L- benzo

The same substrate (451) and 4-phenylhydrazono-3,4-dihydro-2//-l-benzo-pyran-2,3-dione (454) [prepared from the dione (452) with benzenediazo-nium chloride] gave 3-(o-hydroxy-a-phenyUiydrazonobenzyl)-2(l//)-quinox-alinone (455) (EtOH-AcOH, reflux, 90 min 80%). ... 

Finally, many [4+2] cycloaddition strategies utilizing various substituted thiophenes as dienes have been reported. The reaction between 2-(prop-l-enyl)-l-benzo[fo]thiophene and 3-chlorocyclobut-3-ene-l,2-dione followed by bromination and loss of HBr gives a... 

Method B involves the preparation of precursor of 2-alkyl-l-benzo-pyrylium salts, as shown in Scheme ll.50 2-Alkylbenzopyrylium salts have been prepared by condensation of salicylaldehyde with appropriate ketone in acetic acid or by alkylation or reduction of coumarin or chromone derivatives. Reaction of 2-alkylbenzopyrylium salts with salicylaldehyde gives directly a spirodibenzopyran or 2-vinynologue benzopyrylium salt 17 which then can be converted into the spirodibenzopyran by piperidine or pyridine. 

Another method for the synthesis of hydantoins is the cyclization of A-(l-benzo-triazolylcarbonyl)phenylalanine butylamide.[147 ... 

In the reactions which we have just discussed, the initial reaction involves only the carbonyl group. We therefore looked next at reactions of tetrachlorobenzyne with simpler aldehydes. It is noteworthy that o-carboxybenzenediazonium salts are known to yield 1,3-benzodioxan-4-ones, for example, (129) with carbonyl compounds 166>, and 2,2-diphenyl-3,l-benzo-oxathian-4-one (130) with thiobenzophenone 167>. These products are presumably formed via reactions with the intermediate (128). 

Wen-Chen Z, Ling-Jun L, Xian-En Z et al (2008) Application of 2-(l l//-benzo[ i]carbazol-11 -yl) ethyl carbonochloridate as a precolumn derivatization reagent of amino acid by high performance liquid chromatography with fluorescence detection. Chin J Anal Chem 36 1071-1076... 

As with five-membered heterocycles, phosphorus pentasulfide may replace a ring oxygen atom by sulfur, or it may effect replacement in an acyclic precursor and then bring about cyclization. Thus isochroman-l-one (99) is converted into thioisochroman-l-thione (100) under the same conditions a 3-arylisocoumarin( 101) produces a 3-ary 1-1-thioisocoumarin (102) only, with no replacement of the ring oxygen atom.122 A typical example of thiation, followed by cyclization, is the formation of 2-alkyl- or 2-aryl-3,l-benzo-thiazine-4-thiones (103) from /V-acylanthranilic acid esters (104) by treatment with phosphorus pentasulfide in boiling xylene.122... 

Formation of the BPDE-DNA adduct requires a study of (l) Benzo ring conformations of BPDEs and adducts (2) The rehybridization of amino groups on the benzo for the C10-N bond formation (3) The receptor sites resulting from a conformational adjustment of DNA to accommodate an intercalated and finally an intercalative covalently bound BPDE, and the base sequence specificity in the formation of the receptor site (U) Classical intercalation and the orientation of CIO of the BPDEs toward the reactive N2(G), N6(a), 06(G) and... 

Amino-3-methylisoxazole, 1502 2-Amino-4-methyloxazole, 1500 5-Amino-3-methylthio-l,2,4-oxadiazole, 1192 Ammonium A-nitrosophenylaminooxide, 2399 2-Aza-l,3-dioxolanium perchlorate, 0898 Azoformaldoxime, 0815 Bis(l-benzo[d]triazolyl) carbonate, 3598 Bis(l-benzo[d]triazolyl) oxalate, 3629 Bis(trifluoromethyl) nitroxide, 0638 2-/er/-Buty 1-3 -phenyloxaziridine, 3406 Calcium bis(O-hydroxylamide). 3930 Calcium hydroxide O-hydroxylamide, 3929... 

New rearrangements of 2-imino-2//-l-benzopyran-3-carboxamides under the action of anthranilic acid as an N-nucleophile have been revealed. Depending on the conditions 2-(2-oxo-2//-l-benzopyran-2-yl)-3//-quinazolin-4-ones or 2-oxo-2//-l-benzo-pyran-3-((V-2-carboxyphenyl)carboxamides were found to be the products. 

Benzopyrrole, see Indole Benzo[6]p3UTole, see Indole l-Benzo[6]pyrrole, see Indole... 

