Ring-substituted derivatives

A-4-Thiazoline-2-ones and ring substituted derivatives are usually prepared by the general ring-closure methods described in Chapter II. Some special methods where the thiazole ring is already formed have been used, however. An original synthesis of 4- 2-carboxyphenyl)-A-4-thiazoline-2-one (18) starting from 2-thiocyanato-2-halophenyl-l-3-indandione (19) has been proposed (Scheme 8) (20, 21). Reaction of bicyclic quaternary salts (20) may provide 3-substituted A-4-thiazoline-2-one derivatives (21) (Scheme 9) (22). Sykes et al. (23) report the formation of A-4-thiazoline-2-ones (24) by treatment ef 2-bromo (22) or 2-dimethylaminothiazole (23) quaternary salts with base (Scheme 10). 

Ring-Substituted Derivatives The ring-chlorinated derivatives of benzyl chloride, benzal chloride, and benzotrichloride are produced by the direct side-chain chlorination of the corresponding chlorinated toluenes or by one of several indirect routes if the required chlorotoluene is not readily available. Physical constants of the main ring-chlorinated derivatives of benzyl chloride, benzal chloride, and benzotrichloride are given in Table 4. 

The drugs 3,4-methylenedioxymethamphetamine (MDMA) and 3,4-methyl-enedioxyamphetamine (MDA) are ring-substituted derivatives of methamphetamine and amphetamine, respectively. These methylenedioxy-substituted amphetamines have been reported to exhibit both stimulant and psychotomimetic properties (Anderson et al. 1978 Braun et al. 1980 ... 

Pd(OAc)2 works well with strained double bonds as well as with styrene and its ring-substituted derivatives. Basic substituents cannot be tolerated, however, as the failures with 4-(dimethylamino)styrene, 4-vinylpyridine and 1 -vinylimidazole show. In contrast to Rh2(OAc)4, Pd(OAe)2 causes preferential cyclopropanation of the terminal or less hindered double bond in intermolecular competition experiments. These facts are in agreement with a mechanism in which olefin coordination to the metal is a determining factor but the reluctance or complete failure of Pd(II)-diene complexes to react with diazoesters sheds some doubt on the hypothesis of Pd-olefin-carbene complexes (see Sect. 11). 

Diaminobenzene-IV,IV,IV, IV -tetraacetate (248, 250) and chloro- and methyl-ring-substituted derivatives (248)... 

M. Fahlman, M. Logdlund, S. Stafstrom, W.R. Salaneck, R.H. Friend, P.L. Burn, A.B. Holmes, K. Kaeriyama, Y. Sonnoda, O. Lhost, F. Meyers, and J.L. Bredas, Experimental and theoretical studies of the electronic structure of poly(p-phenylene vinylene) and some ring-substituted derivatives, Macromolecules, 28 1959-1965, 1995. 

The first CPO-catalyzed epoxidation was reported by McCarthy and White in 1983 [137]. Since this discovery, several research groups have intensively studied the substrate selectivity of this enzyme for the enantioselective epoxidation. As shown in Table 8, styrene and its ring-substituted derivatives are epoxidized by CPO in moderate enantiomeric excesses (entries 1 -8). In contrast, for the cis- -methylstyrene (entry 9) and tetrahydronaphthalene (entry 11) high enantio-selectivities were observed, while the trans-j3-methylstyrene was not converted by CPO (entry 10). 

The specific rates of solvolysis of benzyl p-toluenesulfonate and nine benzylic-ring-substituted derivatives (324) have been satisfactorily correlated using Aij and Tots scales within the extended Grunwald-Winstein equation. The reactions of Z-phenylethyl X-benzenesulfonates (325) with Y-pyridines (326) in acetonitrile at 60 °C have been studied at high pressures. The results indicated that the mechanism of the reaction moves from a dissociative 5)vr2 to an early-type concerted 5)vr2 with increasing pressure. 

Zinc Reduction. (This is a mild procedure used with great success on highly ring substituted derivatives.) CPB, 16(2), 217. 

When (40) is irradiated by Hg lamp at room temperature in the presence of pentamethyl-cyclopentadienyl dicarbonyl cobalt(III), Co(III) dithiolato complexes (45) and (46) are formed implying involvement of benzonitrile sulfide as an intermediate <92CL243). Thermolysis of (40) (and its phenyl ring substituted derivatives (40a)) at 110-140 °C in aromatic solvents results in formation of another heterocyclic mesoionic structure (47) and appears to proceed as a radical process (Scheme 2) (91TL4023). The reaction is inhibited by radical scavengers. 

N,N -Diphenylurea is a compound isolated and identified as a cell-division factor of coconut milk which exerts the same activity as the N6-substituted adenines in the cytokinin tests 45). Bruce and Zwar synthesized a number of ring substituted derivatives and determined their activity46. We tried to analyze quantitatively their data for derivatives where one of the benzene rings is unsubstituted (22)44). 

Structures are arranged in this section according to the kind of atom attached to the cyclopropane ring. Substituted derivatives with an sp3, sp2 and sp carbon atom are followed by those with halogens, oxygen, nitrogen etc. Mixed derivatives are discussed under the substituent group of our primary interest. 

Aminobenzo[6]thiophene and its simple ring-substituted derivatives are most conveniently obtained by reduction of the corresponding nitro compound with tin and hydrochloric acid,883,334,544,545 iron and hydrochloric acid,555 ferrous sulfate and ammonia,185,330 333 334,497 sodium borohydride and palladized charcoal,337 cata-lytically,152, 422,488,543 or, preferably, with Raney nickel and hydrazine hydrate.152,298,338,497,556 Several 5-aminobenzo-[6]thiophenes may also be made by cyclization reactions (Section IV, D).239,330,331 333,494... 

The formation of 59 and related adducts in the reactions of t-1 and several of its ring-substituted derivatives with 1,4-cy-clohexadienes (110) provides the only example of acyclic adduct formation between a stilbene and electron-rich or electron-poor alkenes (see, however, Section VI). Kaupp has proposed that... 

Cyclizations shown in Eq. (4.45) have been used to obtain. S -peril uoroalkyl-benzothiophenium ion 64 and ring-substituted derivatives.174,175 Salts 64 and the. S -(difI uoromethyl)- and. S -(monofluoromethyl)-diarylthiophenium salts 65 reported recently by Prakash, Olah, and co-workers176,177 are used as fluoromethylating agents. 

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