7- Phenyl-l ,8-dihydro

The cycloadduct, l-phenyl-2,3-dihydro-l-benzothiophenium salt 59 is quite stable in the presence of hydroxide or methoxide anions at room temperature. When cycloadduct 59 reacted with sodium methoxide in methanol at 50 °C for 12 h, the ring opened product 243 was obtained in 96% yield (Scheme 41) <2003JOC731>. 

Dihydro-phosphol-l-oxide konnen andererseits als Dienophile in der [4+2]-Cyclo-addition fungieren. So erhalt man aus l-Phenyl-4,5-dihydro-phosphol-l-oxid und 1,4-Diacetoxy-l,3-butadien beim Erhitzen auf 150° l-Phenyl-2,3-dihydro-l-benzophos-phol-l-oxid (Schmp. 97-101°) in 50%iger Ausbeute434 ... 

The reaction course depends strongly on the structure of the starting phosphole. Thus, 4-niethyl-l-phenyl-2,3-dihydro-l//-phosphole 1-oxide did not react with dichlorocarbene, while 3,4-dimethyl-l-phenyl-2,5-dihydro-li/-phosphole 1-oxide yielded 4,5-dichloro-3,6-dimethyl-l-phenyl-l//-phosphepine 1-oxide 7 (2%) via four steps. 

Methyl-3-oxo-l-phenyl-2,3-dihydro-1 H-pyr-azoi(2-Methyi-l-phenyl-pyrazoiium-3-oiat) 33% Schmp. 123—124° (F.ssigsaure-ethylester/Hexan)... 

Durch Thermolyse oder Hydrolyse kann die Aminocarbonyl-Funktion in 2-Anilinocarbonyl-3-oxo-l-phenyl-2,3-dihydro-lH-indazol abgespalten werden, wobei intermediar eine Umlage-rung zu 3-Anilinocarbonyloxy-l-phenyl-lH-indazol beobachtbar ist353. 

The dehydrohalogenation reaction has been extended to benzannulated oxepins. Elimination of hydrogen bromide from 3-bromo-4-phenyl-2,3-dihydro-l-benzoxepin with 1,5-diazabicyclo-[4.3.0]non-5-ene gives 4-phenyl-1-benzoxepins 15a15 and 15b16 in low yield. 

Curiously, 6-(chloromethyl)-4-methyl-2-methylene-3-phenyl-3-azabicyclo[4.1.0]hept-4-ene-l,5-dicarbonitrile (31), obtained from 4,4-bis(chloromethyl)-2,6-dimethyl-l-phenyl-1,4-dihydro-pyridine-3,5-dicarbonitrile, rearranges via 4-(chloromethyl)-7-methyl-2-methylene-l-phenyl-2, 5-dihydro-l//-azepine-3,6-dicarbonitrile (32) to yield the 4-(chloromethylene)-4,5-dihydro-1//-azepine 33 as the final product.127... 

Analog erhalt man 3-Hydroxy-l-oxo-2-phenyl-2,3-dihydro-1 H-isoindol2 (40% d.Th. F 171-172°). 

This category is represented in the facile reaction of o-phenylenediamine (408) with 4-benzoyl-5-phenyl-2,3-dihydro-2,3-thiophenedione (409) (in toluene at 20°C for 30 min) to afford 3-(a-benzoyl-p-mercaptostyryl)-2(l//)-qumoxalinone (410) in 98% yield " also in the complicated reaction of 3-methyl-2,2,4-trinitro-2,5-dihydrothiophene 1,1-dioxide (411) with 2 equiv of ethyl 4-aminobenzoate (412) (in acetonitrile but no further details) to give ethyl 2-(p-ethoxycarbonylphenyl)-3-(l-methyl-2-nitrovinyl)-6-quinoxalinecarboxylate (413) in 51% yield.Several... 

Only one procedure has been reported recently within this category. Thus 7-chloro-l-methyl-5-phenyl-2,3-dihydro-lH-benzodiazepin-2-one 4-oxide (437) with dimethyl acetylenedicarboxylate in methylene chloride at 20° C for 3 days gave a separable mixmre of the primary tricyclic adduct, dimethyl lO-chloro-6-oxo-llb-phenyl-5,6,7, 1 lb-tetrahydroisoxazolo[2,3-t/] [ l,4]benzodiazepine-1,2-dicarboxylate (438), and its rearrangement product, 6-chloro-4-(2-methoxalyl-2-methoxycarbonyl-l-phenylvinyl)-l-methyl-3,4-dihydro-2(lT0-quinoxalinone (439) each product afforded 6-chloro-l-methyl-2(l//)-quinoxalinone (440) on refluxing in ethanol (see also Section 1.7.13). However, the final quinoxaline (440) was best obtained in 75% yield) by simply heating the initial substrate (437) and dimethyl... 

Amino-3-phenyl-3,4-dihydro-2(l//)-quinoxalinone (194) gave 5-phenyl-2,3-dihydro-17/, 5//-pyrazino[l,2,3-tie]quinoxaline-2,3,6(77/)-trione (195) [(COCl)2,... 

