Conversions of polyfunctional 3-amino-1(2H)iso quinolines

The acylation of 3-amino-4-cyano-1(2H)isoquinolines with benzoyl chloride leading to the formation of 1,3 oxazino[4,5-clisoquinoline-6-ones has been studied. Previously undescribed 1-aminopyrimido[4,5-cJisoquinolirt 6-ones have been obtained by the reaction of the appopriate 3-amino-](2H)isoginolones with formamide. Nucleophilic replacement has been carried out with 3-amino-1-chloroisoquinoline by the action of sodium hydroxide, primary alcohols, hydrazine hydrate, and various amines. 1,2,4-Triazino[2,3-b]isoginolone has been synthesized by condensing 2,3-diamino-1 (2H)isoquinolone with mesoxalic acid ethyl ester.     

Convenient access to functionalized vinylcyclopentenols from alkynyloxiranes

Beta,gamma-alkynyl aldehydes, generated in situ by treatment of alkynyloxiranes with a catalytic amount of Sc(OTf)3 or BF3.OEt2, are effectively trapped by a variety of allyl nucleophiles to afford homopropargylic homoallylic alcohols in good yield and selectivity. Such products are used as substrates for the synthesis of functionalized vinylcyclopentenols via enyne metathesis.     

Convenient access to bicyclic and tricyclic diazenes

Heating the tosylhydrazone of an omega-alkenyl ketone or aldehyde to reflux in toluene in the presence of K(2)CO(3) delivered the bicyclic diazene. Irradiation of the diazene converted it to the cyclopropane. This appears to be a generally useful method for the construction of substituted cyclopentanes and cyclohexanes.     

Convenient access to both enantiomers of new azido- and aminoinositols via a chemoenzymatic route

1,2-diacetylconduritol E, (±)-1, through complementary use of Mucor miehei (Lipozyme^® IM) and Candida cylindracea lipases, affords (1S)-1,2-diacetylconduritol E, (+)-1, (1R)-1,2-diacetylconduritol E, (−)-1, (1S)-1,2,4-triacetylconduritol E, (+)-2, (1R)-1,2,4-triacetylconduritol E, (−)-2, with high enantiomeric excesses and chemical yields. Following two different methods, diester (+)-1 has been transformed into azidoinositol (−)-4 to give 1L-4-amino-4-deoxy-chiro-inositol, whereas triester (−)-2 furnished the azidoinositol (+)-13, easily converted into 1L-4-amino-4-deoxy-myo-inositol.     

An easy access to (S)-pyrrolidinones and -pyrrolidines from chiral benzylic malonates

From chiral benzylic malonic acid esters (R)-(+)-4, available with high enantiomeric excesses by enzymatic hydrolysis (PLE acetonic powder), enantiomerically enriched pyrrolidinones 1 and pyrrolidines 2 were prepared. This rapid and competitive method was developed via enol ether formation, and subsequent one-pot cyclisation, in good overall yield.     

A Convenient access to thienyl‐substituted phthalazines

A synthesis of 1‐alkoxy‐ and 1‐amino‐ substituted 4‐(2‐thienyl)‐phthalazines is described from halo‐derivatives of 4‐(2‐thienyl)‐l‐(2H)‐phthalazinone 3.     

Synthesis of benzazepines and their rearrangement to quinolines and pyrrolo(2,3-b) quinolines

