Facile synthesis of phenyl-capped oligoanilines using pseudo-high dilution technique

Monodispersed phenyl-capped trianiline and tetraaniline were successfully synthesized by the reactions of diphenylamine with acetaldehyde-based Sckiff's bases of N-phenyl-1,4-phenylenediamine and 1,4-phenylenediamine, respectively, in the presence of ammonium persulfate and hydrochloric acid, subsequent deprotonation and reduction with phenylhydrazine. The reaction mechanism probably involves the slow hydrolysis of the Sckiff's bases and subsequent oxidative coupling reactions of the formed ammonium salts with diphenylamine at pseudo-high dilution condition of the salts.

Efficient synthesis and facile polymerization of some cyclic bisphenol o-phthalates

A series of new macrocyclic aromatic esters have been efficiently synthesized from o-phthaloyl dichloride and various bisphenols, and unambiguously characterized by a combination of GPC, MS(FAB), FTIR and NMR. These macrocyclic oligomers undergo facile ring-opening polymerization in the presence of anionic initiators to give high molecular weight polyarylates.

2,4-dinitrophenol as an activating reagent in a facile preparation of cyclic phosphate trimesters

Abstract 2,4-Dinitrophenol was employed with benzyloxy-bis-(diisopropylamino)phosphine to synthesise the cyclic phosphate derivatives of a series of alkane diols (HO–(CH2)n–OH, n=2–6) in good isolated yields. Tetrazole and DNP were compared by 31P NMR spectroscopy for their ability to catalyse the cyclisation at the P(III) stage. Investigation of the phosphate triester stability under various oxidation and chromatographic conditions resulted in the optimisation of the isolation procedures of the chemically unstable cyclic compounds. Conditions for debenzylation were developed to yield the corresponding cyclic phosphodiesters quantitatively. The methodology was further applied to the preparation and isolation of the cyclic phosphate derivative of a carbohydrate.

Facile Syntheses of Three Major Metabolites of Thioridazine

NMR studies were conducted with the aim of determining the diastereoisomeric ratio of a commercially supplied sample of mesoridazine (MES) and to compare the results with a freshly synthesised sample of MES. The results indicated that the commercially supplied MES consisted almost entirely of one diastereoisomeric pair, which was in agreement with previous findings reported by Eap et al. (J Chromatogr 669:271-279, 1995). The synthesised sample of MES was analysed by NMR in two stages: 1) as the initial product isolated as the free base from the direct synthesis, and 2) as the free base isolated from the crystallised besylate salt of the synthetic product. The NMR results show that the initial synthetic product consisted of two equal pairs of diastereoisomers. The diastereoisomeric pairs were further separated by the addition of the chiral shift reagent (R)-(-)-N-(3,5 dinitrobenzoyl)-alpha-benzylamine to reveal equal quantities of all four enantiomers, clearly observed at the methyl sulfoxide proton peak of the NMR scan. The sample obtained from the crystallisation of MES besylate, however, indicated a significant difference, with a diastereoisomeric ratio of 75:25. The results suggest that MES besylate undergoes preferential crystallisation of one pair of diastereoisomers, with the other pair remaining in solution. (C) 2004 Wiley-Liss, Inc.

Facile synthesis of two diastereomeric indolizidines corresponding to the postulated structure of alkaloid 5,9E-259B from a Bufonid toad (Melanophryniscus)

A short synthesis of the postulated structure for indolizidine alkaloid 259B with the hydrogens at C5 and C9 entgegen has been achieved with complete control of stereochemistry at C5. Both diastereoisomers at C8 were obtained, but neither proved to be the natural product. The comparison of the mass and FTIR spectral properties of the synthetic compounds to those of the natural material strongly suggest that the gross structure is correct and that the difference may be a branch in the C5 alkyl side-chain. The GC-retention times of the two synthetic compounds were markedly longer than that of the natural 5,9E-259B.

Facile biocatalytic reduction of the carbon-carbon double bond of 5-benzylidenethiazolidine-2,4-diones. Synthesis of ( )-5-(4-{2-[methyl(2-pyridyl)amino]ethoxy}benzyl)thiazolidine-2,4-dione (BRL 49653), its (R)-(+)-enantiomer and analogs.

