α-Hydroxy ketones as masked ester donors in Brønsted base catalyzed conjugate additions to nitroalkenes

Abstract

The catalyst-controlled enantioselective direct addition reaction of enolizable esters and related carboxylic acid derivatives to p electrophiles remains a difficult synthetic transformation. In this study, the suitability of a-hydroxy ketones as ester equivalents capable of being activated by bifunctional Brønsted base catalysts in the context of conjugate addition reactions to nitroolefins is demonstrated. The scope of the reaction, which affords the corresponding Michael adducts with very high stereoselectivity (diastereomeric ratio (d.r.) +95:5, up to 99% enantiomeric excess (ee)), and its limitations are explored, as is the aftermath elaboration of adducts into densely functionalized enantioenriched products.

There is now growing evidence that parkinsonism and other extrapyramidal signs are highly prevalent in patients with first-episode psychosis who have never been exposed to antipsychotic drugs. However, the neurocognitive correlates of parkinsonism in this population remained to be clarified. A sample comprising 100 consecutive drug-naive patients with first-episode psychosis were enrolled on the study and followed up for 6 months. Seventy-seven completed assessments at 3 time points (baseline, 1 mo, and 6 mo), involving clinical and cognitive examinations and a specific assessment of motor abnormalities. The Simpson-Angus Scale (SAS) was used for the assessment of extrapyramidal signs, and each motor domain was evaluated with a standard assessment scale. Linear mixed models were built to explore the longitudinal relationships between parkinsonism scores and cognitive impairment. Parkinsonism scores showed significant strong longitudinal associations with deficits in memory, executive functioning, and attention. Spontaneous parkinsonism (total SAS score and hypokinesia and rigidity subscores at baseline) showed high 6-month predictive values for cognitive impairment. In addition, they also had high predictive values for neurologic soft-sign abnormalities but not for dyskinesia, akathisia, and pure catatonic abnormalities. No predictive value was found for glabella-salivation or tremor subscores on the SAS scale. These results emphasize the relevance of the assessment of parkinsonism signs prior to starting to administer antipsychotic drugs, as core manifestations of psychotic illness with a high predictive value for cognitive impairment.