Letters in Organic Chemistry - Volume 1, Issue 2, 2004

A Barbier-type allylation of aldimines by allylic acetates in the presence of zinc dust and a simple cobalt halide catalyst takes place in acetonitrile to give the corresponding homoallylic amines in good yields.

Niobium enolate of oxazolidinone 2 was generated by the combination of NbCl5 and a tertiary amine, which then reacted with benzaldehyde and aldimines. The products were obtained in good yields.

The condensation reactions of 4-methylpyrimidine and methylpyrazine with p-anisaldehyde have been studied in NaOH 5M in the presence of catalytic amount of a quaternary ammonium salt (“quat”). This study seems to give credit to a PTC/OH extraction process where an hydroxide ion would be transferred into the “pseudo organic phase” consisted by liquid reagents. However, an IPTC process cannot be ruled out for so Read More

As a new direct functionalization of guanidines, the N-allylic substitution of guanidines was studied. The nitrogen atom of guanidine derivatives having two Nelectron- withdrawing substituents acted as a reactive nucleophile in the allylic substitution.

A highly efficient and stereoselctive hydrosilylation and hydrostannyla-tion of terminal alkynes was developed in air and water that provided an aqueous one-pot, hydrostannylation/ conjugate addition

The heterogeneous oxidation of cyclooctene with H2O2 catalyzed by Mnporphyrins embedded in polydimethylsiloxane (PDMS) and organically modified silicates (ORMOSILs), in the presence of hexafluoroacetone hydrate (HFAH) as cocatalyst, has been studied in supercritical carbon dioxide (scCO2) at 40°C and 20 MPa. Complete olefin conversion may be obtained with the formation of cyclooctene oxide as sole product, emp Read More

Two routes are examined to achieve the synthesis of a glutarimide possessing a quaternary asymmetric centre with good stereocontrol. It appears that the first one, involving enantioselective Michael addition of cyano-4-(3,4-dichlorophenyl)butanoate on allyl acrylate is the most interesting in terms of cleanness of reactions and stereocontrol. The best system involves a quinidine derived catalyst at - 40°C with potassium hydro Read More

A novel synthesis of 2-[(dialkylcarbamoyl)methylene]tetrahydrofuran derivatives 3-8 by Pd-catalyzed oxidative carbonylation of 4-yn-1-ols 1 in the presence of dialkylamines 2 is reported (2:1 molar ratio = 2). Reactions are carried out in 1,2- dimethoxyethane (DME) at 100°C and under 20 atm (at 25°C) of a 4:1 mixture of CO and air, in the presence of catalytic amounts of PdI2 (1 mol % with respect to 1) in conjunction with 10 Read More

Trihexyl(tetradecyl)phoshonium decanoate was shown to be an effective promoter for the Henry nitroaldol reaction of nitromethane with aromatic aldehydes. A mechanism is proposed involving Lewis acid activation of the carbonyl group proceeding through a trigonal-bipyramidal intermediate. Evidence in accord with the postulated pathway as opposed to a base or phase transfer-mediated route involving proton transfer from t Read More

1-Phenylethenyl phosphate derivatives of the monoester type were synthesized via the Perkow reaction. Among them, 2-(2,4-difluorophenyl)ethenyl phosphate was found to be obtained as a pure salt. It turned out that this compound and 2-phenylethenyl phosphate can transfer their phosphoryl groups to AMP in pyridine at elevated temperatures to give ADP.

Asymmetrically substituted bis(iminophosphoranes) derived from 1,2- bis(diphenylphosphino)ethane are prepared by Michael-type addition of easily available N,P,P-trisubstituted aminophosphanes to P-vinyl iminophosphoranes. Similarly P-alkylations of aminophosphanes with P-vinyl phosphane oxides and sulfides are also disclosed.

A new series of ferrocenyl diphosphines have been synthesized by Suzuki coupling of diboronic acid of ferrocene with bromo-substituted triphenylphosphine oxides, followed by reduction with HSiCl3.

The synthesis of unsymmetrical ferrocene 1,1’-diamides via homogeneous catalytic aminocarbonylation of 1,1’-diiodo-ferrocene is described. The products were obtained in good yields in a one-pot reaction by using two different secondary amines as nucleophiles simultaneously.

The synthesis is described of 1-chloromethyl-5-hydroxy-1, 2-dihydro-3H-benz [e] indole (seco- CBI)- pyrrole polyamide conjugates (1-4) which were labeled with a fluorescent Fmoc moiety to evaluate their cellular uptake. Confocal laser scanning microscopy (CLSM) indicates that these DNA minor groove-binding agents localize in the cytoplasm and organelles.

To overcome the problem of depurination in oligoDNA synthesis, we tried to fine-tune the acid lability of the DMTr group by adding a substituted styryl group on the phenyl ring. The styryl groups could buffer the electron donating nature of the methoxy group and enabled the fine-tuning of the acid lability.

C-Protected β-enamino acids (I) reacted with one equivalent of Nhalosuccinimides (NXS) to furnish their α-halogenated derivatives (II). These compounds were then successfully transformed into halogenated uracil derivatives (III) through reaction with triphosgene, followed by 5-membered ring-opening under acidic conditions.

Synthesis of Iboga-functionalized isoquinuclidine ring system and alkylated derivatives from commercially available 3-ethyl-pyridine, is reported. The key-step for isoquinuclidine synthesis is a cycloaddition between methyl acrylate and N-benzyl-3- ethyl-5,6-dihydropyridine obtained in situ from N-benzyl-3-ethyl-4-methoxy-1,4,5,6- tetrahydropyridine. Further treatment of isoquinuclidine lithium enolate with appropriate electrophil Read More

Oxidases present in plant cultured cells of Catharanthus roseus can hydroxylate saturated centers of natural products without double bond activation. When starting materials were 1,8- or 1,4-cineole, secondary and tertiary alcohols were produced and identified using NMR and mass spectroscopy. Our results indicate that hydroxylation position and stereochemistry are determined by the biotransformation organism.

The regioselectivity of the acetylation of D-xylopyranosides attached to polyethylene glycol monomethyl ether (MeOPEG) catalyzed by lipases from Pseudomonas cepacia and Candida antartica in organic solvent was examined. Partially acetylated derivatives can be obtained with high regioselectivity by acetylation or deacetylation in the presence of the appropriate lipase.

Four biotransformed products of resibufogenin were obtained after 4 days of incubation with cell suspension cultures of Platycodon grandiflorum. On the basis of chemical and spectral data, their structures were elucidated as 3-epi-resibufogenin, marinobufagin, 1β-hydroxy-resibufogenin, and 3-epi-marinobufagin respectively, among which the latter two compounds are new. These compounds were found to exhibit potent cyto Read More