Cantello, Barrier C. C.; Eggleston, Drake S.; Haigh, David; Haltiwanger, R. Curtis; Heath, Catherine M.; Hindley, Richard M.; Jennings, Keith R.; Sime, John T.; Woroniecki, Stefan R. SmithKline Beecham Pharmaceuticals, Surrey, UK. Journal of the Chemical Society, Perkin Transactions 1: Organic and Bio-Organic Chemistry (1994), (22), 3319-24. Publisher: Royal Society of Chemistry, CODEN: JCPRB4 ISSN: 0300-922X. Journal written in English. CAN 122:105736 AN 1995:237497 CAPLUS (Copyright (C) 2009 ACS on SciFinder (R)) Abstract A novel biotransformation system for the redn. of carbon-carbon double bonds in 5-benzylidenethiazolidine-2,4-diones to give the corresponding 5-benzylthiazolidine-1,4-diones, using whole cells of red yeasts, is described. These reduced compds., which are recovered in good yield, are of potential use in the treatment of non-insulin dependent diabetes mellitus. The mild reaction conditions developed allow redn. of 5-benzylidenethiazolidine-2,4-diones contg. other functionalities which are not compatible with alternative redn. methods. The biocatalytic redn. is enantioselective and the synthesis of R-(+)-5-(4-{2-[methyl(2-pyridyl)amino]ethoxy}benzyl)thiazolidine-2,4-dione by Rhodotorula rubra CBS 6469 and structure confirmation by X-ray crystallog. is detailed. Optimization of reaction conditions (including immobilization) for these whole cell redn. system is described.

Rhodium carbenoid O-H insertion reactions with phenols; a facile method for the synthesis of trialkyl 2-aryloxyphosphonoacetates and their use in the preparation of 2-aryloxy-3-phenylpropanoates

Substituted phenols undergo a facile Rh carbenoid-mediated O-H insertion reaction with (EtO)2P(O)C(:N2)CO2R (I; R = Et, Me) to give 44-86% 2-aryloxyphosphonoacetates II (R1 = e.g., H, 4-Me, 4-Cl, 2-OH, 4-PhCH2O). Phenols contg. strongly electron withdrawing groups, bulky ortho-substituents or certain ortho-heteroatom substituents show reduced or variable yields. Catechol affords a mono-adduct which cyclizes to lactate III. Aniline inserts preferentially and exclusively over phenol in a competition reaction with I (R = Et) to give (EtO)2P(O)CH(NHPh)CO2Et. II are versatile intermediates in a prepn. of 2-aryloxy-3-phenylpropenoates IV by Wadsworth-Emmons reaction with benzaldehydes R2C6H4CHO (R2 = PhCH2O, 2-Cl, H). Dissolving Mg metal redn. provides a mild method for the conversion of propenoates IV into the corresponding propanoates.

Facile in situ synthesis of nanofluids based on ionic liquids and copper oxide clusters and nanoparticles

Two stable nanofluids comprising of mixed valent copper(_I,_II) oxide clusters (<1 nm) suspended in 1-butyl-3-methylimidazolium acetate, [C(₄)mim][OAc], and copper(_II) oxide nanoparticles (<50 nm) suspended in trioctyl(dodecyl) phosphonium acetate, [P-₈₈₈₁₂][OAc], were synthesised in a facile one-pot reaction from solutions of copper(_II) acetate hydrate in the corresponding ionic liquids. Formation of the nanostructures was studied using ¹³C NMR spectroscopy and differential scanning calorimetry (DSC). From a solution of Cu(OAc)₂ in 1-ethyl-3-methylimidazolium acetate, [C₂mim][OAc], crystals were obtained that revealed the structure of [C₂mim][Cu₃(OAc)₅(OH)₂(H₂O)]center dot H₂O, indicating the formation of copper hydroxo-clusters in the course of the reaction. Synthesised nanostructures were studied using transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Physical properties of the prepared IL-nanofluids were examined using IR and UV-VIS spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and densitometry.