Synthesis of four cholic acid-based CSPs containing 2-naphthoyl carbamate and 3,5-dinitrophenylcarbamate moieties and their evaluation in the HPLC resolution of racemic compounds

A click chemistry approach to secosteroidal macrocycles

A new synthetic pathway towards secosteroidal macrocycles was described via a reaction of cycloaddition as the key step. The characteristic (1)H and (13)C NMR spectroscopic features of the synthesized compounds are reported.

Synthesis of various secosteroidal macrocycles by ring-closing metathesis

We set out to describe an efficient and versatile method for preparing secosteroidal macrocycles from cholic acid, via an oxidative ring-expansion/ring-opening sequence and a ring-closing metathesis reaction as the key steps. The characteristic ¹H and ¹³C NMR spectroscopic features of the synthesized compounds are reported.

Exhaustively substituted bile acids as chiral selectors for enantioselective chromatography

The use of chiral stationary phases (CSPs) obtained from cholic and deoxycholic acid derivatives in the HPLC resolution of racemic compounds is presented. The CSPs containing arylcarbamoyl derivatives of bile acids show enantiodiscriminating capabilities depending on the electronic character of the aryl substituents: the CSPs obtained starting from heteroderivatized selectors, i.e. bile acid derivatives containing both pi-acidic and pi-basic arylcarbamoyl moieties, show enantiodiscriminating capabilities strongly dependent on the arrangement of the electronically different arylcarbamates on the cholestanic backbone. The CSPs obtained starting from deoxycholic acid derivatives possessing both arylamido and arycarbamoyl substituents show enantiodiscriminating capabilities restricted to the resolution of benzodiazepine derivatives. Again, the enantioresolution properties depend not only on the electronic nature of the aromatic substituents but also on their arrangement on the cholestanic backbone. The comparison among the different families of bile acid based CSPs allows us to find likeness and differences in the enantiorecognition mechanism exhibited by the different chiral selectors.

Structural determinations by circular dichroism spectra analysis using coupled oscillator methods: An update of the applications of the DeVoe polarizability model

The exciton (coupled oscillator) model for optical activity is a very useful and powerful method which allows to analyze a circular dichroism (CD) spectrum in a nonempirical way, arriving at a safe assignment of the absolute configuration of organic and inorganic compounds. Usually in this model only the exciton coupling of two electrically allowed transitions (oscillators) is taken into account. This approach has the important advantage of an easy application but, sometimes, it may lead to wrong results. Thus, in this review article a more general treatment, which allows considering the simultaneous coupling of several oscillators, i.e., the DeVoe model, is presented and critically analyzed, discussing in detail the latest applications reported in the literature. In the authors opinion, since the DeVoe model joins generality and reliability requiring an almost negligible computational effort, it represents the method of choice for stereochemical assignments, even by nonspecialists.