No abstract

and acidified with hydrochloric acid (10%, 5 mL). A yellow precipitate of the dinitrobenzoate was removed by filtration and washed with aqueous sodium bicarbonate (10%, 5 mL). Recrystallization from cold carbon tetrachloride gave the 3,5-dinitrobenzoate as an amorphous golden yellow powder (0.29 g, 0.89 mmol, 82%): mp 127-128 °C (dec); NMR (CDC13) 3. 27-3.33

2-Methylthiobenzothiazole readily gives a methyl group lithio derivative which reacts cleanly with electrophiles. The products are conveniently converted into the corresponding thiols by BuLi at -78 "C, and this sequence thus provides a convenient two-step mercaptomethylation procedure for alkyl halides, aldehydes, and ketones.

No abstract

We discuss a knowledgddata centered architecture for CASE environments, that has at its heart a knowledge and data base management system (repository) on which all CASE tools rely for knowledge and data services. The repository has three entity kinds: objects, procedures, and rules.Data resides in the objects while knowledge resides in the procedures, rules, and special fields in the objects. We then discuss why a third generation DBMS, which incorporates data, object, and knowledge services, is a good choice for the knowledge manager.We use an object oriented model of software systems to analyze the storage requirements of program documents in the repository, and show how we use the procedures and rules to efficiently maintain multiple software document representations. We then show how the repository can effectively support a software reuse library, as well as reuse processes throughout the life-cycle. We conclude by outlining the future directions of our research.