Oxo compound derivatives

The hydroxy- and oxo-compounds derived from di- and tri-saccharides after the sequence of periodate oxidation, sodium borohydride reduction, and acid hydrolysis have been identified by g.l.c. of their 0-trimethylsilyl ether derivatives, thus giving useful information for linkage analysis. ... 

Sodium hydrogen sulfite Hydantoins from oxo compounds derivatives... 

Oxo compounds derived from 4,5-dihydropyrazole are often called pyrazolones. The most important class of pyrazolones refers to 2,4-dihydro-3H-pyrazol-3-one (2) as parent system, derived in its systematic nomenclature from 3H-pyrazol-3-one (3) and 3H-pyrazole (4) ... 

Amino-6-chloro-4-methyl- and 3-amino-6-chloro-5-methyl-pyridazine and 3-amino-6-methylpyridazin-4(l//)-one are transformed with sodium nitrite in the presence of acid into the corresponding oxo compounds. If concentrated hydrochloric acid is used, in some instances the corresponding chloro derivatives are obtained as side products. On the other hand, 3-, 4-, 5- and 6-aminopyridazine 1-oxides and derivatives are transformed into stable diazonium salts, which can easily be converted into the corresponding halo derivatives. In this way 3-, 4-, 5- and 6-bromopyridazine 1-oxides, 5-chloropyridazine 1-oxide, 3,4,5-trichloropyridazine 1-oxide and 6-chloropyridazine 1-oxide can be obtained. 

Amino groups a to nitrogen are hydrolyzed to the corresponding oxo compounds (as in the purines and pteridines) in bo h acid and alkaline conditions. Schiff bases are reduced to benzylamino derivatives with borohydride. 

The 6- and 7-quaternary salts of pyrido[2,3-d]pyridazine are reduced by borohydride with subsequent air oxidation to 5,6- and 7,8-dihydro oxo derivatives respectively (77BSF919), whilst the [3,4-d] analogues give the corresponding 1,2- and 3,4-dihydro oxo compounds 72CR(C)(275)1383). ... 

Alkylation of these mercapto compounds in alkaline solution gives only the S-methyl derivatives. Of the four isomeric A-methyl derivatives, the 4-thioquinazolines, (28) and (29), have been obtained from the corresponding oxo compounds with phosphorus pentasulfide but the corresponding 2-thio derivatives (30) and (31) are not known. However, derivatives of substance (31) with methyl replaced by... 

Dihydroquinazolines are normally stable compounds but they deteriorate on long standing. Some examples are known to oxidize to the corresponding 4(3H)quinazolinones. 3-Methyl-3,4-dihydroquin-azoline is converted to the 4-oxo compound after three recrystallizations from light petroleum. The most remarkable example is 3,4-dihydro-6-fluoro-3(p-fluorophenyl)quinazoline [(44), R = F] which oxidizes at its melting point (137°-I38°C), Other halogenated derivatives of (44) are more stable. ... 

The formation of quaternary salts by attack at an oxygen atom is only achievable in certain special cases. Most of the attempts to effect reactions of this type with N-alkyl-a-oxo derivatives have failed. Until recently it might have been assumed that 2-alkoxy-quaternary salts were unobtainable, the usual product from reactions with the alkoxy derivatives being the N-alkyl-oxo compounds (see Section IV,C). Recently, however, Meerwein and his co-workers found that triethyloxonium borofluoride and a number of N-methyl-a-oxo... 

The ionization potentials, using mass spectrometry, for both 2-hydroxy-and 3-hydroxythiophenes have been compared with data for compounds derived from either tautomeric form in order to analyze the tautomeric composition.124 125 In the 2-hydroxy-substituted system the enol isomer could not be detected. Of the two possible unsaturated lactones the oc,/l-unsaturated form was the major isomer. In the 3-hydroxy-substituted case both the oxo form and the enol form are important. The position of the equilibrium was compared with those of the corresponding furan and sele-nophene systems for both isomers. 

