Chloro dehydroxylation

Selective C4 monochlorination can be accomphshed when the reaction is performed with Ml-substituted 2-quinolones, however, when performing the transformation on N-unsubstituted 2-quinolones both the 2 and 

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Scheme 11 Chloro dehydroxylation of 4-hydroxy-2-qninolones under microwave irradiation...

Canthine skeleton 52 Cardiotonic agent, heart failiu-e 3 Caspase-3 inhibitors, non-peptide 269 Catch and release , 2,4,5-trisubstituted pyrimidines 98 Chloro dehydroxylation 17 Click chemistry, 1,4-disubstituted triazoles 45... 

Dibenzofuran, I- and 2-hydroxy-chlorination, 59, 251 chloro-dehydroxylation, 59, 251 Dibenzofuran, methoxy-, dimethoxy-, bromination, 59, 252 Dibenzo[/, /i]quinazoline-2,4-dione, 1,3-dimethyl-, 55, 226... 

Knoevenagel condensation of cyanoacetamide to ethyl [3- C]acetoacetate and cyclization afforded 3-cyano-4-methyl-2,6-dihydroxy[4- C]pyridine (330)- Chloro-dehydroxylation upon treatment with POCI3, Pd-catalyzed hydro-dehalogenation and saponification of the cyano function converted 330 into 4-methyl[3- C]nicotinic acid (321). ... 

At temperatures above 140 °C, [ C]urea decomposes to give NH3 and [ " C]isocyanic acid, which can trimerize to give [ " C3]cyanuric acid (37). A practical preparation of 37 consists in heating a mixture of [ CJurea in the presence of NH4C1 the yield is about 60%. In analogy to the preparation of 22 and 21, chloro-dehydroxylation of 22 provides [U- Clcyanuric chloride (38) " (Figure 9.10). 

The same intermediate 349 was also converted into ( )-montanine (338), ( )-pancracine (339), and ( )-brunsvigine (356). Dehydroxylation of 349 by way of a mesate gave 3-benzyloxy-A -5,ll-methanomorphanthridine (352), along with the regioisomer, in 70% yield. Chlorophenylselenyla-tion-dephenylselenylation of 352 gave 3-benzyloxy-2-chloro-A < -5,ll-... 

The dehydroxylation of the y-keto-a-hydroxy carboxylic acid on Scheme 3.63 may be related to the above dehalogenation in that it is supposed to take place via formation of an intermediate chloro-compound in the acidic reaction mixture [370],... 

A transfer hydrogenation modification has been described of a known dehydroxylation procedure (ref.52) in which the phenyl ether with 1-chloro-2-phenyltetrazole is used. The tetrazolyl ether stirred in benzene/ethanol/water (7 3 2) with 10% Pd-C was treated dropwise with 64% aqueous hydrazine, with TLC monitoring for completion of reaction, to give naphthalene in 82% yield (ref.53). 

A superior method was used for the dehydroxylation of estrone in 96% yield by initial reaction with 3-chloro-1,2-benzoisothiazole-1,1-dioxide (RCI) in refluxing toluene containing triethylamine (yield 100%) followed by heating in benzene with aqueous sodium hypophosphite for 15 minutes in the presence of 10% Pd-C (ref.54). 

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