Bromo structure

Earlier 4-bromo structural assignments should now be reversed. The 3-bromo derivative can be transformed into the desired chromene by zinc and acid.19 137... 

The chloro- and bromo-bridged complexes were first prepared by Werner (7). Werner originally formulated these complexes as singly bridged complexes (structure IX), but the /i-amido-/<-chloro and fi-amido-/i-bromo structures have recently been demonstrated by crystallographic studies (387, 388). The equilibrium constant Kl2 = Kt x K2 has been determined spectrophotometrically and the formation of structure X for X"- = Br is less favorable than its formation for the chloro analog (376, 379) (Table XXXVI). The equilibrium between... 

Trans-bromo structures are also found in the similar ditertiary phosphine bidentate complex [MnBr2(dmpe)2] (dmpe = l,2-bis(dimethylphosphino)ethane) 28 the Mn—P bond length in this compound (2.655 A) being comparable with that found in [MnCl2(diphos)2] (2.625 A). The reaction of [MnBr2(dmpe)] with LiAlH4 yields a Mn1 compound of stoichiometry Mn(AlH4)(dmpe)2 (Section 41.2.4). 

Two examples suffice to illustrate this reaction type, both involving 1-benzyltetrahydroisoquinolines. The 8-bromo structure (208) was photolyzed under alkaline conditions to ( )-mecambrine (209), in 10% yield, and the 7 -bromo relative (210) afforded dienone (211), 34% isolated, on the way to synthesis of ( )-boldine."°... 

Tertiary acetylenic halides give unsatisfactory results owing to further isomerization of the allenic halide into a conjugated diene system under the influence of the copper salt. Bromo- and iodoallenes with the structures R R2C=C=CH-X can also be synthesized by an aqueous procedure, consisting of reaction between... 

Treating 5.5 g of 2-amino-4,5-dimethylthiazole HCl with 0.66 g of solid sodium hydroxide 15 min at 220°C yields 53% of 4.4. 5.5 -tetramethyT 2,2 -dithiazolylamine, whose structure w as proved by identification with the produa obtained from the reaction between dithiobiuret and 3-bromo-2-butanone (467). This result is comparable to the reaction between 2-aminopyridine and its hydrochloride to yield bis(pyridyl-2)amine (468). Gronowitz applied this reaction to 2-aminothiazole, refluxing it with its hydrochloride 4 hr in benzene and obtained the dimeric 2-aminothiazole (236). He proposed a mechanism (Scheme 143) that involves the addition of a proton to the 5-position of the ring to give 234. The carbocation formed then reacts on the 5-position of a second... 

Two stereoisomers of 1 bromo 4 methylcyclohexane are formed when trans 4 methyl cyclohexanol reacts with hydrogen bromide Write structural formulas or make molecular mod els of... 

Owing to their particular interest two individual reactions will now be discussed separately. The reaction of methoxycarbonylhydrazine and 3-bromo-2,4-pentanedione affords, in addition to the expected pyrazole (608), a pyrazolium salt (609), the structure of which was established by X-ray crystallography (74TL1987). Aryldiazonium salts have been used instead of arylhydrazines in the synthesis of pyrazolines (610) and pyrazoles (611) (82JOC81). These compounds are formed by free radical decomposition of diazonium salts by titanium(n) chloride in the presence of a,/3-ethylenic ketones. 

H-Azepine, 2-allyloxytetrahydro-Claisen rearrangement, 7, 508 3H-Azepine, 2-amino-acylation, 7, 511 effect of acidification, 7, 510 nucleophilic displacement reactions, 7, 514 synthesis, 7, 533, 535 3H-Azepine, 2-amino-7-bromo-synthesis, 7, 529 3H-Azepine, 2-anilino-ring inversion, 7, 495-499 structure, 7, 533... 

Copper(II), di-/Lt-bromobis[bromo(pyridine)-structure, 2, 108 Copper 8-hydroxyquinolinate biocidal activity mechanism, 1, 401 fungicide, 1, 399 Copper nitrotetrazole as propellants, 5, 837 Copper phthalocyanine, 1, 333-334 colour and constitution, 1, 345 Coproporphyrin, 4, 382 Coproporphyrin, dehydro-, 4, 382... 

Coumarin, 7-amino-7-(diethylamino)-, I, 333 Coumarin, 7-amino-4-methyl-fluorescence spectra, 3, 601 Coumarin, 7-amino-3-phenyl-brightening agents, I, 339 Coumarin, 4-aryl-occurrence, 3, 677 synthesis, 3, 810 Coumarin, 3-arylazo-4-hydroxy-structure, 3, 643 Coumarin, 3-bromo-reactions... 

Indolizine, 3-benzoyl-6-bromo- l-(2-pyridyl)-structure, 4, 445 In4olizine, 3-chloro-synthesis, 4, 470 Indolizine, 3-cyano-cyclazine synthesis from, 4, 460 Indolizine, 8-cyano-synthesis, 4, 469... 

Oxetane, 3,3-bis(trimethylaminomethyl)-methane sulfonate X-ray crystal structure, 7, 365 Oxetane, 3-bromo-synthesis, 7, 390 Oxetane, 2-t-butyl-3-methyl-synthesis, 7, 399 Oxetane, 2-chloro-reactions, 7, 390 Oxetane, 3-chloro-synthesis, 7, 390... 

Selenophene, bis(TV-chlorothioimino)-molecular structure, 4, 939 Selenophene, 2-bromo-mercuration, 4, 946 Selenophene, 3-bromo-lithiation, 4, 949 synthesis, 4, 955 Selenophene, 3-bromo-2-lithio-synthesis, 4, 955 Selenophene, bromonitro-debromination, 4, 78 synthesis, 4, 955 Selenophene, 2-chloromethyl-solvolysis, 4, 952 Selenophene, 3-cyano-synthesis, 4, 955 Selenophene, deutero-deuterium exchange, 4, 949 Selenophene, 2,5-diacyl-3,4-dihydroxy-synthesis, 4, 964... 

In the early work, benzene formed the basis of a variety of multi-armed structures. Analogs bearing from 2—6 arms were prepared and compared for cation binding ability. The only indication of mode of synthesis for the hexa-substituted benzene derivative is that it was obtained on reaction of benzene-hexakis(methanethiol) and l-bromo-3,6,9-trioxatridecane . The reaction is illustrated in Eq. (7.6), below, devoid of reaction conditions and yields which were not specified. 

Kurath described the conversion of 3a,17y5-diacetoxy-5)9-androstan-12-one (partial structure 78) to diketone (79) by bromination of (78) and hydrolysis of the C-11 epimeric bromo ketones... 

FIGURE 13.19 The structure of 5-bromo-4-chloro-3-iudolyl-/3-D-galactopyra-uoside, or X-gal. 

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