Phthalan

In the oxidation of PX and MX, formaldehyde is a degenerate branching intermediate, whereas phthalan is formed from OX ... 

Dihydroxy-21 -acetoxy-3,20-dioxo- 518 Piperidin-( 4-spiro-l) -phthalan... 

Another commercially available fluorescing reagent, "Fluorescamine", (4-phenylspiro(furan-2-(3H),T-phthalan)3,3 -dione) reacts directly with a primary amine in aqueous acetone at a pH 8-9. 

The naphthalene-catalyzed (2.5%) lithiation of phthalan 330 (or its substituted derivatives ) in THF at room temperature allowed the preparation of the functionalized benzyllithium intermediate 331, which reacted with electrophiles at —78°C to give, after hydrolysis, the corresponding functionalized benzyl alcohols 332 (Scheme 97). When carbon dioxide was used as the electrophilic reagent, the corresponding 5-lactone was directly obtained . When carbonyl compounds were used as electrophiles, the cyclization of the resulting products 332 under acidic conditions (85% H3PO4) allows the synthesis of substituted isochromans. 

Thiophthalan (364) gave a similar reactivity to phthalan (330). Thus, its lithiation using a catalytic amount of DTBB (5%) as the electron carrier in THF at —78 °C gave the intermediate 365, able to react with different electrophiles to yield, after hydrolysis, the corresponding functionalized thiols 366 (Scheme 106) . 

As was described for phthalan 330, the intermediate 374 has also been nsed for the EPC synthesis of branched-chain sugars 378 and 379"° and the steroid 380 in 15-70% yield, employing ketones 133 and 270, as well as 280, respectively. 

Lithium-titanium transmetallation of intermediate 374 made possible the chemoselec-tive discrimination between aldehydes and ketones, reacting mainly or exclusively with the first type of carbonyl compounds, as observed for the phthalan-derived intermediate 331. ... 

When carbon dioxide was used as the second electrophile, the acidic work-up (3 M HCl) afforded directly the corresponding lactones 457 in 55-58% yield. On the other hand, diols 456 were easily cyclized under acidic conditions (85% H3PO4, toluene reflux) to give quantitatively the corresponding substimted phthalans 458. 

DTBB-catalyzed (2.5%) lithiation of phthalan (330) (see also Section VI.C.l) was performed in a sequential fashion. After the first lithiation at room temperature the first electrophile was reacted at —78 °C, giving 487 as intermediates. After allowing the temperature to rise to 20 °C, a second lithiation took place giving the new intermediates 488, which finally were treated with a second electrophile giving, after hydrolysis, the difunctionalized products 489 (Scheme 137) . 

Synonyms Phthalic acid anhydride phthalan-dione 1,3-isobenzofurandione... 

AU of this led the groups of Maier et al. and Masamune et al. to reinvestigate the IR spectmm of CB, in search of possible bands that might have escaped detection in the experiments of Chapman and Krantz. To this end, they employed different precursors of which the formal adduct of CB with phthalan proved to be the optimally suited. 

Kinetic and mechanistic investigations on the o-xylene oxidation over V205—Ti02 catalysts were carried out by Vanhove and Blanchard [335, 336] using a flow reactor at 450°C. Possible intermediates like o-methyl-benzyl alcohol, o-xylene-a,a -diol, toluic acid and phthalaldehyde were studied by comparing their oxidation product distribution with that of toluene. Moreover, a competitive oxidation of o-methylbenzyl alcohol and l4C-labelled o-xylene was carried out. The compounds investigated are all very rapidly oxidized, compared with o-xylene, and essentially yield the same products. It is concluded, therefore, that these compounds, or their adsorbed forms may very well be intermediates in the oxidation of o-xylene to phthalic anhydride. The ratio in which the partial oxidation products are formed appears to depend on the nature of the oxidized compounds, i.e. o-methylbenzyl alcohol yields relatively more phthalide, whereas o-xylene-diol produces detectable amounts of phthalan. This... 

Activated alkynes have been shown to react in a Diels-Alder style with phthalans to furnish polysubstituted naphthalenes (80CJC2573). 1,1-Diethoxyphthalan (41) was prepared by alkylation of phthalide (40) with triethyloxonium fluoroborate, followed by treatment... 

Naphthol[l,2-c]furan and naphthol[2,3-c]furan have also been prepared from the corresponding phthalan precursors (83JCS(CC)1197 see also 83JOC3869 88AJC235). Anthra[2,3-c]furan was obtained similarly (in situ 96577). Gorgues and co-workers devised a simple route to isobenzofuran starting with the Diels-Alder adduct of the monoacetal of acetylendicar-baldehyde and cyclohexadiene. Reduction (with NaBH4) and acidic cy-... 

Phenylbenzo[c ]furan-3-carbonitrile and the corresponding carboxylic acid are catalyti-cally reduced in a cis manner to the expected 1,3-dihydro compounds. 1,3-Diaryl-benzo[c]furans are also reduced to phthalans with sodium amalgam. 

Fluorescamine, or 4-phenylspiro[furan-2(3//),l/-phthalan]-3,3,-dione, is used to introduce a fluorescent label on electroblotted proteins via reaction with free amines. Transferred proteins are visualized on blot transfer membranes with UV light. This stain can be very sensitive and can be used in conjunction with a second detection method such as immunoblotting (also see Basic Protocol 3). However, the protein is irreversibly modified because fluorescamine reacts with available amino groups (i.e., lysines and the protein N terminus if it was not previously blocked). 

Phenylspiro[furan-2(3 H), 1 -phthalan]-3,3-dione. see Fluorescamine Pheophorbides. see also Chlorophylls Pheophytins. see also Chlorophylls Phospholipids, 523... 

Fluorimetric methods for the determination of amino acids are generally more sensitive than colorimetric methods. Fluorescamine (4-phenyl-spiro[furan-2(3H),l -phthalan]-3,3 -dione) and o-phthaldialdehyde (OPA) substances are used for protein analysis. Fluorescamine reacts with amino groups to form fluorophores that excite at 390 nm and emit at 475 nm (Weigele et al., 1972). Applications of fluorescamine include monitoring the hydrolysis of K-casein (Beeby, 1980 Pearce, 1979) and quantification of proteins, peptides, amino acids in extracts (Creamer et al., 1985). OPA produces fluorescence on reaction with 2-mercaptoethanol and primary amines, with strong absorption at 340 nm. Lemieux et al. (1990) claimed that this method was more accurate, convenient, and simple for estimating free amino acids than the TNBS, ninhydrin, or fluorescamine methods. 

Chemical name for fluorescamine is 4-phenylspiro[furan-2(3H),l-phthalan] 3,3 -dione. 

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