Reversibility and Enantioselectivity of Palladium-Catalyzed Allylic Aminations: Ligand, Base-Additive, and Solvent Effects.

The enantioselective, palladium-catalyzed reaction of benzylamine with ()-1,3-diphenylallyl ethyl carbonate was examined with 12 different chiral ligands across a range of scaffold types. In 8 out of 12 cases, the observed enantiomeric excess was 36-92% higher when DBU or CsCO was added. Nucleophile crossover experiments between the -benzyl-1,3-diphenylallylamine product and 4-methoxybenzylamine mechanistically linked the changes in enantioselectivity to reformation of the η-allylpalladium intermediate.

Incorporating Drought Thresholds Improves Model Predictions of Autumn Phenology in Tropical and Subtropical Forests.

Drought dramatically influences vegetation phenology, thereby impacting terrestrial carbon and water cycles. However, the mechanisms by which drought drives changes in autumn phenology remain unclear, hindering the accurate simulation of these processes in phenology models. In this study, we employed ridge regression analysis to quantify the dynamic effects of intensifying drought on the end-of-photosynthetic-growing-season (EOPS) and identified the drought threshold at which the vegetation's response to drought shifts.

Opioid Abuse: A Detailed Examination of Cost Drivers over a 24-Month Follow-up Period.

Background: Previous work has documented the considerable economic burden associated with opioid abuse, dependence, and overdose/poisoning (hereafter, "abuse"). Recent analyses have provided insights into the trajectory and drivers of the excess costs of abuse both before and after diagnosis, showing the important role of other substance abuse, mental health issues, and painful conditions.

Objective: To build on the recently published study by Kirson et al.

Drivers of excess costs of opioid abuse among a commercially insured population.

Objectives: To replicate and extend a recently published analysis of the drivers of excess costs of opioid abuse.

Study Design: Retrospective data analysis using de-identified claims data from the Truven MarketScan Commercial Claims and Encounter database.

Methods: Medical and prescription drug claims from beneficiaries covered by large self-insured US companies were used to select patients with incident diagnoses of opioid abuse between 2012 and 2015.