An efficient synthetic route to (10Z)- and (10 )-19-lluoro-la,25-dihydroxy vitamin D3 has been developed (488). The key feature of this pathway is the introduction of a 19-fluoromethylene group to a (5 )-19-nor-10-oxo-vitamin D derivative. The 10-oxo compound 445 has been obtained via a 1,3-dipolar cycloaddition reaction of (5 )-la,25-dihydroxyvitamin D with in situ generated nitrile oxide, followed by ring cleavage of the formed isoxazoline moiety with molybdenum hexacarbonyl. Conversion of the keto group of (5 )-19-nor-10-oxo-vitamin D to the E and Z fluoromethylene group has been achieved via a two-step sequence, involving a reaction of lithiofluoromethyl phenyl sulfone, followed by the reductive de-sulfonylation of the u-lluoro-j3-hydroxysulfone. The dye-sensitized photoisomerization of the (5 )-19-fluorovitamin D affords the desired (5Z)-19-fluorovitamin D derivatives, (10Z)- and (10 )-19-fluoro-la,25-dihydroxy-vitamin D3. 

Reduced derivatives of all these parent structures (dihydro, tetrahydro, and fully saturated systems) increase greatly the number of possible compounds. Oxo compounds are also possible, and each of the nine parent structures has five different positions where the carbonyl group could be located. 

Aromatic pyrrolo[l,2-r(]oxazoles cannot be drawn, and the only structure that one can find in the literature is the l //,3/7-derivativcs. The derivatives 377,5/7 and 3 //.7// are unknown. All compounds described are dihydro and mainly oxo perhydro derivatives. 

Pyrrolo[ 1,2-c]oxazolc itself was used for further elaboration of more complex molecules. The main members of this family that are used as intermediates in organic synthesis are the 3-oxo and 5-oxo perhydro derivatives. One can find also a number of 1,3-dioxo, 3,5-dioxo, 3,7-dioxo, and 5,7-dioxo perhydropyrrolo[l,2-r ]oxazoles that were prepared and/ or converted into another valuable compounds. 

Several radical approaches have been also used for the synthesis of 3-oxo-perhydro derivatives based on the use of trimethylstannyl chloride or tributylstannyl chloride activation in presence of 2,2 -azobisisobutyronitrile (AIBN) <1996JOC5418, 2000TL5915>. Photochemical strategies were applied to the formation of 3-oxo perhydro intermediates <1998J(P1)3577>. Compounds 348 and 349 were isolated as a 1 1 mixture after photolysis of 347 using a high-pressure mercury lamp in quartz tubes at room temperature in the presence of cr-trifluoro-acetophenone and KF (Equation 61) <2002TL7777>. 

A new development in silsesquioxane ehemistry is the eombination of sil-sesquioxanes with cyclopentadienyl-type ligands. Reeently, several synthetie routes leading to silsesquioxane-tethered fluorene ligands have been developed. The scenario is illustrated in Seheme 47. A straightforward aeeess to the new ligand 140 involves the 1 1 reaction of 2 with 9-triethoxysilylmethylfluorene. Alternatively, the chloromethyl-substituted c/oxo-silsesquioxane derivative 141 can be prepared first and treated subsequently with lithium fluorenide to afford 140. Compound 141 has been used as starting material for the preparation of the trimethylsilyl and tri-methylstannyl derivatives 142 and 143, respeetively, as well as the novel zirconoeene complex 144. When activated with MAO (methylalumoxane), 144 yields an active ethylene polymerization system. 

