Coumarin chloro

Scheme 2.155. Reaction of the chloro-coumarin dimer 2-693 with primary amines.

Coumarilic add has also been prepared by Perkin from 3-chloro-coumarin and from 3-bromocoumarin by the action of alcoholic potassium hydroxide.2... 

The compound 7-(4-chloro-benzyl)-2-(4-chloro-phenyl)-3,8a-dihydro-pyridazino[4,3-( ][l,3,4] thiadiazin-8-one 42 has been reported to be active against Bacillus Escherchia coli, Staphylococcus aureus, and Pseudomonas aeruginosa by a serial dilution method <2001IJB475>. Triazino-thiadiazines 24f, 25b, 25c, and 25f <2002IJH287> have been reported to be active against S. aureus-, sydnone derivatives of triazino-thiadiazine 24f <2002IJH287> are more reactive than coumarin derivatives. 

The first, and still the most commonly used, of the tunable lasers were those based upon solutions of organic dyes. The first dye laser was developed by Sorokin and Lankard 05), and used a "chloro-aluminum phthalocyanine" (sic) solution. Tunable dye lasers operating throughout the visible spectrum were soon produced, using dyes such as coumarins, fluorescein, rhodamines, etc. Each dye will emit laser radiation which is continuously tunable over approximately the fluorescence wavelength range of the dye. 

An example of anomalous behavior in closely related systems was reported some time ago during an investigation of the cychzation products derived from coumarin semicarbazones (Scheme 6.21). Thus, 78a reacted cleanly with chloro-acetic acid to yield 79a, which cyclized to the expected product 80a upon treatment with sodium acetate. On the other hand, 79b did not cyclize under the same reaction conditions. This was attributed to the absence of the enolizable hydrogen (Ph vs. H). The authors did not comment on the possibility of cyclization of 79b to 80b. The closely related urea analogue 81 did not react with chloroacetic acid thereby... 

The important points that emerge from the studies on the five chlorocoumarins in the solid state are the following, (a) All chloro substituted coumarins (7-chloro, 6-chloro, 4-chloro, 4-methyl 7-chloro and 4-methyl 6-chloro coumarins) undergo dimerization in the solid state. While four of these give syn head-head dimer as the photoproduct, 4-chlorocoumarin gives a mixture of anti-head-tail and syn head-tail in poor yields ( 25%). (b) Two of them namely 4-... 

Cathodic reduction of the trichloroacetates 673 affords 3-chloro-coumarins in moderate yield (Equation 272). When salicylaldehyde derivatives 674 are reduced a mixture of 3-chloro-coumarins and ( )-l-chloro-2-(2-chloroprop-l-enyl)benzenes 675 are formed (Equation 273) <2003T9161, 1999JEC201>. 

Compounds according to entries 1, nitrato-triphenyl-(pyridine-N-oxide)tin 2, (l,2-benzisothiazol-3(2//)-one-l,l-dioxide)-(quinoline-N-oxide)triphenyltin 3, chloro-(2,6-dimethylpyridine-N-oxide)trimethyltin 4, dichloro-(2,6-dimethylpyridine-N-oxide)diphenyltin 5, (coumarin-3-carboxylato)(quinoline-N-oxide)triphenyltin 6, isocyanato-(pyridine-N-oxide-O)-triphenyltin 7, bis(A,A)-dimethyldithiocarbamoylKacetato-0)(quinoline-N-oxide)tnphenyl-tin 8, (isopropylxanthato)(quinoline-N-oxide)triphenyltin. 

Coumarin (3 carbethoxy 4 hydroxy) coumachlor Coumarin (3 chloro 4 methyl 7 hydroxy) coumaphos... 

Coumarins undergo nitration readily in the 6-position, while bromination results in substitution at the 3-position as a consequence of an additionelimination sequence. Quinazolines nitrate in the benzene ring for example, 5-chloro-4 (3//)-quinazolinonc nitrates at C(8) <2005BMC5613> and 5-fluoro-4(3//)-quinazolinone gives a 4 1 mixture of the 6- and 8-nitro derivatives <1991JHC1459>. 

Formylation of 5,7-dihydroxy -( -propyl)-coumarin (1) provided on 8-formy-lated product (26). Treatment of the compound 26 with 3-chloro-3-methyl-l-butyne to introduce regioselectively the chromene 27 because the phenolic hydroxyl group at the C position was less accessible for formylated substitution because of a presumed hydrogen-bonding interaction. To construct the enantiomerically pure rra i-2,3-dimethyl chroman-4-ol system, Deshpande et al." ° used organoborone... 

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