0000000001309080
AUTHOR
E. Falomir
showing 13 related works from this author
Double Diastereoselection in Aldol Reactions Mediated by Dicyclohexylchloroborane between Chiral Aldehydes and a Chiral Ethyl Ketone Derived from l-E…
2005
Both matched and mismatched diastereoselections have been observed in the aldol reactions of a range of chiral aldehydes with the dicyclohexylboron enolate of a chiral ethyl ketone related to l-erythrulose. As was previously observed in the corresponding aldol reactions with l-erythrulose derivatives, the Felkin−Anh model provides an adequate explanation for the stereochemical outcome of reactions with chiral α-methyl aldehydes. However, a satisfactory account of the results observed with α-oxygenated aldehydes was only possible with the Cornforth model. As a practical application of the methodology described herein, a C1−C9 fragment of the structure of the antifungal macrolide soraphen A1α…
Stereoselective Total Synthesis and Absolute Configuration of the Natural Decanolides (−)-Microcarpalide and (+)-Lethaloxin. Identity of (+)-Lethalox…
2005
[reaction: see text] Convergent, stereoselective syntheses of the pharmacologically active, naturally occurring lactones (-)-microcarpalide and (+)-lethaloxin have been achieved from the commercially available, chiral reagents (R)-glycidol, (S,S)-tartaric acid, and d-ribose as the starting materials. These syntheses have further served to establish the hitherto unknown absolute configuration of (+)-lethaloxin and to show its identity with (+)-pinolidoxin.
2.14 Selected Diastereoselective Reactions: Enolate Alkylation
2012
This chapter discusses processes in which enolates are subjected to reaction with alkylating reagents. In all the processes examined here, at least one of the two reaction components is chiral and the reaction gives rise to one or more diastereomeric compounds. In most cases, the enolate is generated through deprotonation of the corresponding carbonyl precursor with a suitable base, but in several cases, the enolate is generated differently, for example, through Michael addition of a nucleophile to a conjugated carbonyl compound. The various factors that have been found to influence the stereochemical outcome of the alkylation reaction in a measurable way are also discussed. The material ha…
An ab initio study of the enolboration of 3-pentanone mediated by boron monochlorides L2BCl
2001
Abstract Using ab initio methods at the HF/6-31G∗∗ level, we have studied the mechanism of the enolboration of 3-pentanone mediated by boron monochlorides L2BCl (L=H, methyl and isopropyl) and trimethyl amine. The size of the L group has been found to have a decisive influence on the configuration (E or Z) of the formed boron enolate. Thus, whereas our calculations predict that dimethylboron chloride yields the Z enolate with high stereoselectivity, diisopropylboron chloride is found to yield predominantly the E enolate. The difference in behavior is due mainly to steric features related to the conformational bias of the respective ketone–boron chloride complexes formed reversibly in the fi…
Stereoselective anti aldol reactions of erythrulose derivatives. Functionalized chiral d3 and d4 synthons.
2004
An improved procedure for the synthesis of anti aldols from protected erythrulose derivatives is reported. The preparation of functionalized d3 and d4 synthons with various stereochemical arrays by means of this methodology is described and subsequently applied to a stereoselective formal synthesis of the natural metabolite goniothalesdiol.
Double diastereoselection in aldol reactions mediated by dicyclohexylchloroborane between L-erythrulose derivatives and chiral aldehydes. The Felkin-…
2003
Both matched and mismatched diastereoselections have been observed in aldol reactions of the B,B-dicyclohexylboron enolate of a protected l-erythrulose derivative with a range of chiral aldehydes. The stereochemical outcome of reactions with alpha-methyl aldehydes can be adequately explained within the Felkin-Anh paradigm. In the case of alpha-oxygenated aldehydes, however, strict adherence to this model does not allow for a satisfactory account of the observed results. In such cases, the Cornforth model provides a much better explanation.
Chlorodicyclohexylborane-mediated aldol additions of alpha,alpha'-dioxygenated ketones.
2001
Boron aldol additions of variously O-protected alpha,alpha'-dioxygenated ketones using dicyclohexylboron chloride and a tertiary amine have been investigated. The stereoselectivity of the process was dependent on the protecting group on the alpha-oxygen atoms. Notably, ketones with bulky silyloxy groups gave syn aldols, most likely via Z enolates. This rules out the participation of chelates during the enolization process, at least in the presence of such sterically crowded protecting groups. An alternative explanation is offered.
Stereoselective Synthesis of the Glycosidase Inhibitor Australine through a One-Pot, Double-Cyclization Strategy
2006
[reaction: see text] A stereocontrolled, convergent synthesis of the alkaloid australine, a glycosidase inhibitor of the pyrrolizidine class, is described. The chiral starting materials were ketone 3, derived from L-erythrulose, and alpha-alkoxy aldehyde 4, prepared from L-malic acid. A key step of the synthesis was the highly stereoselective aldol reaction between 4 and a Z boron enolate derived from 3. Another key step was the one-pot construction of the bicyclic pyrrolizidine system by means of a three-step sequence of SN2 displacements induced by benzylamine on a trimesylate precursor.
CCDC 271535: Experimental Crystal Structure Determination
2006
Related Article: J.Garcia-Fortanet, J.Murga, E.Falomir, M.Carda, J.A.Marco|2005|J.Org.Chem.|70|9822|doi:10.1021/jo051353p
CCDC 210749: Experimental Crystal Structure Determination
2004
Related Article: J.A.Marco, M.Carda, S.Diaz-Oltra, J.Murga, E.Falomir, H.Roeper|2003|J.Org.Chem.|68|8577|doi:10.1021/jo035159j
CCDC 269222: Experimental Crystal Structure Determination
2006
Related Article: S.Diaz-Oltra, J.Murga, E.Falomir, M.Carda, G.Peris, J.A.Marco|2005|J.Org.Chem.|70|8130|doi:10.1021/jo051307p
CCDC 269772: Experimental Crystal Structure Determination
2006
Related Article: S.Diaz-Oltra, J.Murga, E.Falomir, M.Carda, G.Peris, J.A.Marco|2005|J.Org.Chem.|70|8130|doi:10.1021/jo051307p
CCDC 223372: Experimental Crystal Structure Determination
2004
Related Article: J.Murga, P.Ruiz, E.Falomir, M.Carda, G.Peris, J.A.Marco|2004|J.Org.Chem.|69|1987|doi:10.1021/jo0356356