Elucidation of the structures of 3-alkylthio-, 3-benzylthio-, 2-arylthio- and 2-heteroarylthio-N1-(1,3-dimethylbutyl)-N4-phenyl-1,4-phenylenediamines by one- and two-dimensional NMR spectroscopy

Nucleophilic addition of alkyl- and benzylthiols to benzoquinone diimine (1) gave the corresponding 3-alkylthio- or 3-benzylthio-1,4-phenylenediamines (2-5). However, addition of aryl- or heteroarylthiols to 1 formed 2-arylthio- or 2-heteroarylthio-1,4-phenylenediamines (6-14). The structures of 2-14, obtained in 55-91% yields, were confirmed in CDCl3 or DMSO-d6 solution using 1D (NOE difference, coupled 13C NMR spectra, APT and DEPT) and 2D NMR techniques [DQCOSY, NOESY, HETCOR and heteronuclear multiple bond coherence (HMBC)] that resulted in unambiguous proton and carbon NMR resonance assignments. The substituent-induced 13C NMR chemical shift differences were calculated in 2-14 relative to carbon atoms in the model compound N1-(1,3-dimethylbutyl)-N4-phenyl-1,4-phenylenediamine (DMBPPD) (15) (a reduced form of benzoquinone diimine).     

A selected artificial intelligence bibliography for operations researchers

We have compiled a selected, classified, and annotated Artificial Intelligence bibliography specifically addressed to an operations research audience. The bibliography includes approximately 450 references from the areas of search (including heuristics and games), automatic deduction (including theorem proving, logic programming, and logical aspects of databases), planning, learning, and knowledge-based systems (with numerous specific applications to management, engineering, science, medicine, and other fields). We have also added a general references section, as well as a special section on Artificial Intelligence/Operations Research interfaces.Supported in part by Air Force through Grant AFOSR #0271.     

Viewing scheduling as an opportunistic problem-solving process

In a search for more efficient yet effective ways of solving combinatorially complex problems such as jobshop scheduling, we move towards opportunistic approaches that attempt to exploit the structure of a given problem. Rather than adhere to a single problem-solving plan, such approaches are characterized by almost continual surveillance of the current problem-solving state to possibly modify plans so that activity is consistently directed toward those actions that currently seem most promising. Opportunistic behavior may occur in problem decomposition down to selective application of scheduling heuristics. We developed and performed limited testing of a scheduling system, called OPIS 0, that exhibits such behavior to some extent. The results are encouraging when compared to ISIS and a dispatching system. It is believed that such opportunistic views of scheduling would lead to systems that allow more flexibility in terms of designing scheduling procedures and supporting the scheduling function.This research is sponsored in part by the Air Force Office of Scientific Research under Contract No. F49620-82-K-0017 and the Westinghouse Corporation.     

Novel syntheses of 2,3-dihydro-1,5-benzothiazepin-4(5h)-ones and 2h-1,4-benzothiazin-3(4h)-ones

Nucleophilic additions of alpha-mercaptoalkanoate esters and beta-mercaptoalkanoate acids to benzoquinone diimines, followed by cyclization with trifluoroacetic acid or 1,3-dicyclohexylcarbodiimide (DCC), provide novel, high-yielding syntheses of 2H-1,4-benzothiazin-3(4H)-ones (3a-f) and 2,3-dihydro-1,5-benzothiazepin-4(5H)-ones (5a-c), respectively.