4,5-dibenzoyl-4,5-dihydro

A useful and possibly more general alternative to the Lwowski synthesis- of 1,3-diphenylisoindoles involves condensation of a l,2-dibenzoyl-l,4-cyclohexadiene (e.g., 55) with ammonia or a primary amine. Cyclohexadiene derivatives of this type are easily prepared by Riels-Alder addition of a 1,3-diene to dibenzoylacetylene, and these adducts lead directly, and in high yield, to the corresponding isoindoles (56). The reaction is closely related to the well-known synthesis of pyrroles by condensation of 1,4-diketones with ammonia. 4,7-Dihydro- and 4,5,6,7-tetrahydroisoindoles (57 and 58) have been... 

It is understandable that dihydro adducts should be formed by polycyclic compounds and not by benzene or pyridine, because the loss of aromatic resonance energy is smaller in the former than in the latter process, (c) When dibenzoyl peroxide is decomposed in very dilute solution (0.01 Af) in benzene, 1,4-dihydro biphenyl is produced as well as biphenyl, consistent with addition of the phenyl... 

The Reissert reaction of 3,4-dihydro-p-carboline (213) has also been studied 47,48). It has been shown that 3,4-dihydro-p-carboline (213) afforded 1-cyano-2,9-dibenzoyl-l,2,3,4-tetrahydro-P-carboline (214) with a phase-transfer catalyst and trimethylsilyl cyanide (Scheme 27). However, the normal Reissert product 2-benzoyl-l-cyano-l,2,3,4-tetrahydro-p-carboline (215) was obtained when a catalytic amount of anhydrous aluminum chloride was used in addition to the trimethylsilyl cyanide reagent. Reaction of 214 with sodium... 

Einen ungewohnlichen Verlauf nimmt die saure Hydrolyse von l-Benzoyl-2-(l,3-dibenzoyl-2,3-dihydro-imidazol-2-yl)-imidazol (Herstellung s.S.133), die zu 2-Aminomethyl-imidazol fiihrt (63%)1124 ... 

Bei den o.g. Oxidationen mit Singulett-Sauerstoff tritt oft auch Ringspaltung ein. So erhalt man z. B. aus 4,5-Diphenyl-imidazol je nach Reaktionsbcdingungen das cyclische Oxidations-produkt 4,5-Diphenyl 5-methoxy-2-oxo-2,5-dihydro-imidazol (I 36%)1233 oder den unter Ringoffnung gebildeten 1,3-Dibenzoyl-hamstoff (II 49%)1234 als Hauptprodukt. 

Cyan-l,3-dibenzoyl-2,3-dihydro-benzimidazol ist das Produkt einer Reissert-Reaktion mit Benzimidazol, Benzoylchlorid und Cyanid-Ionen385 Mit Natriumhydrid lagcrt es sich uber ein mesomeres Anion unter Eliminierung zu 2-Bemoyl-benzimidazol (81 % Schmp. 210 211 °)... 

Dibenzoyl-furazan-2-oxid liefert mit Alkenen bzw. Alkinen 3-(l-Benzoyloxyimino-2-oxo-2-phenyl-ethyl)-4,5-dihydro-l, 2-oxazole bzw. 3-(l-Benzoyloxyimino-2-oxo-2-phenyl-ethyl)-l,2-oxazole auf folgendem Weg450,451 ... 

Bei der Umsetzung des 3,4-Dibenzoyl-furazan-2-oxids mit Phenylhydrazin entsteht wahrscheinlich 4,5-Bis-[hydroximino]-1,3-diphenyl-4,5-dihydro-1 H-pyrazol 5i 59 ... 

Dibenzoyl-1,2,4,5-tetraketo-4,5-dihydro-pyridazine or 3,6-Dibenzoyl-4,5-pyrid[Pg.82]

Dihydro-5,10-disilanthracene and AIBN can reduce xanthates and thiocarbonates in refluxing cyclohexane solution. Reduction of xanthates with monosilanes such as PhSiH3 and Ph2SiH2 initiated by AIBN does not work effectively because of their strong Si-H bond dissociation energies. However, the same reactions using either dibenzoyl peroxide or triethylborane as an initiator do induce the effective reduction of xanthates. 

Saponara S, Kawase M, Shah A, Motohashi N, Molnar J, Ugocsai K, Sgaragli G, Fusi F (2004) 3,5-Dibenzoyl-4-(3-phenoxyphenyl)-l,4-dihydro-2,6-dimethylpyridine (DP7) as a new multidrug resistance reverting agent devoid of effects on vascular smooth muscle contractility. Br J Pharmacol 141 415-422... 

PhCO COPh PhCHOHCOPh 62 0, IC2CO3 (b.p.) 2,3-Dibenzoyl-4,5-dihydro-diphenyI-4-hydroxyfuran (39) 367... 

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