Benzophenones synthesis

Poly(2,5-benzophenone), synthesis of, 492 Polybenzothiazole, synthesis of, 314-319 Polybenzoxazoles, synthesis of, 292, 314-319... 

Pyran-2-one, 4-hydroxy-6-phenacyl-benzophenones from, 3, 686 Pyran-2-one, 4-hydroxy-6-phenyl-synthesis, 3, 795 Pyran-2-one, 4-methoxy-6-substituted... 

The methoxy group of methoxythiophenes shows a reactivity which, in many respects, differs appreciably from the reactivity of the corresponding anisoles. Thus, in an attempted Hoesch synthesis with 5-methoxy-2-thenylcyanide (167) and phloroglucinol, the methoxy group reacted instead and 5-(2, 4, 6 -trihydroxyphenyl)-2-thenyl cyanide (168) was obtained. 2-Thenyl cyanide reacts normally in the Hoesch synthesis, Likewise, upon acid hydrolysis of the reaction product of 5-methoxy-2-thienyllithium with benzophenone, (169) was obtained instead of the expected substituted methoxythiophene. No defined products could be isolated from the attempted Claisen rear-... 

An ingenious synthesis of 1-arylisoindolcs has been developed by Vebor and Lwowski, based upon the reaction of an o-phthalimido-methylbenzophenone (41, R = aryl) with hydrazine (Table IV). The benzophenone is prepared by a Friedel-Crafts reaction with o-phthalimidomethylbenzoyl chloride (40). The mechanism of isoindole formation can be represented sehematically by a sequence involving attack by hydrazine at the imide to give the ring-opened hj drazide (42), followed by cyclization to phthalazine-l,4-dione (44) with displacement of the o-aminomethylbenzophenone (43). Intramolecular condensation of the latter can lead, via the isoindolenine... 

The intermolecular McMurry reaction is first of all a suitable method for the synthesis of symmetrical alkenes. With a mixture of carbonyl compounds as starting material, the yield is often poor. An exception to this being the coupling of diaryl ketones with other carbonyl compounds, where the mixed coupling product can be obtained in good yield. For example benzophenone and acetone (stoichiometric ratio 1 4) are coupled in 94% yield. ... 

Intramolecular arylations can also be carried out photochemically. Huisgen and Zahler (1963 a) prepared fluoren-9-one by irradiation of benzophenone-diazonium salts in dilute sulfuric acid. The classical Pschorr synthesis of phenanthrene-9-carb-... 

The Ullman reaction has long been known as a method for the synthesis of aromatic ethers by the reaction of a phenol with an aromatic halide in the presence of a copper compound as a catalyst. It is a variation on the nucleophilic substitution reaction since a phenolic salt reacts with the halide. Nonactivated aromatic halides can be used in the synthesis of poly(arylene edier)s, dius providing a way of obtaining structures not available by the conventional nucleophilic route. The ease of halogen displacement was found to be the reverse of that observed for activated nucleophilic substitution reaction, that is, I > Br > Cl F. The polymerizations are conducted in benzophenone with a cuprous chloride-pyridine complex as a catalyst. Bromine compounds are the favored reactants.53,124 127 Poly(arylene ether)s have been prepared by Ullman coupling of bisphenols and... 

Tetramethydisiloxane was purchased from Lancaster Synthesis Inc. and used as received. THF was obtained from Mallinckrodt Inc. and freshly distilled from sodium/benzophenone ketyl. 

More recently, catalytic asymmetric allylations of imines and imine derivatives in aqueous media have been studied. An /V-spiro C2-symmetrical chiral quaternary ammonium salt (5,5)-I-Br (,S, .S )-()-Np-NAS-Br] has been evaluated in the allylation of glycine tert-Bu ester benzophenone Schiff base [Ph2C=NCH2COOCMe3] for synthesis of both natural and unnatural a-amino acids (Eq. 11,45).76... 

Scheme 39. Synthesis of norchelerythrine (222) by photocyclization. Reagents a, KOBu, benzophenone, dioxane b, CH2N2, CH2C12 c, hv, benzene.

Though the triplet sensitized photolysis of isoprene (159) does, as noted above, produce a complex mixture of products, one of these adducts has been used in the context of complex molecule synthesis (equation 5)71. Cyclobutane 160, which was formed in ca 20% yield by the benzophenone sensitized photolysis of 159, could be easily transformed into fragrantolol, 161, an isomer of grandisol isolated from the roots of the Artemisia fragrans, by simple hydroboration/oxidation of the less hindered double bond. 

The products of such reactions can be useful intermediates in the synthesis of commercial drugs. The nature of the substituents within the benzophenones has an effect on rate, with electron-withdrawing groups favoring the reaction more than electron-donating groups. For example, kinetic studies showed that p-trifluoromethylbenzophenone was hydrogenated 11-fold faster than the p-... 

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