Modern database applications are among the most widely used and complex software systems. They constantly evolve, responding to changes to data, database schemas, and code. It is challenging to manage these changes and ensure that everything co-evolves consistently. For example, when a database schema is modified, all the code that interacts with the database must be changed accordingly. Although database evolution and software evolution have been extensively studied in isolation, the co-evolution of schema and code has largely been unexplored.This paper presents the first comprehensive empirical analysis of the co-evolution of database schemas and code in ten popular large open-source database applications, totaling over 160K revisions. Our major findings include: 1) Database schemas evolve frequently during the application lifecycle, exhibiting a variety of change types with similar distributions across the studied applications; 2) Overall, schema changes induce significant code-level modifications, while certain change types have more impact on code than others; and 3) Co-change analyses can be viable to automate or assist with database application evolution. We have also observed that: 1) 80% of the schema changes happened in 20-30% of the tables, while nearly 40% of the tables did not change; and 2) Referential integrity constraints and stored procedures are rarely used in our studied subjects. We believe that our study reveals new insights into how database applications evolve and useful guidelines for designing assistive tools to aid their evolution.

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An aryne 1,2,3-trisubstitution with aryl allyl sulfoxides is accomplished, featuring an incorporation of C-S, C-O, and C-C bonds on the consecutive positions of a benzene ring. The reaction condition is mild with broad substrate scope. Preliminary mechanistic study suggests a cascade formal [2 + 2] reaction of aryne with S═O bond, an allyl S → O migration, and a Claisen rearrangement.

An aryne precursor with a potential to perform domino aryne chemistry was proposed and synthesized. The reaction of this reagent with benzothioamide derivatives could afford 2,4-disubstituted benzothiazole with sequential incorporation of C-S, C-N, and C-C bonds on the consecutive three positions of the aryne precursor.

Metrics & MoreArticle Recommendations CONSPECTUS: Polysubstituted arenes are prevalent in numerous natural products, medicines, agrochemicals, and organic functional materials. Among methods to prepare polysubstituted arenes, pathways involving benzyne intermediates are particularly attractive given they can readily assemble highly diverse vicinal difunctionalized benzenes in a step-economical manner under transition-metal-free conditions. In order to incorporate more than two substituents on a benzene ring via a benzyne intermediate, methodologies involving benzdiyne and benztriyne have been developed, which significantly expand the current difunctionalization strategies in benzyne chemistry.In the past years, our group has been focusing on pushing the frontier of traditional benzyne chemistry and exploring new applications. In an aim to efficiently and conveniently construct polysubstituted arenes, we developed several aryne multifunctionalization strategies. The first strategy is through the 1,2benzdiyne processes, which can be divided into a domino aryne approach and stepwise 1,2-benzdiyne approach. In our domino aryne study, we developed three domino aryne reagents as "sesquibenzyne" synthons, which are complementary in terms of reactivity and could adapt different modes of cascade transformations. By employing these domino aryne precursors, we were able to accomplish several cascade transformations, including double nucleophilic reactions, i.e., the reaction with carbonyl protected benzothioamides, 1,2-diamination, and 1,3-diamination. In addition, two cascade processes involving nucleophilic and pericyclic reactions, namely, domino aryne annulation via nucleophilic-ene cascade and domino aryne nucleophilic, Diels−Alder process, were successfully achieved as well. Meanwhile, with our desire to expand the scope of 1,2-benzdiyne transformations, we employed stepwise 1,2-benzdiyne tactics to access polysubstituted arenes. Depending on the property of the substituent on the C3-position of a benzyne intermediate, either an electron-withdrawing or electron-donating group, the incoming ortho groups were chosen accordingly. Consequently, we realized a [2 + 2] cycloaddition-Grob fragmentation process using 3-triflyloxybenzyne and a 1,2benzdiyne process using 3-(trimethylsilyl)benzyne.Our second research strategy is to use single benzyne to access trisubstituted arenes, which represents a more atom-and stepeconomical protocol. With our deliberate design, we discovered a tandem benzyne SO bond insertion/C−H functionalization process using single benzyne and aryl allyl sulfoxides, furnishing three chemical bonds of different types in a single process. This transformation is the first 1,2,3-trisubstitution example using single benzyne intermediate. At last, we developed an oxidative dearomatization strategy on Kobayashi benzyne precursors, which led to the preparation of various cyclohexenynone precursors with diverse substituents in highly efficient manner. In this study, we also demonstrated a new reaction mode of th...