The crystal structures of 4-phenyl-2- 4-[4-(2-pyrimidinyl)piperazin-l-yl]butyl -2,3,5,6,7,8-hexahydro-177-pyrido[l,2-c][l,3]oxazine-l,3-dione <1995ZK899>, 4-cyano-l-phenyl-l-trifluoromethyl-2,3-dihydro-l/7-pyrido[l,2-r-]pyrimidin-... 

In the second, simpler scheme, synthesis begins with 7-chloro-5-phenyl-2,3-dihydro-l//-l,4-benzodiazepin-2-one (5.1.1), which is alkylated by cyclopropylmethylbromide in the presence of sodium amide into prazepam (5.1.11) [11,12]. 

The second way of making medazepam consists of the initial reduction of the carbonyl group by lithium aluminum hydride into 7-chloro-5-phenyl-2,3-dihydro-17f-l,4-benzodi-azepin-2-one (5.1.1)—the first intermediate product in the synthesis of diazepam—which is synthesized by the cyclocondensation of 2-amino-5-chlorobenzophenone with glycine ethyl ester into 7-chloro-2,3-dihydro-5-phenyl-17/-l,4-benzodiazepine (5.1.41), and the subsequent methylation of the secondary amine nitrogen atom of the resulting product by methyliodide, using sodium hydride as a base [41,42]. 

Chantrapromma, K. et al., 5-Hydroxy-7-methoxy-2-phenyl-4H-l-benzopyran-4-one (tectochrysin) and 2,5-dihydroxy-7-methoxy-2-phenyl-2,3-dihydro-4H-l-benzopyran-4-one isolation from Uvaria rufas and X-ray structures, Aust. J. Chem., 42, 2289, 1989. 

Dimethyl-3-(2-oxo-2-phenyl-ethyl--bromid lagert sich beim Kochen mit Triethylamin in Acetonitril in 2-(2-Imino-5-phenyl-2,3-dihydro-oxazol-3-yl)-4,6-dimethyl-pyrimidin um. Aus diesem werden durch Kochen in Alkoholen mit 4-Methyl-benzolsulfonsaure als Katalysator 2-Alkoxy-l-(4,6-dimethyl-2-pyrimidyl)-4-phenyl-imidazole oder durch Erhitzen mit primaren oder sekundaren Aminen ebenfalls in Gegenwart von 4-Methyl-benzolsulfonsaure 2-Alkylamino-l-(4,6-dimcthyl-2-pyrimidyl)-4-phe-nyl-imidazole erhalten374 ... 

Eine interne Abspaltung von Wasserstoff wird bei der Thermolyse von l,3-Dimethyl-2-(2-hydroxy-phenyl)-2,3-dihydro-benzimidazol beobachtet,. Auch die Oxidation mit Iod und dann Kalilauge liefert das innere Salz 1,3-Dimethyl-2-(2-oxy-phenyl)-benzimidazoIium (62 bzw. 90% Schmp. 245 -2470)354 ... 

Durch thermische Umlagerung von 3-(Ethylthio-carbonyl)-2-oxo-5-phenyl-2,3-dihydro-l,3,4-oxadiazol laBt sich 2-Ethylthio-5-phenyl-1,3,4-oxadiazol (45% Schmp. 39-40°) neben 5-Phenyl-2-thiono-2,3-dihydro- und 3-Ethyl-5-phenyl-2-thiono-2,3-dihydro-1,3,4-oxadiazol iso-lieren550. 

Die Einelektronen-Reduktion mit l,3-Dimethyl-2-phenyl-2,3-dihydro-benzimidazol lie-fert vergleichbare Ausbeuten wie mit 3-Aminocarbonyl-l-benzyl-l,4-dihydro-pyridin. Die Methode hat aber den Vorteil, daB das entstehende l,3-Dimethyl-2-phenyl-lH-benzimid-azolium-arensulfonat in einfacher Weise mit Boran in Methanol wieder zum 1,3-Dimethyl-2-phenyl-2,3-dihydro-lH-benzimidazol reduziert und dieses abgetrennt werden kann. Die Reduktion wird in Gegenwart von Azo-bis-isobutyronitril durchgefuhrt2 ... 

Bei der Hydrierung von aromatischen bzw. heteroaromatischen Nitro-alkenen mit in situ aus Benzaldehyd und 1,2-Diamino-benzol in Butanol hergestelltem 2-Phenyl-2,3-dihydro-benzimidazol werden keine Nebenprodukte gebildet und man erhalt selektiv l-Aryl-2-nitro- bzw. l-Hetaryl-2-nitro-alkane in Ausbeuten von 70-90% ... 

Two other azepine syntheses involving the interconversion of valence isomers are worthy of note, namely the isomerization of the novel 7-azatetracycloheptane (261), prepared from benzvalene as indicated in Scheme 34, to 1-phenyl-Iff-azepine (79TL1553) and the rearrangement of the syn isomer of the 2-azatricycloheptane (70 H in place of D), which at 120 °C yields l-ethoxycarbonyl-2,3-dihydro-Iff-azepine by a [w2s+ 4,] concerted process. As expected, the anti isomer, for which a concerted process would require a geometrically unfavoured [ 2a + w4a] process, rearranges only at 350 °C, and then by a non-concerted polar reaction (73JA7320). 

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