René Grée
University of Rennes
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Featured researches published by René Grée.
Cancer Research | 2006
Florence Manero; Fabien Gautier; Tristan Gallenne; Nicolas Cauquil; Danielle Grée; Pierre-François Cartron; René Grée; François M. Vallette; Philippe Juin
A functional imbalance between proapoptotic Bax and antiapoptotic Bcl-2 is likely to participate in the resistance of cancer cells to therapy. We show here that ethyl 2-amino-6-bromo-4-(1-cyano-2-ethoxy-2-oxoethyl)-4H-chromene-3-carboxylate (HA14-1), a small organic compound recently proposed to function as an inhibitor of Bcl-2, increases the sensitivity of human glioblastoma cells to radiotherapy and chemotherapy. This sensitizing effect is lost if Bcl-2 expression, but not Bcl-xL expression, is knocked down or if cells only express a mutant of Bax that does not interact with Bcl-2. This points to a specific Bcl-2 inhibitory function of HA14-1 and implies that it selectively involves hindrance of Bcl-2 binding to Bax, which HA14-1 inhibits in cell-free assays and in cells in receipt of an apoptotic stimulation. Moreover, HA14-1, in combination with a cytotoxic treatment, slows down the growth of glioblastoma in vivo. Thus, the inhibition of Bcl-2 achieved by HA14-1 might improve treatment outcome.
Tetrahedron Letters | 1981
A. Monpert; J. Martelli; René Grée; R. Carrie
Resume Chiral electrophilic cyclopropanes are prepared, in high enantiomeric excess (e.e > 90 %) starting from the optically active complexes 3a and 3b . A simple and efficient method. for the resolution of the key intermediate complex 1 is described.
Tetrahedron Letters | 1982
Hassan Abadallah; René Grée; R. Carrie
Resume Chiral oxazolidines 2 are very simple and highly efficient inducing groups for asymmetric synthesis during cycloaddition reactions. Chiral Formyl cyclopropanes are easily obtained in high enantiomeric excess (⩾ 90 %).
Journal of Organic Chemistry | 2011
B. V. Subba Reddy; Prashant Borkar; J. S. Yadav; B. Sridhar; René Grée
Homoallylic substrates such as (E)-6-arylhex-3-enyl alcohols, N-tosylamides, and thiols undergo smooth cross-coupling with various aldehydes in the presence of 10 mol % Sc(OTf)(3) and 30 mol % TsOH to afford the trans-fused hexahydro-1H-benzo[f]isochromenes, N-tosyloctahydrobenzo[f]isoquinolines, and hexahydro-1H-benzo[f]isothiochromenes, respectively. However, the cross-coupling of (Z)-olefins such as 6-arylhex-3-enyl alcohols, N-tosylamides, and thiols with aldehydes affords the corresponding hexahydro-1H-benzo[f]isochromenes, N-tosyloctahydrobenzo[f]isoquinolines, and hexahydro-1H-benzo[f]isothiochromenes with complete cis selectivity via intramolecular Prins-, aza-Prins-, and thia-Prins/Friedel-Crafts cyclizations, respectively. Though the Prins cyclization proceeds smoothly under the influence of Sc(OTf)(3), high conversions and enhanced reaction rates are achieved using a mixture of Sc(OTf)(3) and TsOH (1:3).
Journal of Organic Chemistry | 2009
Pierre Bannwarth; Alain Valleix; Danielle Grée; René Grée
Chiral pyrimidines with a fluorine atom in the benzylic position are easily accessible in high enantiomeric excesses from optically active propargylic intermediates by two complementary routes. Both the use of optically active propargylic fluorides and the fluorination of the chiral pyrimidine in the final stage give excellent results in terms of enantiocontrol. On the other hand, original pyrimidines with a difluoromethyl side chain are also obtained in a few steps from new propargylic ketones bearing a CHF(2) substituent on the triple bond.
Tetrahedron Letters | 2001
Christophe Crévisy; Marina Wietrich; Virginie Le Boulaire; Ramalinga Uma; René Grée
Allylic alcohols react with aldehydes, in the presence of catalytic amounts of Fe(CO)5 and under irradiation, to give mainly aldol products. A small amount of ketone resulting from the classical isomerization process is also isolated. This new aldol-type reaction is a complete atom economy process occurring under neutral conditions.
Synthetic Communications | 1985
Paul Mosset; René Grée
Abstract Sulfonium salts 1 and 3 are highly reactive epoxidizing agents under phase transfer catalytic conditions.
Journal of Organic Chemistry | 2010
Jillu S. Yadav; Prashant Borkar; P. Pawan Chakravarthy; Basi V. Subba Reddy; Akella V. S. Sarma; Shaik Jeelani Basha; Balasubramanian Sridhar; René Grée
Aryl epoxides undergo coupling smoothly with (E)-hex-3-ene-1,6-ditosylamide in the presence of 10 mol % p-TSA in 1,2-dichloroethane at 75 degrees C to produce the corresponding 1,5-ditosyl-octahydro-1H-pyrrolidino[3,2-c]pyridines in good yields with high trans-selectivity, whereas the coupling of (Z)-hex-3-ene-1,6-ditosylamide gave cis-fused octahydro-1H-pyrrolidino[3,2-c]pyridines predominantly. The use of readily available p-TSA makes this method simple, convenient, and practical.
Tetrahedron | 2001
Hassan Cherkaoui; Mohammed Soufiaoui; René Grée
Abstract The direct conversion of allylic alcohols to saturated carbonyls, using Fe(CO) 5 as a catalyst, offers good synthetic potential. Mono-, di- and even trisubstituted alkenes bearing various alkyl, aryl and electronwithdrawing groups on the allylic system give good to excellent yields of rearranged products. Limitations occur mainly with polyunsaturated derivatives. This reaction was applied to a short and efficient synthesis of cyclamen aldehyde and foliaver.
Chemical Communications | 2012
Prashant Borkar; Pierre van de Weghe; B. V. Subba Reddy; J. S. Yadav; René Grée
Novel synergistic effects between Lewis and Brønsted acids in Prins cyclization are reported. Non-reactive Lewis acids and non-reactive Brønsted acids, which failed to perform Prins cyclization when used alone, have shown remarkable synergistic effects when used in combination to perform the reaction successfully.