A series of C-nucleoside analogs of type 1.5 were prepared from the reaction of 1-bromodeoxyheptulose derivatives with 3-arylamino-2-cyano-3-mercaptoacrylic acid ethyl ester, 3-amino-5-thioxopyrazolin-4-carboxylic acid ethyl ester, and 2-amino-4-thioxo-4,5-dihydro-l//-benzo[b][l,4]-diazepin-3-carboxylic acid ethyl ester (86PHA548). 

Bis(5-amino-l,3,4-triazol-2-yl)triazene, 1576 Bis(l-benzo[i/]triazolyl) carbonate, 3598 Bis(l-benzo[i/]triazolyl) oxalate, 3629... 

Very recently, a series of novel carbocations and carboxonium ions were generated from 77/-benzo[c]fluorene (80), 1 l//-benzo[Z)]fiuorene (81), ll//-benzo[a]fluorene (82), 2-methoxy- (83), 7-methoxy- (84), and 9-methoxy-l l//-benzo[u]fluorene (85), 7//-dibenzo-[c,g]fluorene (86), 137/-dibenzo[u,g]fluorene (87), 2-methoxy-13//-dibenzo [u,g]fluorene (88), and 5,6-dihydro-13//-dibenzo[u,g]fluorene (89) (Fig. 30). Charge delocalization modes in the resulting carbocations were derived based on experimental and/or computed (GIAO-DFT) A8 C NMR values and via the NPA-deiived changes in charges (A ). 

Pyrimidine 1 is the lUPAC accepted name for 1,3-diazabenzene, while quinazoline 2 is the accepted name for benzo[r lpyrimidine or 1,3-diazanaphthalene. Perimidine 3 is the lUPAC accepted name for l//-benzo[r/ ]quinazoline or H -naphtho[l,8-r/i ]pyrimidine, while benzo. 4]perimidine 4 is also known as 1,3-diazapyrene. 

Alkylidene-phosphapyrazolines 98-101 are much more thermally stable than their relatives 88, which do not possess the exo-methylene substitution. Dediazo-niation of 98 required heating in toluene at 110°C and gave one or more of the following products, probably via intermediate diphenylmethylene(vinylidene)phos-phoranes methylenephosphiranes, (2-siloxyvinyl)phosphanes, 2//-l,3-oxaphos-pholes, and l-alkylidene-2,3-dihydro-l//-benzo[c]phospholes (169). Thermolysis of 100 ( R = t-Bu, 1-adamantyl) afforded isolable 2-phosphabutadienes (169). The photochemical elimination of N2 from 98 generated cyclic azomethine imine dipoles 104 (Scheme 8.24), which rearrange to compounds 105 and 106 that could be further trapped with DMAD to form 107 (170). 

Garanti et al. (30a) reported a synthesis of the l,2,3-triazolo[l,5-a][4.1]benzox-azepine 149 via an intramolecular cycloaddition of an aryl azide with an acetylene (Scheme 9.30). By using a similar strategy, the l,2,3-triazolo[l,5-a][l,4-l ]benzo-diazepine 150, an analogue of Flumazenil, was also reported (30b,c). As an extension of this method, the l,2,3-triazolo[l,5-a][l,4]benzodiazepine-6-one 153 was synthesized using an intramolecular 1,3-dipolar cycloaddition of an azide with a cyano group (30d). 

Hydroxyphenyl)-5-methoxy-6-(3,3-dimethylallyl)-2",2"-dimethylchromene-(5",6" 8,7)-3-(propyl-2-one)-47T-l-benzo-2,3-dihydropyran-2,4-dione. 

H 1. R—MgBr/CuJ/THF/Elher Zugabe des Eduktes bei --10° dann 20 25s A- 6h 2. HCl/HjO R 5-Amino-4-butyl-l-benzo- thiophen 5-Amino-4-benzyl-l-benzo- thiophen 60 63 2... 

Oxo-2,3-dihydro-l-benzo-furan-ifl-spiro-S -1,4-dimethyl-1,4-diazepanl... 

Dihydro-4,8-dihydroxy-l(2H)-naphthalenone 8-[5-(2,3-Dihydro-5,7-dihydroxy-4-oxo-4//-l-benzo- Isosclerone... 

Dihydro-5,7-dihydroxy-4-oxo-4H-l-benzo- pyran-2-yl)-2,3-dihydroxyphenyl]-5,7-dihydroxy- 2-(4-hydroxyphenyl)-4//-l-benzopyran-4-one 2,3-Dihydro-5 -hydroxyamentoflavone... 

---