4H-Pyrans

Pyridazines are formed from pyrones or their thioxo analogs or from appropriate pyridones. Pyrones or pyridones react with diazonium salts to give the corresponding hydrazones (187) and (188) which are rearranged under the influence of acid or base into pyridazinones as shown in Scheme 107. On the other hand, kojic acid is transformed with hydrazine into a 1,4-dihydropyridazine and a pyrazole derivative. 4H-Pyran-4-thiones... 

H- Pyran-4-one, 3,5-diacetyl-2,6-dimethyl-dipole moment, 3, 626 (37JCS1088) 4H-Pyran-4-one, 2-dichloromethyl- C NMR, 3, 588 (82S500)... 

H-pyran synthesis from, 3, 759 bis(trimethylsiloxy) in pyrrole synthesis, 4, 333 chromene synthesis from, 3, 750 cycloaddition reactions with isocyanates, azetidin-2-ones from, 7, 261 dihydropyran synthesis from, 3, 771 fuiyl... 

H-pyran synthesis from, 3, 762 Methylene, 2-pyridyl-ESR, 2, 144 Methylene, 3-pyridyl-ESR, 2, 144 Methylene, 4-pyridyl-ESR, 2, 144 Methyl eneimine... 

H-pyran synthesis from, 3, 757 tetrahydropyranone synthesis from, 3, 845 Pentane-1,5-diol, 1,5-diphenylring closure, 3, 774 Pentane-1,5-diols... 

H-pyran synthesis from, 3, 759 Propyne, 3-(2-amino-1 -benzimidazolyl)-isomerization, 5, 450 Propynoic acid, phenyl-ethyl ester... 

H-Pyran, 5-acetyl-2-amino-3,4,4-tricyano-6-methyl-synthesis, 3, 759... 

H-Pyran, 2-alkoxy-4-methyl-2,3-dihydro-conformation, 3, 630 4H-Pyran, 2-amino-IR spectra, 3, 593 synthesis, 3, 758 4H-Pyran, 4-benzylidene-synthesis, 3, 762 4H-Pyran, 2,3-dihydro-halogenation, 3, 723 hydroboration, 3, 723 oxepines from, 3, 725 oxidation, 3, 724 reactions, with acids, 3, 723 with carbenes, 3, 725 4H-Pyran, 5,6-dihydro-synthesis, 2, 91 4H-Pyran, 2,6-diphenyl-hydrogenation, 3, 777 4H-Pyran, 6-ethyl-3-vinyl-2,3-dihydro-reactions, with acids, 3, 723 4H-Pyran, 2-methoxy-synthesis, 3, 762 4H-Pyran, 2,4,4,6-tetramethyl-IR spectra, 3, 593 4H-Pyran, 2,4,6-triphenyl-IR spectra, 3, 593... 

Beckmann rearrangement, 3, 710 Pyran-4-carbaldehyde, 2,2-dimethyl-tetrahydro-Reformatsky reaction, 3, 732 4H-Pyran-4-carbaldehydes synthesis, 3, 760-761 Pyran-2-carbonitrile, 5,6-dihydro-reactions, 3, 732... 

H-Pyran-3-carboxylic acid, 6-amino-5-cyano-2,4-diphenyl-ethyl ester... 

H-Pyran-2,6-dicarboxylic acids synthesis, 3, 758 Pyran-2,4-dione, 3,3-dimethyl-photodimerization, 3, 720 reactions... 

Pyran-4-one, 2,2,5-trimethyl-2,3-dihydro-photodimerization, 3, 720 4H-Pyran-4-one, 2,3-dihydro-2,3,5-trimethyl-6-( 1 -methyl-2-oxobutyl)-synthesis, 3, 844 Pyranones alkylation, 2, 56 aromaticity, 3, 632, 633 C NMR, 3, 587, 635 H NMR, 3, 580 cardiac glycosides, 3, 883 chromone synthesis from, 3, 830 colour couplers... 

Oxidation of 4H-pyran-4-thiones with thallium(III) trifluoroacetate was used in the one pot synthesis of l,6-dioxa-6n-thiapentalenes, a hypervalent heterocyclic system [57] (equation 27)... 

A 2,4)6-trisubstituted 2H or 4/f) pyran (38, R = R = Ph) was reported to result in low yield by catalytic reduction of 2,4,6-triphenyl-pyrylium salts by oxidation or by treatment with concentrated sulfuric acid it regenerated the triphenylpyrylium cation. There was no subsequent confirmation of this reaction. The reduction of pyrylium salts with sodium borohydride affords 1,5-diones by way of 4H-pyrans and 2,4-dien-l-ones by way of 2H-pyrans. ... 

Propanol with magnesium in reduction of chlorobenzene, 47, 104 Propionyl fluoride, 46, 6 n Propylamine, 46, 85 n Propylhydrazine, 46, 85 C ( Propyl) N phenylmtrone, genera tion from phenylhydroxylamme and n butyraldehyde, 46, 97 Purification of tetrahydrofuran (Warning), 46,105 4H Pyran 4-one, 2 6 dimethyl 3,5 diphenyl, 47, 54... 

Konjnglerte Dienone und 4H-Pyrane aus Pyrylium-perchloraten allgemeine Arbeitsvorschrift4 0,1 Mol Py-... 

---