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Only in the case of (IVc) a slight amount of the γ-adduct is obtained due to steric effects.

A novel rhodium-catalyzed conjugate addition of indium reagents to electron deficient olefins is reported. The reaction takes place in THF/MeOH at 110 °C using arylindium dichlorides, a rhodium(I)-binap complex as catalyst, and α,β-unsaturated ketones and lactones in good yields (45–94%). The addition of MeOH is crucial for an efficient transformation and NMR studies seem to indicate that promotes the catalytic cycle leaving the indium organometallic unaltered. The use of chiral non-racemic ligands allows performing the reaction with moderate enantioselectivities.

Microwave irradiation of a stoichiometric amount of Lawesson’s reagent in the presence of o-aminophenols, o-aminothiophenols, o-phenylenediamines, or catechols leads to benzoxazaphosphole-, benzothiazaphosphole-, benzodiazaphosphole-, and benzodioxaphosphole-2-sulfides, respectively, in good yields in a fast and direct way under solventless conditions. The procedure requires short reaction times and is similar for all reagents; thus it may be used in parallel synthesis.

A highly efficient, microwave-assisted, solvent-free synthesis of neoflavonoids is developed.

Four novel pyrroloiminoquinone alkaloids that differ from members of the discorhabdin/prianosin family for having an allylic alcohol functionality in place of the enone system, epinardins A-D (8–11), have been isolated from undetermined deep-water green demosponges collected in pre-Antarctic waters near the Crozet Islands. Relative stereochemistry has been fully assigned from high-field NMR spectra. Epinardin C (10) proved strongly cytotoxic towards doxorubicin-resistant L1210/DX tumoural cells in vitro.

They function as potent inhibitors of glycoproteins; including DC-SIGN, which facilitates the spread of viruses such as HIV, Hepatitis C, or Ebola; or CETP, which in its inhibited state counteracts atherosclerosis. Furthermore, they have been reported to open calcium channels; or serve as highly selective antagonists for diverse receptors, for example Kinin B1, which is associated with inflammation and pain in septicemia. An example of a promising dihydroquinoxalinone is GW420867X, a non-nucleoside HIV-1 reverse transcriptase inhibitor, which is currently in clinical trials. Furthermore, due to the similarity in their structure, tetrahydroquinoxalines are used as models for tetrahydrofolic acids (coenzyme F) and their derivatives, for example, leucovorine. The latter serves as a “rescue agent” in chemotherapy together with methotrexate. Even though it is only the natural diastereomer of leucovorine that acts as a competitive inhibitor, and the possibility that long-term use of the unnatural diasteromer may be toxic, leucovorine is still generally used as a racemate due to the lack of alternative synthetic methods. Despite the great importance of the tetahydroquinoxalines and dihydroquinoxalinones there are only very few enantioselective synthetic routes. To date efficient synthetic methods include catalytic reactions or solid-phase synthesis. However, they generally require multiple reaction steps and the introduction of a chiral amino alcohol or a corresponding amino acid. With particular emphasis on economic and ecologically valuable processes, asymmetric hydrogenation represents a highly efficient and atom-economic approach. General, catalytic, enantioselective hydrogenations of quinoxalines and quinoxalinones are not known, yet they represent the simplest method for synthesizing optically active tetrahydroquinoxalines and dihydroquinoxalinones. To date only the catalytic enantioselective reduction of 2-methylchinoxaline has been described. However, for instance in the case of DC-SIGN, as is often the case with tetrahydroquinoxalinones, the ones with aromatic substituents in the 2position are more biologically active. Therefore, we decided to examine a general, catalytic, enantioselective reduction of both quinoxalines and quinoxalinones. In particular, we wanted to concentrate on arylsubstituted derivatives, as these have been shown to be especially biologically active. As our initial work towards a metal-catalyzed, asymmetric reduction did not deliver the desired results with regard to high reactivity and selectivity, we decided to also examine metal-free transfer hydrogenations. 16] Here, the initial experiments showed that various Bronsted acids such as diphenylphosphate are able to catalyze the transfer hydrogenation of quinoxaline 1a to the corresponding 2-phenyl-tetrahydroquinoxaline 3a in the presence of the Hantzsch dihydropyridine 2a as a hydride source. Further, it was shown that the concentration of the solvent is a determining reaction parameter, especially with regard to the reactivity: The reactivity continuously increases with increasing solvent concentration. The following studies concentrated on the development of the first asymmetric variant in which the chiral phosphoric [a] Prof. Dr. M. Rueping, Dr. F. Tato, F. R. Schoepke Institute of Organic Chemisty, RWTH Aachen Landoltweg 1, 52074 Aachen (Germany) Fax: (+49)241-809-2127 E-mail : magnus.rueping@rwth-aachen.de Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/chem.200902907.

