of epoxycholestene 9 were further established by X-ray diffraction analyses. The new route for the functionalization of the side chain of diosgenin can find application in the synthesis of norbrassinosteroid analogues.