Teresa Mancilla

New bicyclic organylboronic esters derived from iminodiacetic acids

Abstract The reactions of phenylboronic acid or dinethylthexyboronic ester with iminodiacetic- or N -methyliminodiacetic acids lead to high yield to the air-stable bicyclic esters (N-B)phenyl[iminodiacete- O , N ]borane ( 1 ), (N-B)phenyl[ N -methyliminodiacetate- O , N ]borane ( 2 ), (N-B)thexy[iminodiacetate[ O , N ]borane ( 3 ) and (N-B)thexyl[ N -methyliminodiacetate- O , N ]borane ( 4 ). These are shown by 1 H, 11 B and 13 C NMR spectroscopy to have rigid bicyclic structures of strong intramolecular N-B coordination.

The NB coordination in hindered cyclic thexylboronic esters derived from diethanolamines

Abstract The reaction between thexylborane and diethanolamines in THF leads to cyclic thexylboronic esters. The intramolecular NB coordination was demonstraated by dynamic 1 H and 11 B NMR spectroscopy. The existence of steric interactions between the N-substituents of the B -thexyl group was indicated by the 1 H and 11 B NMR data.

NMR and X-ray diffraction studies of two bicyclic borates containing chiral boron and nitrogen atoms

Abstract Ring closure between the nitrogen and boron atoms during the syntheses of bicyclic organoboron compounds occurs under asymmetric induction, since reactions of optically active N-methyl-N-(1-methyl-2-phenyl-2-hydroxyethyl)glycines with 4-bromophenylboronic acid or with 1,4-phenylenediboronic acid provides the corresponding bicyclic boron derivatives (N → B)-4-bromophenyl[N-methyl-N- (1-(S)-methyl-2-(R)-phenyl-2-oxyethyl)aminoacetate-O,O′,N]boron (3a–3b), (N → B)-4-bromophenyl[N-methyl-N-(1-(S)-methyl-2-(S)-phenyl-2-oxyethyl)aminoacetate-O,O′,N]boron (4a–4b), (N → B)(N′ → B′)-1,4-phenylenebis[N-methyl- N-(1-(S)-methyl-2-(R)-phenyl-2-oxyethyl)aminoacetate-O,O′,N]bis-boron (5) and (N → B)(N′ → B′)-1,4-phenylenebis[N-methyl-N-(1-(S)-methyl-2-(S)-phenyl-2-oxyethyl)aminoacetate-O,O′,N]bisboron (6) in high stereochemical yields. The configuration of the nitrogen and boron atoms in 6 and in (N → B) phenyl[N-methyl-N-(1-(S)-phenyl-2-oxyethyl)aminoacetate-O,O′,N]boron (2) is established by single crystal X-ray diffraction studies.

ASYMMETRIC SYNTHESIS OF NEW BICYCLIC PHENYLBORONIC ESTERS CONTAINING CONFIGURATIONALLY STABLE CHIRAL NITROGEN AND BORON

Abstract The reaction between phenylboronic acid and N-alkyl-N-(ethyl-2-hydroxy)-aminoacetic acids leads stereoselectively to stable bicyclic esters containing chiral boron and nitrogen atoms.

Obtention de 3 types de derives du bore: esters aminoboriques tris n-boranes, esters amio boriques bis n-boranes et aminalcools n-boranes a partir de la reaction d'aminalcools-1,2 avec BH3.THF et BH3DMS. mise en evidence d'une coordination interner B←N

The reactions of 1,2-aminoalcohols with BH3.THF or DMS lead to various title compounds, depending on the reaction conditions. The structures have been determined using 11B, 1H nmr and i.r. spectroscopy and selected reactions. The conclusions differ from previous results: we were in particular able to evidence intramolecular N←B coordination in structures of type d and e.

X-ray analysis and structural characterization of 2-phenyl-6-aza-1,3- dioxa-2-borabenzocyclononenones

Nine new monomeric boronates of the type 2-phenyl-6-aza-1,3-dioxa-2-borabenzocyclononen-4-ones (3a � /3i) were prepared from N -(2-hydroxybenzyl)-a-aminoacids 1a � /1i and phenylboronic acid 2 using 20:1 benzene � /DMSO mixtures. The compounds were characterized by 1 H-, 13 C-, 11 B-, 15 N- and 2D-NMR (HETCOR, NOESY and COLOC) experiments, FT infrared, mass spectra and elemental analysis. Suitable monocrystals of cis -2-phenyl-6-aza-1,3-dioxa-2-borabenzocyclononen-4-one (3a), (2S ,5S ,6R )-2phenyl-6-aza-1,3-dioxa-5-sec butyl-2-borabenzocyclononen-4-one (3e) and 2,5-diphenyl-6-aza-1,3-dioxa-2-borabenzocyclononen-4one (3h) were obtained and their structures are discussed. The X-ray structures, as well as the NMR data established that the configurations at the nitrogen and boron atoms are ‘R ’ and ‘S ’, respectively and the transannular fusion is cis . A semi-empirical (SAM1) study allowed calculation of the energy for all possible stereoisomers, showing that the stabilization increases as the THC (TetraHedral Character of the boron atom) increases and also as the N 0/B bond distance decreases, in agreement with the experimental results. # 2002 Elsevier Science B.V. All rights reserved.

Synthesis and characterization of ethylphenylstannylene derivatives of ethylene glycol, cytidine and 3,5-diiodosalicylic acid

Abstract The synthesis and characterization of the ethylphenylstannylene derivatives of ethylene glycol, cytidine, and 3,5-diiodosalicylic acid are described.

Consequences stereochimiques de la fixation de BH3 sur la paire libre de l'azote des ephedrines:echange isotopique NH/ND stereospecifique.

Resume Six ephedrine borane derivatives were prepared. The fixation of nitrogen configuration in these compounds was demonstrated by observation of diastereotopic relationship for N-substituents or by formation of stable and isolated diastereoisomers. A stereospecific NH/ND exchange was observed for the N-H.

Syntheses of (N → B)phenyl[N-alkylaminodiacetate-O,O′,N]boranes

Abstract The syntheses of (N → B)phenyl[N-alkylaminodiacetate-O,O′,N]boranes (2 to 6) and their corresponding N-alkylaminodiacetic acids (7 to 10) are reported. All compounds (except 6) were characterized by 1H, 11B (for boron heterocycles). 13C NMR, infrared spectroscopy and mass spectrometry. The 1H NMR spectrum of compound 3 shows that it is a chiral molecule, its structure was determined by homonuclear decoupling experiments, 1H NMR and HETCOR. The study of the intramolecular N → B coordination by dynamic NMR afforded a Δ‡ value of 98.4 kJ mol−1 for compound 3.

Synthesis and in Vitro Antineoplastic Activity of Diorganostannylene Derivatives of 2,6-Pyridine Dicarboxylic Acid

The widespread success of platinum compounds in the clinical treatment of testicular and ovarian cancers for instance, has stimulated research in the area of metal-based anti-tumour drugs and spurred the search for organometallic compounds with improved therapeutic properties.