Aryl hydrazid

A vinyl ether and an aryl hydrazide react to give compound 72 (83JHC1657). A large number of compounds have been made from a,P-unsaturated nitriles. Crotononitriles react with A-acetylcyanoacetohydrazide and with cyanocinna-monitrile to give compounds such as 73 (91GEP3926770), and compound 74 (90JOC2259), respectively. 

Nitro- -athylester 214 4-Nitro- -aryldiazenid 568 4-Nitro- -(2-aryl-hydrazid) 568... 

Aryl hydrazide linker 38 stable to both acid and base was utilized in SPPS [46], Treatment of the resin with a copper(II) catalyst in the presence of a base and nucleophile gave the corresponding acid, amide, or ester (Scheme 13). 

Aryl hydrazide-based linker 79 was developed as a traceless handle that released products under mild oxidative conditions (Scheme 42) [91]. Polymeric bound p-iodophenylhydrazide was subjected to a variety of Pd°-catalyzed coupling reactions (Heck, Suzuki, Sonogashira, and Stille). Oxidation with Cu(OAc)2 in MeOH and pyridine released the final products in 50-96% yield. 

Millington CR, Quarrell R, Lowe G. Aryl hydrazides as linkers for solid phase synthesis which are cleavable under mild oxidative conditions. Tetrahedron Lett 1998 39 7201-7204. 

Acyl hydrazides are useful precursors for the synthesis of 1,2,4-triazoles. Reaction of acyl hydrazides 149 with imidoylbenzotriazoles 148 in the presence of catalytic amounts of acetic acid under microwave irradiation afforded 3,4,5-trisubstituted triazoles 150 <06JOC9051>. Treatment of A-substituted acetamides with oxalyl chloride generated imidoyl chlorides, which reacted readily with aryl hydrazides to give 3-aryl-5-methyl-4-substituted[ 1,2,4]triazoles <06SC2217>. 5-Methyl triazoles could be further functionalized through a-lithiation and subsequent reaction with electrophiles. ( )-A -(Ethoxymethylene)hydrazinecarboxylic acid methyl ester 152 was applied to the one-pot synthesis of 4-substituted-2,4-dihydro-3//-1,2,4-triazolin-3-ones 153 from readily available primary alkyl and aryl amines 151 <06TL6743>. An efficient synthesis of substituted 1,2,4-triazoles involved condensation of benzoylhydrazides with thioamides under microwave irradiation <06JCR293>. 

Amino-1,3,4-oxadiazolei3b- 55.- 0,02 mol Thiokohlensaure-(2-aryl-hydrazid)-imid-methylester erwarmt man aufeinem Olbad zwisehen 180-220°. Es setzt eine intensive Fmtwicklung von Methanthiol ein t Abzug ), wobei das Produkt zusammensintert. Nach 20 min ist die Reaktion beendet und man kann die erhaltene Substanz umkristallisieren. 

Powell J.H. and Gannett, P.M. (2002) Mechanisms of carcinogenicity of aryl hydrazines, aryl hydrazides, and arene diazoniumions./. Environ. Pathol. Toxicol. Oncol., 21 (1), 1-31. 

Coupling of a few aliphatic diazonium compounds to aromatic rings has been reported. All the examples reported so far involve cyclopropanediazonium ions and bridgehead diazonium ions, in which loss of N2 would lead to very unstable carbocations. ° Azobenzenes have been prepared by Pd-catalyzed coupling of aryl hydrazides with aryl halides, followed by direct oxidation. ... 

The principle of this linker is based on an oxidative cleavage of aryl hydrazides, and it has been successfully used in the synthesis of peptides [144]. The linker system is stable under acidic and basic conditions, and may be modified as shown for 126 so as to allow the synthesis of combinatorial compounds 127 in a traceless manner, as outlined in Scheme 60 [145]. 

Af-Aroylisothiazolium imines 230 are prepared by cyclocondensation of thiocyano-butenals 227 with aryl hydrazides 228 <05H(65)2705>. These imines are oxidized, and the resulting hydroperoxy sultams are reduced to give hydroxysultams 231. Under thermal conditions, these sultams undergo dehydration followed by 1,5-electrocyclization to give a novel series of heteropentalenes, the oxadiazolo-sultams 233. 

Abweichend von dem allgemein bei der Hantzsch-Synthese beobachteten Reaktionsablauf wird bei der Umsetzung von Thiokohlensaure-amid-(2-aryl-hydraziden) mit 1-Ethoxy-1,2-dichlor-ethan kein Primarangriff am Thiokohlensaure-S-Atom, sondern am N-Atom beobachtet. Die dadurch gebildeten Thiokohlensaure-(2-aryl-hydrazid)-(2-chlor-ethylidenamide) lassen sich leicht zu den entsprechenden 1,3-Thiazolen cyclisieren344 z.B. ... 

Ebenfalls unter intramolekularer Alkylierung verlauft die Bildung von 2-(2-Aryl-hydrazi-no)-l,3-thiazolen aus Thiokohlensaure-(2-aryl-hydrazid)-(2-chlor-ethylidenamiden)344. 

Acyl-hydrazono)-3-amino-propansiiure-ester cyclisieren bei Natriumethanolat-Einwirkung bereits bci 20c zu l-Acy1-3-amino-5-hydroxy-lH-pyrazolen1178 und Malonsaure-l-(2-aryl-hydrazid)-3-ethyl-ester-l-imid-Hydrochloride geben 3-Amino-l-aryl-5-hydroxy-lH-pyrazole427. 

Aryl hydrazides such as ArNiBociN B0CNHNH2)." A phosphine-free cauly 1,3-bis(2,6-diisopropylpheny 1 )imidazob this additive becomes ligated to the Pd 1... 

Recently, syntheses have been developed that avoid the reactive and difficult to access amidrazones. Benzo- and pyrido-fused 1,2,4-triazinyls were prepared via the N -(het)aryl-N -[2-nitro(het)aryl]hydrazides 24 that can be prepared by N -(2-nitroarylation) of easily prepared N -(het)arylhy-drazides. Mild reduction of the nitro group followed by an acid-mediated... 

Levenberg, B. Isolation and structure of agaritine, a y-glutamyl-substituted aryl-hydrazide derivative from Agaricaceae. J. Biol. Chem. 239, 2267 (1964). 

Kang s regioselective [5,5]-sigmatropic rearrangement reactions of aryl hydrazides... 

Microwave assisted reaction of 2-diazo, 4,4-trifluoro-3-oxobutanoate 37 with aryl hydrazides in the presence of copper(II)acetate, followed by reaction with ammonium acetate in acetic acid gave the 1,2,4-triazines 38 in modest yield (Scheme 17) [27],... 

SCHEME 3.92 Copper-catalyzed synthesis of 3-aminopyrazoles from aryl hydrazides [95]. 

C]purines such as [ " CJgriseolic acid diester 135 in about 29% yield and, in 59% yield the [ CJimidazodiazepinone derivative 136. an intermediate in the synthesis of [ C]-pentostatin. Lastly, one example has been reported demonstrating that this type of reaction may be extended to other, appropriately 1,2-, 1,3- or 1,4-functionalized substrates thus, condensation of triethyl orthoformate with a highly substituted aryl hydrazide furnished 2-aryl substituted [5- C] 1,3,4-oxadiazole 137 in a low, but useful radiochemical yield of 10% l... 

Others Aryl hydrazide hnker Peptide amines or esters o H ... 

Woo Y-H, Mitchell AR Camarero JA (2007) The use of aryl hydrazide linkers for the solid phase synthesis of chemically modified peptides. Int J Pept Res Ther 13 181-190... 

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