Pyrazolidinone

C3N2 N N — — — Pyrazole substituted pyrazoles A - and A -pyrazolines pyrazolinones pyrazolidines pyrazolidinones... 

Following the classification of Chapter 4.01, three classes will be considered, (a) Compounds isomeric with aromatic compounds (6), (7) and (8). The quaternary, non-aromatic salts (Scheme 7, Chapter 4.01) will be discussed only in connection with protonation studies which lead to the conclusion of their non-existence. The carbonyl derivatives (9), (10), (13) and (14) will also be included here because it is possible to write an aromatic tautomer for each one, (9 )-(14 ), even if it is energetically unfavoured, (b) Dihydro compounds. In this class not only pyrazolines (15), (16) and (17) but also pyrazolidinones (18) and pyrazolinediones like (1) are included, (c) Tetrahydro compounds. Besides the pyrazolidines (19), the pyrazolidinetriones (2) are included here. 

Sparse data on the pyrazole isomers, pyrazolenines and isopyrazoles, are presented in Table 12. Besides the obvious upheld effect on the chemical shift due to the suppression of the ring current, these compounds behave normally. Data on pyrazolidinones and their salts show the behaviour of cyclic hydrazides (66T2461,67BSF3502). 

The spectra of pyrazolidinones have often been described (63PMH(2)161, 67BSF3502, 70CHE1568). In the l-aryl-3-pyrazolidones (79), both the r (CO) and r (NH) bands changed considerably between the crystal (cyclic dimer) and the solution spectra. Typical values for j (CO) range from 1700 to 1730 cm" in solution. For the l-aryl-5-pyrazolidones (80),... 

Eberle has explored the synthetic possibilities of (421) with aldehydes it leads to hexa-hydropyrimido[i,2-a]indoles (73T4049). Its 5-oxo derivative (l-phenyl-5-pyrazolidinone) has a comparable reactivity (76JOC3775). 

Boyd DB. Application of the hypersurface iterative projection method to bicyclic pyrazolidinone antibacterial agents. J Med Chem 1993 36 1443-9. 

Combinatorial solution-phase cycloadditions of (1Z,4R, 5R )-4-benzoylamino-5-phenylpyrazolidin-3-on-l-azomethine imines 320 to 3-keto esters afforded a library of 26 highly pure bicyclic pyrazolidinones 713 in 6-89% yields and in 14-100% de. Most of the products were isolated as mixtures of the major (13, 23, 3/ , 5/ , 6/ )-epimers 713 and the minor (1R, 2A, 3R, 5R, 6R )-epimers 714 (Scheme 113). Epimerization of these cycloadducts at the anomeric position in solution was confirmed by H NMR spectroscopy <2007MI717>. 

The susceptibility of the sydnone ring to acid-catalyzed hydrolysis at elevated temperature is exploited for the preparation of hydrazines <2000MI227>. Primary amines are first converted to sydnones, which are then hydrolyzed to give hydrazines that may be isolated or reacted further without isolation <1996CHEC-II(4)165>. As masked hydrazines, 3-arylsydnones are firstly subjected to acid-catalyzed ring opening and then allowed to react further in situ with 2-(4-chlorophenyl)hydrazono-3-oxo-butyric acid to form substituted pyrazolidinones (Equation 2) <2005SC2169>. 

J. M. Indelicato, C. E. Pasini, The Acylating Potential of y-Lactam Antibacterials Base Hydrolysis of Bicyclic Pyrazolidinones , J. Med. Chem. 1988, 31, 1227-1230. 

A complete study of the basic hydrolysis of pyrazolidinone (196) by ab initio calculations at RHF/6-31+GV/RHF/6-31-fG" and MP2/6-31-bGV/MP2/6-31- -G levels has been carried out. The alkaline hydrolysis has been studied through a Z ac2 mechanism, characterized by a nucleophilic attack of the hydroxyl group on the carbonyl of the y-lactam ring, formation of the tetrahedral intermediate, and cleavage of the C(2)-N(3) bond to yield the final reaction product. ... 

Solid-state condensation reactions of secondary amines are not yet well developed. However, an interesting condensation of the pyrazolidinone (336) with aromatic aldehydes 77 gives a quantitative access to the azomethinimines 337 by cogrinding and heating to 80 °C [103] (Scheme 53). 

Many photo-induced ring contractions are known. An illustrative example is the isomerization of tetrahydrothiin-4-one into a zwitterion before loss of ethylene (Scheme 30) (70JOC584) pyrazolidinones give (3-lactams (Section 3A2.3.3). 

R are used to control the Amax of the chromophore. Interaction of the dye releaser with ETAox yields the corresponding quinoneimine (84) which is hydrolyzed in alkali to give the sulfamoyl-solubilized yellow image dye (85). Derivatives of l-phenyl-3-pyrazolidinone (see Section 1.14.2.1.4) can function as electron transfer agents. 

Dimethyl acetylenedicarboxylate with several pyrazolidinones (142 R1, R2, R3 = H or alkyl) gives131 the normal Michael adducts 143 and the diazepinones 144 the crystal structure was determined for one diazepinone. 

Keywords pyrazolidinone, benzaldehyde, 1,3-dipol, uncatalyzed, azomethini-mine... 

Organosilicon compounds have also been reacted with thiocarbonyl ylides to afford a variety of heterocycles468,469 and in Section III.F.5 we pointed out the 1,3-dipolar cycloaddition between in situ generated thioaldehydes and a pyrazolidinium ylide to produce a nuclear analogue of pyrazolidinone antibacterial agents332. Moreover, Vedejs has applied the dipolar cycloaddition between a thione, generated from a Norrish-type II fragmenta-... 

Although reaction of 2-substituted 3-pyrazolidinones with acetylenedicarboxylates usually gives ring-expansion products, such as 1,2-diazepines, the treatment of the 2-substituted 3-pyrazolidinone 88 with dialkyl acetylenedi-carboxylate resulted in the formation of a tricyclic compound as the major product, along with the formation of the expected 1,2-diazepine 89, as the minor product <20000L423> (Scheme 18). 

Reagentien mit zwei nucleophilen Zentren konnen mit den Oxazoli-nonen 3 zu cyclischen Verbindungen reagieren. So werden beim Kochen mit Hydrazinhydrat Pyrazolidinone 41,134) und mit Hydroxylamin-... 

Coll M, Frau J, Munoz F, Donoso J. Ab initio study of the basic hydrolysis of the pyrazolidinone ring. J Phys Chem A 1998 102 5915-5922. 

J. Rabiczko and M. Chmielewski, New route to bicyclic pyrazolidinones and hydroxypyrrolidinones from a,/i-unsaturated sugar lactones, J. Org. Chem., 64 (1999) 1347-1351. 

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