58442-48-1

Upstream product

• 59-88-1 phenylhydrazine hydrochloride 
• 220715-99-1 (Z)-4-Amino-5-methyl-hex-3-en-2-one 
• 75624-68-9 (5-Methyl-2,4-dioxohexyl)triphenylphosphonium-chlorid 
• 75624-69-0 (E)-5-Methoxy-2-methyl-6-(triphenyl-λ⁵-phosphanylidene)-hex-4-en-3-one 
• 75624-87-2 (5-Isopropyl-2-phenyl-2H-pyrazol-3-ylmethyl)-triphenyl-phosphonium; chloride 

Relevant academic research and scientific papers

Scope and limitations in the regioselective synthesis of 1,3,5-trisubstituted pyrazoles from β-amino enones and hydrazine derivatives. 13C-chemical shift prediction rules for 1,3,5-trisubstituted pyrazoles

β-amino enones react with hydrazine derivatives to give regioselectively 1,3,5-trisubstituted pyrazoles. The synthetic method only presents limitations when the β-substituent of the enone and the hydrazine substituent are bulky or possess an electron withdrawing character. Comparison of the 13C-NMR spectra of the seventy pyrazoles allowed us to estimate a 13C-chemical shift prediction rule for 1,3,5-trisubstituted pyrazoles, with deviations of less than ± 1 ppm.

Reactions with Organophosphorus Compounds, XLVI. Reactivity Umpolung of 1,3-Dioxo Compounds through Introduction of a Triphenylphosphonio Group. - Regioselective Syntheses of Isoxazoles and Pyrazoles from (2,4-Dioxoalkyl)triphenylphosphonium Salts

Phosphonium salts 2 and 6, upon deprotonation with BuLi and subsequent reaction with acyl halides, yield the γ-acyl derivatives 3 and 7, respectively, which on treatment with hydrochloric acid afford the corresponding (dioxoalkyl)phosphonium salts 4 and 8.Isoxazole derivatives 9 and 10 are formed regioselectivly from 4 and 8 with NH2OH*HCl, while with R-NH-NH2*HCl (R = H or C6H5) the pyrazole-containing phosphonium salts 14 and 15 are obtained in an analogous reaction.In each case the direction of cyclisation is different to the reactions of the corresponding non-phosphorus substituted 1,3-dioxo compounds.On treatment with aqueous NaOH 9 and 10 are cleaved to triphenylphosphane oxide and isoxazoles 11 and 12, while 14 and 15 yield the pyrazoles 16 and 17.Wittig reaction of 9a or 14a with aldehydes or ketones leads to the isoxazole olefins 13 or the pyrazole olefins 18, respectively.