4-Hydrazono

The products obtained in the reaction of A -cyclopropyl-4,5-difluoroanthranilic acid hydrazides 429 with triphosgene were dependent on the steric hindrance imposed by substituent R at position 3, and not the electronic effect of this group. While the unsubstituted compound 429 (R = H) gave exclusively the 4-hydrazono-3,l-benzoxazin-2-one-type product 430, the similar reactions of the chloro-, methyl-, and methoxy-substituted analogs 429 (R = Cl, Me, OMe) resulted in formation of the corresponding quinazoline-2,4-diones 431 as the sole products. For the fluoro-substituted compound 429 (R = F), a 20 80 mixture of the products 430 and 431 was obtained (Equation 46) <2005JHC669>. 

Benzoesaure 4-(Hydrazono-methyl)- -methylester E14b, 490 (aus Aldehyd)... 

From 3-bromo(or chloro)-4-methoxychromen-2-one. Okamoto and co-workers (99JHC767) (Scheme 87) described an efficient method of converting chromen-3-ones 387a,b into 4-bromo(or chloro)-l,2-di-hydro-5-(2-hydroxyphenyl)pyrazol-3-ones 390a,b and 4-hydrazono(or... 

Cyclization of 4-hydrazono-4flr-pyrazol-3-amines with acyl cyanides affords pyrazolo[3,4-t ]-1,2,4-triazine derivatives 2 or products 3,128 depending on the substituent of the starting pyrazole. 

Tetrahydropyrazolo[3,4-e][l,2,4]triazine-3,7-diones via 3>ethoxycarbonylamino-4-hydrazono-5-pyrazolones... 

Isopropylidene and benzylidene hydrazones of selenazole unsubstituted in the 5-position react with p-nitrosodimethylanilines or p-nitrosodiethyl-anilines when heated in organic solvents in the presence of acetic acid or pyridine (49). Highly colored crystalline 2-hydrazono-5-(p-dialkylamino-phenylimino)selenazoles are recovered from the reaction medium (Table X-10). 

Hydrazono-5-(p-dialkylaminophenylimino)seienazoles, pyrazolone azomethin selenazoles, quinoid dyes, and formazans are other important dyes used in photography and the color industry (cf. previous sections). 

Diazonium salt 185 (R = H) when coupled with different CH active compounds yielded 3-hydrazono derivatives (e.g. 186 and 187). Hydrazono derivatives 186 and 187 were cyclized into 3-(l,4-dihydropyridazin-l-yl) 188 and 3-(pyrrolin-l-yl) derivatives 189, respectively (00MI33). 

Hydrazone of 1 -hydrazino-1 -hydroxy-4-phenyl-1,2-dihydro-3//-pyrido [l,2-c]pyrimidin-3-one was patented as cross-linkers for making physiologically compatible and H2O insoluble hydrazine or hydrazono compounds (97JAP(K)97/59303). 

Thiazolo[2,3-c][l,2,4]triazines 658 were prepared (84LA1302) regio-specifically by cyclizing 2-hydrazono-2-thiazoline 659 with glyoxylic acid or ester. They had herbicidal activity. Condensation of 659 with oxamic acid ethyl ester gave hydrazide 660, which was cyclized with sodium... 

Da das eine Wasserstoff-Atom von der Tosyl-hydrazono-Gruppe, das andere vom Hy-drid stammt, eignet sich diese Methode zur Herstellung markierter Kohlenwasserstoffe2 ... 

Auch a-Hydrazono- bzw. a-Hydroximino-alkene lassen sich selektivan der C=C-Dop-pelbindung hydrieren z. B.2 ... 

Aminocarbony]-hydrazono)-l-phenyl- 581 1 - Amino-4,4-diathoxy-1 -phenyl- 363... 

Pyrrolidino-1 -(2-cyan-athyl)- 560 2-Pyrrolidino-l-methyl- 560 Tosylhydrazono- 371 4 -T osylhydrazono -1 - tert. -b u tyl - 36 9 (Tosyl-phenyl-hydrazono)- 368... 

Thioamides react under mild conditions with conjugated azoalkenes (32) to give thiazolines (33) that exhibit hydrazono hydrazino tautomerism. X-ray diffraction studies on (33) showed the compound existed as the hydrazono tautomer <95S1397>. 

Condensation of 9 with ethyl acetoacetate without a solvent gave ethyl 3-(2-(2-(7-hydroxy-2-oxo-2H-chromen-4-yl)-acetyl)hydrazono) butanoate 15 in 48% yield (Scheme 3). 

More recently, asymmetric Mannich-type reactions have been studied in aqueous conditions. Barbas and co-worker reported a direct amino acid catalyzed asymmetric aldol and Mannich-type reactions that can tolerate small amounts of water (<4 vol%).53 Kobayashi found that a diastereo- and enantioselective Mannich-type reaction of a hydrazono ester with silyl enol ethers in aqueous media has been successfully achieved with ZnF2, a chiral diamine ligand, and trifluoromethanesul-fonic acid (Eq. 11.31).54 The diastereoselective Mannich-type reaction... 

A formal enantioselective synthesis of the antibiotic L-azatyrosine was developed. The asymmetric ally lation of hydrazono esters with ally lsilanes in the presence of a catalytic amount of ZnF2-chiral diamines in aqueous media generated (benzoyl)hydrazino-4-pentenoates in high enantioselec-tivity(Eq. 11.46).77... 

Hydrazono derivatives of a thiocarbonyl-1,2,4-triazole have been converted with primary amines into the corresponding thioamides 1-1681... 

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