Fused ring materials

Few appHcations for fluoronaphthalenes and related polycycHc stmctures have materialized. The fused-ring bicycHc, suHndac [38194-50-2] a monofluorinated indene-3-acetic acid, is used as an antiinflammatory agent. 

Pyrazoles, Indazoles, and their Derivatives as Starting Materials for the Syntheses of Fused Ring Systems... 

A general strategy towards praziquantel derivatives 217 was developed by Liu et al. based on an Ugi four-component condensation (Ugi-4CR) followed by a Pictet-Spengler cyclization (PS-2CR) [66]. The variations of the groups and sub-stitutents in these scaffolds arise from the four starting materials isocyanide 218, aldehyde 219, amine 214, and carboxylic acid 220 (Scheme 39). This process produces ketopiperazine fused ring systems that mimic the scaffold of praziquantel. 

This chapter covers literature published since 1982 early materials are included here only where needed as a basis for describing further developments or where not previously mentioned in CHEC-1 <84CHEC-l(5)669>. The structural types surveyed here include 1,2,3-triazoles, benzotriazoles, their dihydro derivatives and carbocyclic fused compounds. Compounds with heterocyclic fused rings are not included. The nomenclature system was discussed in CHEC-T <84CHEC-I(5)670>. 

Since the publication of CHEC-II(1996), there have been very few examples related to the reactivity of substituents attached to ring carbon atoms. One case involves the reaction of 3-benzylidene-2,3-dihydro-2-methyl-l,2-benzothiazin-4-one 1,1-dioxide 163 with the alkylidenephosphorane derived from salt 164 forming the tricyclic-fused ring compound 165 (Scheme 20) <1996J(P1)2541>. This material 165 was oxidized with 2,3-dichloro-5,6-dicyano-l,4-benzoquinone (DDQ) affording the biphenyl 166. Ring-opened product 167 was produced from 165 upon exposure to />-toluene-sulfonic acid and heat. 

Two pyridopyrazine-fused heterocycles can be presented here, having either a [2,3- ] or a [3,4- ] junction more work has been published on the first type than on the second one. o-Diaminopyridine derivatives are the main starting materials used for constructing such fused ring systems by condensation with a-dicarbonyl compounds. 

Fluoranthene (Called 1,2-benzo-acenaphthy-len or 1,8-o-phenylen-naphthylen in Ger), C16H10(Thought to be ClaH10in early literature), mw 202.24, colorless ndls, sp gr 1.158 at 20°, nD 1.739 at 20°, bp 393°, 217°(30mm Hg), mp 109.5-110.5°, sol In benz, chlf, eth, HAc hot ale. A tetracyclic fused ring aromatic hydrocarbon, this material is found in some coal tars. It forms definite complexes with many poly nitrated aromatics (Refs 1 to 6) Refs 1) Beil 5, 685, (340, 344), [609] 2276 2) J. vonBraun E. Anton, Ber... 

The conversion of DAMN into 2,3-dicyanopyrazines substituted in the 5-and 6-positions with various combinations of amino, cyano, chloro, and hydroxyl groups will be described in this section along with transformations of these initially formed materials into a variety of other multifunctional and fused ring pyrazines. 

Material in this chapter is arranged firstly by the number of heteroatoms in the heterocyclic ring, secondly by the orientation of the heteroatoms to the fused ring (usually benzenoid), and finally by the size of the heterocyclic ring. 

The arrangement of the material in this chapter follows closely that for the bicyclic analogues it is ordered first by the mutual relationship of the fused rings, second by the number of heteroatoms and finally by the size of the heterocyclic ring. We define adjacent as in (1) and non-adjacent fused rings as in (2). Rings of type (3) form a class of pen -annulated heterocyclic systems which are of growing importance. 

Recently, a joint effort of material Laboratory at Wright Research and Development Center and Photonics Research Laboratory at SUNY at Buffalo has resulted in a comprehensive study of structure-nonlinear optical properties of a large number of systematically varied aromatic heterocyclic compounds involving fused ring benzimidazole and benzthiazole structures (10,30). 

Benzene is a volatile, colorless, highly flammable liquid that is consumed as a raw material for the manufacture of phenolic and polyester resins, polystyrene plastics, alkylbenzene surfactants, chlorobenzenes, insecticides, and dyes. It is hazardous both for its ignitability and toxicity (exposure to benzene causes blood abnormalities that may develop into leukemia). Naphthalene is the simplest member of a large number of multicychc aromatic hydrocarbons having two or more fused rings. It is a volatile white crystalline solid with a characteristic odor and has been used to make mothballs. The most important of the many chemical derivatives made from naphthalene is phthalic anhydride, from which phthalate ester plasticizers are synthesized. 

This procedure illustrates formylation by N,N-dimethylamino-methoxymethylium methyl sulfate, a compound which can be produced readily by reaction of easily available materials. 6-(Dimethylamino)fulvene is a useful intermediate for the synthesis of various fused-ring nonbenzenoid aromatic compounds. 

The Diels-Alder reaction between (2 ,4Z)-hexa-2,4-diene with the dieno-phile 2-methoxycyclohexa-2,5-diene- 1,4-dione yields four stereoisomers. The Diels-Alder reaction is a stereospecific reaction, therefore the configuration of both the starting materials is relocated in the product. Since the reaction is a concerted [4 + 2] cycloaddition, all the products here have always cis-fused rings and because the configuration of (2 ,4Z)-hexa-2,4-diene remains unaltered, both methyl groups in the product will be trans to each other. The various stereoisomers result because the diene and the dienophile may approach each other from both sides and in two distinct orientations. Note that the reaction occurs almost exclusively at the electron poor double bond of the dienophile. In order to deduce the relationships the... 

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