BECKMANN or SCHMIDT rearrangement of ethyl trans-4-oxo-1-phenyl-2-tetralincarboxylate ( 2 ) affords ethyl trans-2,3,4,5-tetrahydro-2-oxo-5-phenyl-1H-benzo [b] azepine-4-carboxylate ( 4 ). Mild treatment of trans-2,3,4,5-tetrahydro-1-methyl-2-oxo-5-phenyl-1 H-benzo-[b] azepine-4-carboxylic acid ( 7 ) with thionyl chloride and pyridine in dimethylformamide and subsequent reaction with an amine yields the corresponding benzazepine-4-carboxamide. If he it is applied during the preparation of the acid chloride, rearrangement occurs yielding cis and trans derivatives of hydrocarbostyril. 2,3,4,5-Tetrahydro-1,4-methano-1-methyl-5-phenyl-1 H-benzo-[b] azepinium chloride ( 25 ) reacts with primary or secondary amines to cis-tetrahydroquinoline derivatives. When heated above its melting point, trans-4,5-dihydro-2-methylamino-5-phenyl-3H-benzo-[b] azepine-4-carboxylic acid ( 29 ) rearranges with elimination of water to a mixture of cis-and trans-2,3,3a,4-tetrahydro-1-methyl-2-oxo-4-phenyl-1H-pyrrolo [2,3-b] quinoline ( 32 and 31 ). The reduction of 31 was investigated. The mechanisms of the rearrangements are discussed.     

Convenient access to substituted acridines by a Buchwald-Hartwig amination

A convenient, high yield procedure for the synthesis of anthranilic acids carrying a variety of different substituents as well as their straightforward transformation into the corresponding 9-chloroacridines could be established by using modified Buchwald-Hartwig amination conditions.     

Convenient approach to chiral 4-monosubstituted 1,3-oxazolidine-2-thiones

Chiral 4-monosubstituted 1,3-oxazolidine-2-thiones are regarded as one of the modified version of Evans auxiliaries in asymmetric aldol condensation, which can generate two adjacent chiral carbon centers in one time They have advantages over Evans auxiliaries in some aspects, however, their application is highly limited by their preparation approaches as toxic or flammable chemicals are involved. Here, a mild and applicable procedure for preparing the chiral oxazolidine-2-thione auxiliaries has been developed in this article. Potassium ethylxanthate and the corresponding chiral amino alcohols as the starting material in absolute ethanol are mixed and the mixture are heated under reflux for 1?h in open air to provide 1,3-oxazolidine-2-thiones chiral auxiliaries in moderate to excellent yields.     

Convenient method to access new 4,4-dialkoxy- and 4,4-diaryloxy-diaza-s-indacene dyes: Synthesis and spectroscopic evaluation

A straightforward method for the synthesis of original 4,4-dialkoxy- or 4,4-diaryloxy-diaza-s-indacenes (BODIPY) derivatives obtained by treatment of BODIPY 1 with various alcohols in the presence of AlCl3 is described. The novel compounds are characterized by spectroscopic properties similar to those of the parent BODIPY 1, absorption and emission spectra with similar band shapes, high molar absorption coefficients (epsilon lambda max approximately 80,000 M(-1) cm(-1)), and for most of them high fluorescence quantum yields (Phi exp from 0.52 to 0.71). Among all of the new compounds synthesized, the dye 2 h exhibits higher fluorescence quantum yield (0.71) and lifetime (4.09 ns) than compound 1 and a good chemical stability toward conditions compatible with biological cell-based assays.     

Enzymatic oxidation of para-substituted arenes: access to new non-racemic chiral metabolites for synthesis

A series of para-substituted benzene derivatives were subjected to whole-cell fermentation with Escherichia coli JM109 (pDTG601), an organism expressing toluene dioxygenase (TDO). Several compounds proved to be excellent substrates for TDO, including 4-bromo-phenylacetylene, 4-bromobenzaldehyde, 4-bromobenzyl alcohol and 4-bromo-allylbenzene. Some of the first para-functionalized diene diols produced using TDO, are useful substrates for further synthetic manipulations, including their use in the potential synthesis of complex natural products.     

Efficient C-3 functionalization of 4-dimethylaminopyridine (DMAP). A straightforward access to new chiral nucleophilic catalysts

Herein, the straightforward C-3 functionalization of 4-dimethylaminopyridine (DMAP) backbone is disclosed. An efficient halogen-metal exchange procedure from 3-bromo DMAP 1 is reported providing a large panel of C-3 functionalized DMAPs. In addition, a Pd-catalysed C–N cross-coupling reaction is also described furnishing new 3-amino DMAPs. These new functionalization pathways led to the resolution-free synthesis of three new chiral DMAP catalysts in few steps and a good overall yield. These new catalysts were evaluated into the Steglich rearrangement giving modest enantioselectivities (up to 20% ee).     

