Moisés Romero-Ortega

Synthesis of the C10-C17 fragment of aurisides and callipeltosides

Abstract The key unsaturated chiral C10–C17 fragment common on the synthesis of aurisides and callipeltosides was synthesized in six steps from 5-bromopentadienal via aldol condensation with Nagaos chiral auxiliary and further manipulation using Ohiras reagent and Negishis carboalumination–iodination.

Chemoselective aromatic C-H insertion of α-diazo-β-ketoesters catalyzed by dirhodium(II) carboxylates.

The ability of α-diazo-β-ketoesters bearing a substituent on the benzylic position to undergo aromatic C-H insertion is described. Good to excellent yields of the aromatic C-H insertion products were observed with Rh(2)(tpa)(4) or Rh(2)(esp)(2) catalysts. This is an attractive strategy to prepare tetralins carrying a methyl group on the benzylic position, a structural motif found in several types of natural products.

A Short Synthesis of (±)‐Sporochnol A, A Chemical Fish Deterrent from a Caribbean Marine Alga

Abstract A short formal synthesis of (±)‐sporochnol A (1) is described. In this synthesis, the quaternary carbon center is formed by successive alkylations of the carbanion α to the nitrile in an arylacetonitrile derivative, followed by conversion of the nitrile group to a vinyl group. The quaternary carbon center derivatives obtained in each step were characterized by spectroscopy.

Reactivity of electrophilic chlorine atoms due to σ-holes: a mechanistic assessment of the chemical reduction of a trichloromethyl group by sulfur nucleophiles

σ-Holes are shown to promote the electrophilic behavior of chlorine atoms in a trichloromethyl group when bound to an electron-withdrawing moiety. A halogen bond-type non-covalent interaction between a chlorine atom and a negatively charged sulfur atom takes place, causing the abstraction of such a chlorine atom while leaving a carbanion, subsequently driving the chemical reduction of the trichloromethyl group to a sulfide in a stepwise process. The mechanism for the model reaction of trichloromethyl pyrimidine 1 with thiophenolate and thiophenol to yield phenylsulfide 4 was followed through 1H-NMR and studied using DFT transition state calculations, and the energy profile for this transformation is fully discussed. MP2 calculations of the electrostatic potential were performed for a series of trichloromethyl compounds in order to assess the presence of σ-holes and quantify them by means of the maximum surface electrostatic potential. Such calculations showed that the chlorine atoms behave as electrophilic leaving groups toward a nucleophilic attack, opening a new possibility in the synthetic chemistry of the trichloromethyl group.