Ethyl 2-chlorooxazole-4-carboxylate: a versatile intermediate for the synthesis of substituted oxazoles

[reaction: see text] By using a sequence of regiocontrolled halogenation and palladium-catalyzed coupling reactions, the synthesis of variously substituted oxazoles from ethyl 2-chlorooxazole-4-carboxylate (2) was accomplished. The methodology was applied to the synthesis of a series of 2,4-disubstituted, 2,5-disubstituted, and 2,4,5-trisubstituted oxazoles.     

An approximate treatment of scattering based on the delta boundary operator

The development of a scheme to treat two-dimensional electromagneticscattering by electrically large, perfectly conducting bodiesis described. It incorporates the effects of surface curvatureand non-local phenomena and has the potential to provide thebasis for a general technique yielding more accurate predictionsthan the widely used physical optics method.     

Regiocontrolled synthesis of substituted thiazoles

The regiocontrolled synthesis of 2,5-disubstituted and 2,4,5-trisubstituted thiazoles from ethyl 2-bromo-5-chloro-4-thiazolecarboxylate 1 using sequential palladium-catalyzed coupling reactions is described. [reaction: see text]     

Cleavage or Acetyl-de-alkylation of 4-Methoxybenzyl (MPM) Ethers Using Acetic Acid

Aryl (4-methoxyphenyl)methyl (MPM) ethers are cleaved by heating with acetic acid for a few hours at 90°C, producing the corresponding phenols and (4-methoxyphenyl)methyl acetate. Under the same conditions alkyl MPM ethers are transformed directly into the corresponding alkyl acetates.     

Synthesis of 2-aryl-oxazolo[4,5-c]quinoline-4(5H)-ones and 2-aryl-thiazolo[4,5-c]quinoline-4(5H)-ones

[reaction: see text] Novel and highly efficient syntheses of oxazolo[4,5-c]quinoline-4(5H)-ones (1) and thiazolo[4,5-c]quinoline-4(5H)-ones (2) from ethyl 2-chlorooxazole-4-carboxylate (4) and ethyl 2-bromo-5-chlorothiazole-4-carboxylate (13), respectively, are described.     

A laboratory viscometer—gelation timer

During the past two decades, the information explosion has led to a demand for systems of storing and retrieving information in every branch of science and technology. A number of the larger abstracting services are already experimenting with systems covering so great an area that the use of a computer is essential.Since, however, the, field of rheology is relatively small a simple classification and retrieval system is being developed, for use inRheology Abstracts, based upon ordinary 132-hole edge-punched cards. The first half of the system deals with the rheology of fluids and is already in use; it is described in detail in a recent paper (1). The second half, dealing with the rheology of solids, is still being developed.In the fluids system, holes are punched to indicate the following essential features of a paper: general nature; language; type of fluid; rheological properties; type of flow; boundary conditions; important variables and effects; theoretical treatment; type of apparatus; industrial processes involved. As a result two simple hand operations will serve to retrieve, for example, all the papers concerned with turbulent flow of suspensions, or with fracture in polymer melts. Additional operations lead to a narrower, more precise, retrieval.At present the classifying is being done by abstractors. It is hoped that authors will become familiar with the system and will make a practice of classifying their own papers; this would lead to more accurate classification and to the benefit of all concerned.Paper presented at the Conference on Experimental Rheology, University of Bradford, April 17–19, 1968.     

Catalysis in flash vacuum pyrolysis

The temperature required for flash pyrolytic elimination of water from $\text{o}$-aminobenzyl alcohols and of carbon dioxide from dihydrobenzoxazinones to give azaxylylenes is considerably lowered by the presence of alumina and silica gel in the hot zone.