Bench-stable 2-halopyridinium ketene hemiaminals as new reagents for the synthesis of 2-aminopyridines via mild nucleophilic aromatic substitutions with amine nucleophiles

Bench-stable N-(1-alkoxyvinyl) 2-halopyridinium triflates have been developed as reagents for the synthesis of valuable 2-aminopyridine scaffolds via unusually mild SNAr substitutions with amine nucleophiles. Advantages of this approach include an operationally simple mix-and-stir procedure at room temperature or mild heat, ambient atmosphere, and without need of transition metal catalysts, coupling reagents, and high-boiling solvents. The stable N-(1-ethoxyvinyl) moiety serves as a dual SNAr-activating group and pyridine N-protecting group that can be cleaved under thermal, acidic, or oxidative conditions. Preliminary results of nucleophilic aromatic substitutions using alcohol, thiol, indole, and silyl enol ether nucleophiles are also demonstrated

Global demand for natural resources eliminated more than 100,000 Bornean orangutans

Unsustainable exploitation of natural resources is increasingly affecting the highly biodiverse tropics. Although rapid developments in remote sensing technology have permitted more precise estimates of land-cover change over large spatial scales, our knowledge about the effects of these changes on wildlife is much more sparse. Here we use field survey data, predictive density distribution modeling, and remote sensing to investigate the impact of resource use and land-use changes on the density distribution of Bornean orangutans (Pongo pygmaeus). Our models indicate that between 1999 and 2015, half of the orangutan population was affected by logging, deforestation, or industrialized plantations. Although land clearance caused the most dramatic rates of decline, it accounted for only a small proportion of the total loss. A much larger number of orangutans were lost in selectively logged and primary forests, where rates of decline were less precipitous, but where far more orangutans are found. This suggests that further drivers, independent of land-use change, contribute to orangutan loss. This finding is consistent with studies reporting hunting as a major cause in orangutan decline. Our predictions of orangutan abundance loss across Borneo suggest that the population decreased by more than 100,000 individuals, corroborating recent estimates of decline. Practical solutions to prevent future orangutan decline can only be realized by addressing its complex causes in a holistic manner across political and societal sectors, such as in land-use planning, resource exploitation, infrastructure development, and education, and by increasing long-term sustainability

Effectiveness of 20 years of conservation investments in protecting orangutans

Conservation strategies are rarely systematically evaluated, which reduces transparency, hinders the cost-effective deployment of resources, and hides what works best in different contexts. Using data on the iconic and critically endangered orangutan (Pongo spp.), we developed a novel spatiotemporal framework for evaluating conservation investments. We show that around USD 1 billion was invested between 2000 and 2019 into orangutan conservation by governments, non-governmental organizations, companies and communities. Broken down by allocation to different conservation strategies, we find that habitat protection, patrolling and public outreach had the greatest return-on-investment for maintaining orangutan populations. Given variability in threats, land-use opportunity costs, and baseline remunerations in different regions, there were differential benefits-per-dollar invested across conservation activities and regions. We show that, while challenging from a data and analysis perspective, it is possible to fully understand the relationships between conservation investments and outcomes, and the external factors that influence these outcomes. Such analyses can provide improved guidance towards more effective biodiversity conservation. Insights into the spatiotemporal interplays between the costs and benefits driving effectiveness can inform decisions about the most suitable orangutan conservation strategies for halting population declines. While our study focuses on the three extant orangutan species of Sumatra and Borneo, our findings have broad application for evidence-based conservation science and practice worldwide