Cyanoaromatic compounds react with anthranilonitrile in a domestic microwave oven affording good yields of the corresponding 4-aminoquinazolines in a very short irradiation time.

C'mon 1,2-dione: A new diastereo- and enantioselective Lewis base catalyzed domino Michael/aldol reaction converts alpha,beta-unsaturated aldehydes and 1,2-diones into chiral bicyclo[3.2.1]octane-6-carbaldehydes. The products are produced in good to excellent enantioselectivities (90-98 % ee) and can be transformed into bicyclic diols and triols. Additionally, a retro-aldol cyclization provides access to valuable tetrahydrochromenones (see scheme).

An efficient and simple procedure for the syntheses of 4-aryl-1,2,3,4-tetrahydroisoquinolines and 1-aryl-2,3,4,5-tetrahydro-3-benzoazepines has been developed. The approach uses easily available starting materials and requires just three steps. The hydroamination of an enol carbamate is the key step. This general and direct method has been applied to the total synthesis of the natural alkaloid cherylline and to biologically active 3-benzoazepines as well.

2-Thiazolines are synthesized from carboxylic acids and 1,2-aminoalcohols in the presence of Lawesson's reagent under solventless conditions. The developed method is valid for either substituted or unsubstituted aminoalcohols and a wide variety of aromatic, heteroaromatic and aliphatic carboxylic acids; thus it constitutes a general synthetic method for these kinds of compounds. The role of Lawesson's reagent is dual: to transform the 1,2-aminoalcohol into 1,2-aminothiol and to activate its reaction with the carboxylic acid leading to the formation of a thiazoline ring, all in one pot.

We report herein an efficient and simple route to synthesize 1-nosyl 3,3-dichloro-β-lactams using a Staudinger reaction between N-nosyl imines and dichloroketene. The resulting dichloroazetidines were opened to afford highly functionalized building blocks.

A simple and efficient method has been developed for the synthesis of various pyrazolo[3,4-d]pyrimidines by using microwave irradiation under solvent-free conditions. The advantages of applying microwave irradiation compared with the classical method were demonstrated. The structures of all the compounds were confirmed by the usual techniques and, in two cases, by X-ray analysis. The compounds did not display appreciable ability to inhibit xanthine oxidase activity. Screening for antifungal activity showed that some derivatives were active against four fungi, with more significant results for Botrytis.

Lawesson's reagent acts as an efficient promoter in the solvent-free microwave-assisted synthesis of 2-substituted benzoxazoles from carboxylic acids and 2-aminophenol, and thus, constitutes a general synthetic method for these compounds. This new application of Lawesson's reagent is valid also for benzothiazoles with very high efficiency level. A variety of aromatic, heteroaromatic and aliphatic carboxylic acids react under the conditions developed with good yields in all cases. Thiobenzoic acid is a good alternative for microwave-assisted synthesis of 2-phenylbenzox-azole and 2-phenylbenzothiazole in the absence of solvents.

[reaction: see text] Eco-friendly direct solvent-free synthesis of flavones is achieved by microwave irradiation of phloroglucinol and beta-ketoesters. Heating with microwaves versus under classical conditions was shown to be higher yielding, cleaner, and faster. The reaction goes through a cycloaddition of an alpha-oxo ketene intermediate followed by an uncatalyzed thermal Fries rearrangement.

The effect of electrostatic interactions on the complexation of ionic guests by charged β-cyclodextrin (βCD) derivatives is reviewed. Special attention is paid to the numerous studies concerning the effect of electrostatic interactions on (i) the complexation of fluorescent and UV probes; (ii) the catalytic and chiral recognition properties of βCD derivatives; and (iii) the complexation of two bile salts (sodium cholate, NaC, and sodium deoxycholate, NaDC). The formation of three-in-one complexes between NaC and alkyldiamino βCD derivatives is also presented.