Papers by Cristina Aragoncillo
Tetrahedron Letters, Oct 1, 1999
Pyrazole derivatives Pyrazole derivatives R 0180 Asymmetric Synthesis of Densely Functionalized P... more Pyrazole derivatives Pyrazole derivatives R 0180 Asymmetric Synthesis of Densely Functionalized Pyrazolidines and 1,3-Diamines.-Condensation of chiral cyclic carbazate (I) with aldehydes such as (II) followed by reaction with 1,2-disubstituted alkenes (IV) and (VI) via a cycloreversion-cycloaddition process yields highly functionalized bicyclic pyrazolidines such as (V) and (VII). These products [cf. (V)] can be transformed to a variety of optically active products including polysubstituted 1,3-diamines (XI).
ChemInform, Apr 28, 2011
Expeditious Entry to Enantiopure Mono-and Bis(tricyclic) β-Lactams by Single or Double [2 + 2] Cy... more Expeditious Entry to Enantiopure Mono-and Bis(tricyclic) β-Lactams by Single or Double [2 + 2] Cycloaddition of Allenynes.-Thermal cycloaddition of β-lactam-tethered allenynes, e.g. (III), provides access to structurally novel tricyclic β-lactams containing a seven-membered ring and a strained cyclobutene ring. The reaction can be extended to bis(allenynes) to give symmetrical (X) or unsymmetrical bis(cycloadducts) (XIV). A reaction mechanism involving a tetraradical intermediate is proposed.-(ALCAIDE*, B.;
ChemInform, Jan 13, 2009
Indium-Promoted Acyloxyallylation Reaction of Azetidine-2,3-diones in Aqueous Media: A New Route ... more Indium-Promoted Acyloxyallylation Reaction of Azetidine-2,3-diones in Aqueous Media: A New Route to Densely Functionalized 3-Substituted 3-Hydroxy-β-lactams.-Under indium-promoted Barbier conditions, 2 stereocenters are formed: the stereochemistry at the new C-3 quaternary center is fully controlled by placing a bulky chiral substituent at C-4. However, poor stereoselectivities depending on the nature of the N-protecting group are observed at the new allylic stereocenter.-(ALCAIDE*,
Topics in heterocyclic chemistry, 2015
The skeleton of β-lactams and β-lactones is present in biologically active compounds. For example... more The skeleton of β-lactams and β-lactones is present in biologically active compounds. For example, the β-lactam ring is present in classical antibiotics such as penicillins and cephalosporins. On the other hand, there are several natural products containing a β-lactone moiety, with interesting inhibitory activity. In addition, both fragments are very useful synthetic intermediates for the preparation of cyclic and acyclic compounds. The ring strain present in both motifs is involved in this versatile reactivity. This chapter is devoted to the synthesis of five- to seven-membered heterocycles by ring expansion of β-lactams and β-lactones. Different methodologies have been described, and the mechanism for the formation of the products has been discussed. In addition, the applicability of some of the processes has been demonstrated by the synthesis of fragments of natural or biologically relevant compounds. The contributions presented in this chapter have been selected mainly from the developments achieved in the last decade.
ChemInform, Feb 12, 2008
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was e... more ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform, Jun 3, 2010
ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was e... more ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform, May 19, 2010
ABSTRACT For Abstract see ChemInform Abstract in Full Text.
Journal of Organic Chemistry, Jan 13, 2004
ChemInform, May 23, 2010
Metal-Promoted Allylation, Propargylation, or Allenylation of Azetidine-2,3-diones in Aqueous and... more Metal-Promoted Allylation, Propargylation, or Allenylation of Azetidine-2,3-diones in Aqueous and Anhydrous Media. Application to the Asymmetric Synthesis of Densely Functionalized 3-Substituted 3-Hydroxy-β-lactams.-The title reactions offer a convenient asymmetric approach to potentially bioactive 3-substituted 3-hydroxy-β-lactams. The stereochemistry is controlled by the chiral auxiliary at C-4. The regioselective outcome of the coupling with alkynes depends on the nature of metal promoter and solvent used as well as on steric effects.-(ALCAIDE, BENITO; AL
ChemInform, Feb 24, 2004
Table of Contents General Procedure for the Preparation of Tricyclic β-Lactams 3 and 5 S1 Charact... more Table of Contents General Procedure for the Preparation of Tricyclic β-Lactams 3 and 5 S1 Characterization of Tricyclic β-Lactam (+)-3b S2 Characterization of Tricyclic β-Lactam (+)-3c S2 Characterization of Tricyclic β-Lactam (±)-5a S2 General Procedure for the Preparation of Vinylic Stannanes 6 S2 Characterization of Bicyclic β-Lactam (-)-6a S3 Characterization of Bicyclic β-Lactam (±)-6c S3 General Procedure for the Preparation of Tricyclic β-Lactams 3 and 5. A solution of the corresponding enallene 2 (0.20 mmol) in toluene (10 mL) was heated in a sealed tube at 220 o C until disappearance of the starting material (TLC). The reaction mixture was allowed to cool to
ChemInform, Jun 12, 2014
Cyclization Reactions of Hydrazones. Part 24. Synthesis of 2-Aryl[1]benzofuro[2,3-e][1,2,4]triazi... more Cyclization Reactions of Hydrazones. Part 24. Synthesis of 2-Aryl[1]benzofuro[2,3-e][1,2,4]triazin-3(2H)-ones and Their Use for Preparation of 1-Aryl-5-(2-hydroxyphenyl)-6-azauracils.-Thermal cyclization of readily available arylhydrazones (III) provides the title benzofurotriazinones (IV) (9 examples), derivatives of a new heterocyclic ring system, which undergo hydrolytic splitting furnishing the azauracil derivatives (V).-(STYSKALA,
ChemInform, Jun 11, 2010
ABSTRACT
ChemInform, Nov 21, 2013
ABSTRACT An efficient method for the one-step conversion of beta-lactams to their corresponding f... more ABSTRACT An efficient method for the one-step conversion of beta-lactams to their corresponding functionalized azetidines has been developed. This approach takes advantage of the selective reduction of the 2-azetidinone nucleus with hydrosilanes in the presence of a zinc-based catalyst. The methodology is tolerant towards sensitive groups such as allene, ester, and cyanohydrin moieties. In addition, the process allows the preparation of enantiopure azetidines without erosion of the stereochemical integrity. A catalytic cycle involving an azetidinium salt intermediate has been proposed.
ChemInform, Oct 14, 2003
ABSTRACT
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
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Papers by Cristina Aragoncillo