Letters in Organic Chemistry - Volume 7, Issue 5, 2010

Herein we describe a method for the fast cycloaddition reaction of 2H-chromenes with 2-methoxy-1,4- benzoquinones by microwave heating. Using this methodology we have synthesised seven pterocarpans derivatives, five of which are novel compounds. Microwave heating allows significant yield enhancements and reduction of reaction time when compared to traditional methodology.

An efficient synthesis of the azetidinyl-thiazoline fragment of the antifungal and cytotoxic macrolides vioprolides A and C is reported. Key steps of the synthesis include formation of the thiazoline by condensation of N-Alloc- trans (2S,4R)-4-methylazetidine-2-carbonitrile with L-cysteine and formation of the four-membered ring by intramolecular alkylation of a suitably protected N-Alloc derivative prepared from (R)-alaninol.

A new series of 7-fluoro-6-(4-methyl-1-piperazinyl)-2-(thiosubstituted)-4(3H)-quinazolinones was synthesized as potential antitumor agents by multi-step synthesis starting with the commercially available 3-chloro-4-fluoroaniline. The most promising candidate, 7-fluoro-6-(4- methyl-1-thyl-1-piperazinyl)- 2-thioethyl-4(3H)-quinazolinone (5a), was screened in 60 human cancer cells by NCI.

Simple chiral primary amine-thiourea catalysts derived from chiral 1,2-diphenylethylenediamine were found to catalyze direct Michael addition of aromatic ketones to nitroolefins with good enantioselectives (up to 86% ee) and excellent yields (up to 97%) for a broad range of substrates and successfully used in the preparation of (R)-Balcofen.

The isoprene-mediated lithiation of imidazoles bearing a secondary alkyl substituent at the nitrogen (7, 8 and 13) and the subsequent nucleophilic addition to different electrophiles allows the preparation of the corresponding 2- functionalized imidazoles 10, 11 and 14. The presence of a stereogenic center in the alkyl substituent induces diastereoselection during the nucleophilic addition step with a prochiral electrophile (i. Read More

The reaction of 3,4-dihydro-β-carboline 5a with the nitrile oxide generated from 4-fluoro-N-hydroxybenzenecarboximidoyl chloride (6) gave novel adduct 7a that on standing at 26 °C in CDCl3 was isomerized to species 8. As an extension, the reaction of the dihydro-β-carbolines substituted on C(1) (5b-e) afforded the analogous adducts (7b-e). In case of using two equivalents of reagent 6, the corresponding 1,2,4-triazole-2-oxid Read More

This work describes the synthesis of a series of nine 4-thio dibenzosuberone derivatives (10,11-dihydro-5Hdibenzo[ a,d]cycloheptane-5-one derivatives). Ullmann's reaction was used to synthesize six 4-thio dibenzosuberone derivatives 10-15 from 4-iodo dibenzosuberone 9. Compound 9 was synthesized from dibenzosuberone 7 through the use of TTFA [thallium (III) trifluoroacetate] and KI. Hydrolysis of 10 yielded derivati Read More

We report hereby a particularly efficient synthesis of secondary, and tertiary amines respectively, through a direct reductive amination process carried for the first time in a completely aqueous media.

Thiocyanation of various aromatic, heteroaromatic and enolizable ketone compounds has been achieved with ammonium thiocyanate in presence of polystyrene cation exchange resin, Amberlyst-15. All the reactions were carried out in acetonitrile at room temperature.

An efficient procedure of flash heating by microwave irradiation was described for the attachment of 6-O-benzylallosamizoline 8 to chloromethylated Wang resin 7 via its corresponding stannylene intermediate. The reaction rate and loading for compound 8 were significantly enhanced when the microwave irradiation protocol was compared with the conventional heating method.

Three bis urea based acyclic receptors with fixed spacer and varying size of substituents have been synthesized and their binding behavior with different anions are reported along with the selectivity of these receptors towards anions. The fluorescence quenching of the receptors 2 and 3 on binding with anions is also shown. The receptor 1 binds better with Y-shaped AcO¯ ion whereas receptor 3 binds well with Cl¯ ion.

The reaction of ketone, aldehyde, ethyl cyanoacetate and ammonium acetate in polyethylene glycol-600 is reported. The reaction proceeds smoothly in the absence of catalyst to yield 2-Pyridones.

A new method has been developed for the synthesis of acylhydrazines 5a-g by the reduction of unsymmetrical 1,3,4-oxadiazoles 4a-g by using sodium borohydride/acetic acid combination. Later on, acylhydrazines 5a-g were converted to their corresponding sulfonamide derivatives 6a-d.

An improved method for the synthesis of disulfide in water by using periodic acid and sodium hydrogen sulfite was developed.