Jesús García López

Mechanisms of Stereomutation and Thermolysis of Spiro-1,2-oxaphosphetanes: New Insights into the Second Step of the Wittig Reaction

The experimentally observed stereomutation of spiro-1,2-oxaphosphetanes is shown by DFT calculations to proceed through successive M(B2) or M(B4) and M(B3) mechanisms involving two, four, and three Berry pseudorotations at phosphorus, respectively. Oxaphosphetane decomposition takes place in a single step via a polar transition state. The calculated activation parameters for this reaction are in good agreement with those determined experimentally.

Effect of genetic and phenotypic factors on the composition of commercial marmande type tomatoes studied through HRMAS NMR spectroscopy.

The effects of genetic, technological and environmental factors on the chemical composition of four marmande type tomato varieties have been investigated. The study is based on the analysis of (1)H HRMAS NMR spectra of tomato purée using a combination of partial least squares (PLS) and assigned signal analysis (ASA). In agreement with genetic, morphological and taste characteristics of the tomatoes studied, the analysis of the NMR data allows two groups of samples to be differentiated. The type of culture and climatic conditions can reduce the compositional differences. The extension of the compositional changes produced by climatic conditions is variety-depend. Neither grafting nor perlite affect significantly the relative content of primary metabolites. This was not the case for tomatoes grown using the pure hydroponic production system based on the recirculation of nutrient solution, New Growing System NGS®, which seems to be an effective agricultural approach to improve tomato quality.

Cα,Cortho-Dimetalated phosphazene complexes

The first C(alpha),C(ortho) dilithium complex of a phosphazene has been synthesized as a single stereoisomer and has been structurally characterized in solution; the complex is monomeric, with the dianion acting as an N-C(ortho) and O-C(alpha) chelate. Transmetallation with Me(3)SnCl and PhHgCl afforded the first C(alpha),C(ortho) homo- and hetero-bimetallic phosphazene complexes, which contain a desymmetrised Ph(2)PN moiety.