2,3-Diphenyl-6,7,8,9-tetrahydro

Diphenyl-3-[3-(2-phenylimidazol-l-yl)propyl]-l,2,4-triazine (70) underwent thermal intramolecular addition (with loss of nitrogen) to give the tricyclic intermediate (71) and thence (by loss of benzonitrile) 2,3-diphenyl-5,6,7,8-tetrahydro-l,5-naphthyridine (72) [substrate, antioxidant (2,6-di-terf-butyl-4-methylphenol), l,3,5-Pr 3C6H3, reflux, 3 h 92%] that could be aromatized to 2,3-diphenyl-1,5-naphthyridine (73) (l,3,5-Pr 3C6H3, reflux, air, 24h 91%) the latter product (73) was also made directly from the triazine (70) (neat substrate, Se, 330°C, 10 h 85%) analogs likewise.137,522... 

A number of reduction products of 2,8-dichloro-6,12-diphenyldibenzo[f>,/][l,5]diazocine (283) have been obtained (66JOC3356). LAH in ether gives mainly the frans-diphenyl-tetrahydro compound (282), whereas reduction in pyridine stops at the dihydro stage (284) (78%). Catalytic hydrogenation or zinc-acid reduction gives the tetracyclic indolo[3,2-6]indole system (286) which is readily oxidized back to the diazocine. Transannular cycliz-ation to (286) occurs on treatment of the dihydrodiazocine with NaH. Troeger s base derivatives, e.g. (287), were formed from the tetrahydro derivatives with formaldehyde. 

Dimethyl-4,5-diphcnyl-2,5-dihydro- 1108 t/.l-(b7w. meso)-l,3-Dimethyl-4,5-diphenyl-tetrahydro-... 

Electrophilic attack at carbon is a rare event, and generally involves an oxidative process. For example, 5,6-diphenyl-tetrahydro-2//-l,3,4-oxadiazin-2-one (74) (Section 6.17.7.2.1.1) is inert towards oxidation by HgO, whereas with lead tetraacetate fraws-stilbene is produced in 89% yield <65JA5716>. In contrast, under the same conditions, the dehydro-derivative (75) is oxidized more slowly and in much lower yield (14%) to diphenylethyne. 

Diphenyl-pyron-(4)-telrabromid, x-Tetrahrom.2.6-diphenyl.tetrahydro p n 17, 370, II409. 

Diphenyl-tetrahydro rron>dicarbon< saure-(3.5)-dimetnyle8ter 18, 500. II371. 

Lumazine, 5-methyl-6,7-diphenyl-5,6,7,8-tetrahydro-rearrangement, 3, 308 Lumazine, 8-methyl-7-oxo-7,8-dihydro-methylation, 3, 297 Lumazine, 7-methylsulfonyI-synthesis, 3, 299... 

Naphtho[l,2-h]pyrylium salts, 5,6-dihydro-2,4-diphenyl-synthesis, 3, 869 Naphtho[2,l-h]pyrylium salts synthesis, 3, 866 Naphthoquinolines, tetrahydro-synthesis, 2, 469 N aphtho[ 1,2-7]quinolines Skraup synthesis, 2, 467... 

H-1,2-Oxazine, 3,6-dihydro-6-(2-pyridyl)-mass spectra, 2, 529 2H-1,2-Oxazine, tetrahydro-synthesis, 2, 92 4H-l,2-Oxazine, 5,6-dihydro-pyrolysis, 3, 999 synthesis, 3, 1017 tautomerism, 3, 999 4H-1,2-Oxazine, 5,6-dihydro-3-methyl-metallation, 1, 484 4H-l,2-Oxazine, 5,6-dihydro-3-nitro-reactions, 3, 1000 6H-l,2-Oxazine, 3,5-diphenyl-stability, 3, 997 synthesis, 3, 1014... 

Pterin, 6,7-dimethyl-5,6,7,8-tetrahydro-configuration, 3, 281 conformation, 3, 281 Pterin, 6,7-diphenyl-chlorination, 3, 296 methylation, 3, 297 reduction, 3, 307 Pterin, 6,7-diphenyl-5,6-dihydro-properties, 3, 306 UV spectrum, 3, 279 Pterin, 6-ethyl-5,6,7,8-tetrahydro-configuration, 3, 281 Pterin, 6-formyl-synthesis, 3, 318 Pterin, 6-formyl-5,8-dihydro-synthesis, 3, 306... 

H-Pyrazino[l,2-a][l,3,5]triazine, 2-amino-8-methyl-4,9-dioxo-cis-6,7-diphenyl-6,7,8,9-tetrahydro-... 