Other Reactions of Olefinic Steroids.—Reaction of cholest-5-en-3-one with air and acetic acid shows that isomerization to the A -3-oxo-compound is accompanied by autoxidation to the 6a- and 6/8-hydroxy-3-oxo-A -compounds and the 3,6-dioxo-A -compound. The oxidation appears to be controlled by heterolysis of the 4/3-proton and formation of the intermediate ion pair (73). Sitosterol was autoxi-dized at C-7 to give the 7-oxo- and the epimeric 7-hydroxy-derivatives. Oxidation of a 17-methylene steroid with Pb, Tl" , and Hg acetates in methanol gave a wide variety of products. The reaction with Pb(OAc)4 gave the rearranged products (74), (75), and (76) whereas the Tl and Hg products retained the... 

A synthesis of the B-ring aromatic corticosteroid (286), the analogue of cortex-olone, started with the previously reported B-ring aromatic norpregnane (285). Development of the corticosteroid side-chain employed bromination of the 17a-hydroxy-20-oxo-derivative with trimethylphenylammonium bromide perbromide. " Reaction of perchloryl fluoride with the mixed enol ethers (287) and (288) provided, after hydrolysis, the 17a-fluoro-20-oxo-compound (290) and the 21-fluoro-20-oxo-compound (291). In contrast, the enamine (289) led only to the 17a,21-difluoro-20-oxo-compound. A series of 17a-acyloxy-21-deoxy-... 

The application of the Friedlander reaction to 3-aminopyridine-2-carbaldehyde (135) gives good yields of the 2,3-disubstituted 1,5-naphthyridines (136) (75CR(C)(280)38l). The intramolecular cyclization of /3- (3-aminopyridinyl)acrylic acid (137) results in the formation of l,5-naphthyridin-2-one (138) (66JHC357), whilst the condensation of 3-aminopyridine-2-carboxylic acid or its esters (139) with active methylene compounds yields 4-oxo (132) and 4-hydroxy-2-oxo compounds (134 R = H) after hydrolysis and decarboxylation of the intermediates (140) and (134 R = C02Et). Reductive cyclization of the 3-nitropyridine derivative (141) gives the 1,5-naphthyridine (142) (71JOC450). 

Tee and Endo (76JHC149) reported a novel oxidative ring contraction of the 2-oxopyrimidinium bisulfates 176 to oxazolidindione 177 with excess hydrogen peroxide. The reaction took place only if one of the and R positions was not substituted, but failed with 4,6-dialkylated cations. A completely different reaction was observed when 176 (R = R = H) was oxidized in the presence of potassium iodide (78JHC493), leading to two uracils 178 (X = H and I) and small amounts of 177 (Scheme 30). Similar results were obtained with 179, which yields only 6-oxo derivatives 180 (X = H, I), but no isomeric oxo compounds 181 (Scheme 31). 

If appropriate, this commences with a brief historical piece, and comments on the relationship of the new chapter to the corresponding chapter in CHEC, and also gives general references to reviews of the material. The scope of the chapter is outlined with a survey of the various structural types and nomenclature of the parent, its non-conjugated isomers, partially reduced compounds, oxo compounds and benzo derivatives. Distinction is made here between the structural types possible and those which are known and treated in the chapter. 

In the fused benzofuran series, the same method, applied to bromoacyl-o-hydroxycoumarins502,549 and bromoacyl-o-hydroxyxan-thones321,433,550 allows the synthesis of the corresponding oxo-dihydrofuro derivatives. The nitrogenated analogs of compounds 237 (2,3-dihydro-3-oxofuro[2,3-6] and -furo[3,2-c] pyridines) have also been obtained.551,552... 

The unusual formation of N,N-dimethylaminophenyl substituted pyrimido[4,5-c]-pyridazines (74) by the reaction of the oxo compound (73) with phosphorus oxychloride and iV,AT-dimethylaniline has been reported (71CPB1849). The chlorination of other oxo substituted pyrimido[4,5-c]pyridazines with phosphorus oxychloride has been reported to be unsuccessful. Chloro derivatives of this heterocyclic ring undergo nucleophilic displacement with amines and hydrazine to give the corresponding amino and hydrazino substituted products. The catalytic dechlorination of these chloro substituted heterocycles has also been reported (68JHC523). 

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