Synthesis of new chiral 2-functionalized-1,2,3,4-tetrahydroquinoline derivatives via asymmetric hydrogenation of substituted quinolines

The asymmetric hydrogenation of a series of quinolines substituted by a variety of functionalized groups linked to the C2 carbon atom is providing access to optically enriched 2-functionalized 1,2,3,4-tetrahydroquinolines in the presence of in situ generated catalysts from [Ir(cod)Cl]₂, a bisphosphine, and iodine. The enantioselectivity levels were as high as 96% ee.     

Model studies and a new melt polycondensation route to poly-bisphenol a–iso/terephthalate (polyarylate)

Alternate syntheses of polyarylate from dimethyl iso/terephthalate (DMI/DMT) and bisphenol-A (BPA) or bisphenol-A diacetate (BPAOAc) were investigated using a variety of catalysts. The model exchange of DMT with 4-t-butylphenol with loss of methanol proceeded moderately rapidly at rather low temperature (170°C) to produce to mono- and di-t-butylphenyl terephthalates. Dibutyltin oxide is the preferred catalyst. Alkali metal phenoxides are almost as effective but were less soluble. The model reaction of DMT with 4-tert-butylphenyl acetate involving loss of methyl acetate gave comparable results using dibutyltin oxide as catalyst. Based on these model results, polycondensations of DMI/DMT with BPAOAc under optimal conditions, gave polyarylate having an inherent viscosity 0.34 dL g^?1 in quantitative yield and light brown color. Polycondensation with BPA was unsatisfactory in terms of yield, molecular weight, and color.     

A convenient access to chiral and racemic (Z)-1-bromo-3-benzoxy-1-butene

The conversion of propargylic trimethylsilyl ether 3 into (Z)-1-bromo-3-benzoxy-1-butène 1 was achieved by hydroboration with pinacolborane followed by successive treatment with bromine and DBU. The key step of the chiral synthesis involves the asymmetric reduction of the α,β-unsaturated ketone 7 with (−)-diisopinocampheylchloroborane [(−)-Ipc₂BCl].     

Efficient access to chiral β-arylamides via asymmetric 1,4-additions of potassium trifluoro(organo)borates

This paper describes an efficient enantioselective conjugate addition of highly stable potassium trifluoro(organo)borates to α,β-unsaturated amides. This reaction, catalyzed by chiral rhodium(I) complexes affords Michael adducts with high yields and enantiomeric excesses up to 95%.     

Convenient and easy access to 2-hydroxycyclopent-2-enones from acylcyanohydrins

A convenient access to 2-hydroxycyclopentenones was designed from acylcyanohydrins, by using titanacyclopropane complexes as nucleophilic partners and an intramolecular aldol condensation in basic conditions. The development of a one-pot procedure allows a step- and atom-economic process, and the use of Grignard reagents other than ethylmagnesium bromide provided valuable 3,4-disubstituted 2-hydroxycyclopentenones. The utility of the hydroxy group was illustrated by further functionalization of the α-position using palladium-mediated cross-coupling reactions.     

Convenient access to sterically hindered C2 chiral 2,2,5,5-tetraphenyltetrahydrofuran-3,4-diols: intramolecular selective 1,4-cyclocondensation of (2R,3R)- and (2S,3S)-1,1,4,4-tetraphenylbutanetetraols

Sterically hindered C₂ chiral (3R,4R)- and (3S,4S)-2,2,5,5-tetraphenyltetrahydrofuran-3,4-diols have been conveniently prepared in a very high yield via heterogeneous intramolecular selective 1,4-cyclocondensation of (2R,3R)- and (2S,3S)-1,1,4,4-tetraphenylbutanetetraol in concentrated hydrohalic acids, respectively. Preliminary examination of additives for the Barbas–List reaction showed that in certain cases, the hindered C₂ chiral tetrahydrofuran-3,4-diols were better chiral auxiliaries than enantiopure (R)- and (S)-1,1′-bi-2-naphthols.