An efficient, mild, metal-free, base-mediated intramolecular cyclization of N-alkyl, N-propargylic β-enaminones has been realized for the generation of polysubstituted pyrrole derivatives.
A convenient base-mediated strategy to synthesize 3-aryol-4-methyl (or benzyl)-2-methylthio furans 2 (trisubstituted furans) has been developed through the domino coupling/annulations between available α-oxo ketene dithioacetals 1 and propargyl alcohols. In this strategy, these types of bases play an important role in driving the domino coupling reaction of propargyl alcohols and further intramolecular annulations to realize the target compounds. The possible mechanism for the formation of the various products is believed to involve the generation of allenes 7, followed by intramolecular annulations.
With the rapid development of GPS enabled devices (smartphones) and location-based applications, location privacy is increasingly concerned. Intuitively, it is widely believed that location privacy can be preserved by publishing aggregated mobility data, such as the number of users in an area at some time. However, a recent attack shows that these aggregated mobility data can be exploited to recover individual trajectories. In this paper, we first propose two differentially private basic schemes for aggregated mobility data publication, namely direct perturbation and threshold perturbation, which preserve location privacy of users and especially resist the trajectory recovery attack. Then, we explore the moving characteristics of mobile users, and design an improved scheme named static hybrid perturbation by combining the two basic schemes according to the moving characteristics. Since static hybrid perturbation works only for static data, which are entirely available before publishing, we further adapt the static hybrid perturbation by combining it with linear regression, and yield another improved scheme named dynamic hybrid perturbation. The dynamic hybrid perturbation works also for dynamic data, which are generated on the fly during publication. Privacy analysis shows that the proposed schemes achieve differential privacy. Extensive experiments on both simulated and real datasets demonstrate that all proposed schemes resist the trajectory recovery attack well, and the improved schemes significantly outperform the basic schemes.
CCS CONCEPTS• Security and privacy → Privacy protections;
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.