Background: As the number of internet users increases, problems related to internet overuse are becoming more and more serious. Adolescents and youth may be particularly attracted to and preoccupied with various online activities. In this study, we investigated the relationship of internet addiction, smartphone addiction, and the risk of hikikomori, severe social withdrawal, in Japanese young adult. Methods: The subjects were 478 college/university students in Japan. They were requested to complete the study questionnaire, which consisted of questions about demographics, internet use, the Internet Addiction Test (IAT), the Smartphone Addiction Scale (SAS)–Short Version (SV), the 25-item Hikikomori Questionnaire (HQ-25), etc. We investigated the difference and correlation of the results between two groups based on the purpose of internet use or the total score of each self-rating scale, such as screened positive or negative for the risk of internet addiction, smartphone addiction, or hikikomori. Results: There was a trend that males favored gaming in their internet use while females used the internet mainly for social networking via smartphone, and the mean SAS-SV score was higher in females. Two-group comparisons between gamers and social media users, according to the main purpose of internet use, showed that gamers used the internet longer and had significantly higher mean IAT and HQ-25 scores. Regarding hikikomori trait, the subjects at high risk for hikikomori on HQ-25 had longer internet usage time and higher scores on both IAT and SAS-SV. Correlation analyses revealed that HQ-25 and IAT scores had a relatively strong relationship, although HQ-25 and SAS-SV had a moderately weak one. Discussion: Internet technology has changed our daily lives dramatically and altered the way we communicate as well. As social media applications are becoming more popular, users are connected more tightly to the internet and their time spent with others in the real world continues to decrease. Males often isolate themselves from the social community in order to engage in online gaming while females use the internet as to not be excluded from their communications online. Mental health providers should be aware of the seriousness of internet addictions and hikikomori.

Three-dimensional, small-ring scaffolds are very important in modern drug discovery to expand the available drug-like chemical space and to optimize drug candidates. Among them, bicyclo[1.1.1]pentane (BCP) is regarded as a high-value bioisostere for a phenyl ring or tert-butyl group; it provides an option to generate drug-like molecules with good passive permeability, high aqueous solubility, and improved metabolic stability, though the lack of methodology to functionalize BCP remains a significant challenge. Here we present an efficient method, developed with the aid of density functional theory calculations, for the synthesis of multifunctionalized BCP derivatives by means of a radical multicomponent carboamination of [1.1.1]propellane. This reaction features mild conditions, one-pot operation, and gram-scale synthetic capability, and opens up a unique and highly efficient route for the synthesis of multifunctionalized BCP derivatives, including synthetically useful 3-substituted BCP-amines.

Utilization of three-dimensional cyclic scaffolds is important in modern drug discovery, both to provide greater opportunities for optimizing drug candidates and to expand the available chemical space of drugs. Among these scaffolds, bicyclo[1.1.1]pentane (BCP) is a high-value bioisostere for 1,4-disubstituted phenyl rings, internal alkynes, and the tert-butyl group, generally offering high passive permeability, high water solubility, and improved metabolic stability. However, the lack of methods for functionalizing BCP remains a significant challenge, and in particular, a versatile strategy for synthesizing a wide range of unsymmetrically 1,3-difunctionalized BCP derivatives has been lacking. In this account, we review recent advances in the synthetic chemistry of BCP, focusing especially on our recently developed radical multicomponent carboamination of [1.1.1]propellane.1 Introduction2 Overview of the Synthetic Chemistry of [1.1.1]Propellane, the Most Promising Precursor of Bicyclo[1.1.1]pentane3 Recent Advances in the Synthetic Chemistry of Unsymmetrically 1,3-Disubstituted Bicyclo[1.1.1]pentane Derivatives4 Radical Multicomponent Carboamination of [1.1.1]Propellane Permits Direct Synthesis of 3-Substituted Bicyclo[1.1.1]pent-1-ylamine Derivatives5 Conclusion

The silaboration of [1.