The results are consistent with the rate-determining step being addition of the aryl radical to the aromatic ring, Eq. (9). Support for this mechanism is derived from the results of three other studies (a) When A -nitrosoacetanilide is decomposed in pyridine, the benzene formed by abstraction of hydrogen from pyridine by phenyl radical accounts for only 1 part in 120 of the reaction leading to phenyl-pyridines. (b) 9,9, 10,lCK-Tetrahydro-10,10 -diphenyl-9,9 -bianthryl is formed in the reaction between phenyl radicals and anthracene, probably by the addition mechanism in Eq. (11). Adducts are also formed in the reactions of benzyl radicals with anthracene- and acridine. ... 

Drefahl and Horhold discussed the mechanism of N 0 acyl migration in A -benzoyl-l,2-diphenyl-3-aminopropanols. The migration does not seem to be possible in the erythro isomer as it would give an intermediate tetrahydro-1,3-oxazine with a bulky phenyl group in axial position. Consequently the erythro isomer is cyclized with inversion to form 2,5,6-triphenyl-5,6-dihydro-l,3-4 -oxazine... 

Treatment of bis-lactim ether 420 with BuLi, then with cw-l,4-dichloro-2-butene in the presence of Nal afforded 3,4,9,9n-tetrahydro-6//-pyrido[l,2-fl]pyrazin-4-one (421) with 96% diastereomeric excess (97TA1855). Reaction of l,2-diphenyl-6-methyl-quinoxaline with 1,4-dichlorobutane in THF in the presence of Na at —78°C afforded a 3 1 mixture of 4a,5-diphenyl-9-methyl-l,2,3,4-tetrahydro-4a//-pyrido[l,2-n]quinoxaline and 4-(4-chlorobutyl)-2,3-diphenyl-6-methyl-1,4-dihydroquinoxaline (98JHC1349). 

Reports of 1,3-dipolar cycloadditions with l -azepines are uncommon. Methyl l//-azepine-l-carboxylate, however, with iV-phenylbenzylideneamine iV-oxide (42) undergoes cycloaddition at the C4 —C5 double bond to yield a 1 1 mixture (48 %) of the two stereoisomers of methyl 2,3-diphenyl-2,3,3a,8a-tetrahydro-6//-isoxazolo[4,5-r/]azepine-6-carboxylate (43).83 268... 

Natriumboranat/Kobalt(II)-chlorid (s.S. 115) reduziert aliphatische undaroma-tische Sulfoxide in Athanol mit guten Ausbeuten zu den entsprechenden Sulfanen. Mit dieser Methode erhalt man7 z.B. Dibutyl-sulfan (98% d.Th.), Diphenyl-sulfan (95% d. Th.) oder Thiuxanthen (100H/o d. Th.). Dibenzyl-sulfoxid und Tetrahydro-thiophen-1-oxid werden praktisch nicht angegriffen. 

Die Dihydro-Derivate sind bei diesen Potentialen offenbar bestandig das 2,3-Diphcnyl-5,6-dihydro-pyrazin jedoch wird bei —1,4 V (vs. SCE) unter Ar%y>nzum2,3-Diphenyl-1,4,5,6-tetrahydro-pyrazin weiterreduziert (an Quecksilber in geteilter Zelle 70% d. Th. F 106°). 2,3-Diphenyl-pyrazin (-1,75 V 15% d. Th.) und 2,5-Di-phenyl-l,2-dihydro-pyrazin (- 1,55 V 59% d. Th.) wird im selben basischen Milieu dagegen za 2,3-Diphenyl-bzw. 2,5-Diphenyl-piperazin reduziert1 ... 

Die Reduktion kann bis zum 3-Oxo(Thiono)-5,6-diphenyl-hexahydro-l,2,4-triazin weitergeftihrt werden, dabei wird jedoch beim 3-Oxo-tetrahydro-Derivat in Acetonitril bei pH — 1 (-1,0 V) unter Ringverengung das 2-Hydroxy-4,5-diphenyl-imidazol (50% d.Th. F 318°) gebildet. Zur Reduktion der N-Alkyl-l,2,4-triazinone s, S. 613. 

Oxo-2-methyl-5,6-diphenyl- 2,3-dihydro- 612 f. 3-Oxo-2-methyl-5,6-diphenyl-1,2,3,4-tetrahydro-613... 

Brom-2,3-dimethyl- 598 7-Brom-2.3-dimethyl-l,4-(bzw. 3,4 bzw. 5,8)-dihydro- 598 7-Brom-2,3-diphenyl- 88 7-Brom-2.3-diphenyl-5,6-dihydro- 88 7-Brom-l,2,3,4-tetrahydro- 88... 

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