2-aryl-l,3-diones

Biocidal 2-aryl-l,3-diones and their enol esters showing acaricidal and pre-and postemergence herbicidal activity were reported since the mid-1970 s as exemplified by 3-hydroxy-2-arylindones from Union Carbide [1], 3-Aryl-pyrrolidine-... 

Over a decade ago, 2-aryl-l,3-diones emerged in the literature as a new, weakly active class of ACC inhibitors [6]. Recently, pinoxaden was reported as a novel cereal graminidde that belongs to this class [7]. 

The first 2-aryl-l,3-diones (ADs) were reported in 1977 by Wheeler (Union carbide) [58]. He claimed biocidal aryl-cyclohexenyl esters 1, 2 (Fig. 9.4) with pre-and post-emergence herbicidal effects and miticidal activity against Tetranychus urticae. 

The 2-aryl-l,3-diones can be separated into three parts for the analysis of the structure-activity relationships, namely the aryl-, the dione with its procidal forms... 

In the case of a diketone (e.g., 3-tosyloxypentane-2,4-dione), the formation of 5-acetyl-4-methyl-2-aryl-l,3-thiazole derivatives can be realized in very good yields (86-89%) (Scheme 7). All these experiments where performed in a Sears Kenmore unmodified household microwave oven (990 W) equipped with a turntable. The average bulk temperature was estimated by inserting a thermometer in the alumina bath housing the reaction vessel. 

Rh2(OAc)4-catalyzed decomposition of 2-diazocyclohexane-l,3-dione 380a or its 5,5-dimethyl derivate 380b in the presence of an aryl iodide leads to an iodonium ylide 381 355). The mild reaction conditions unique to the rhodium catalyst are essential to the successful isolation of the ylide which rearranges to 382 under the more forcing conditions required upon copper catalysis (copper bronze, Cu(acac)2, CuCl2) 355). 

In the early 1970 s potent acaricidal activity in 3-aryl-4-hy-droxy-coumarins. III, and 2-aryl-l,3-indanediones, IV, and their enol esters was discovered at Union Carbide (1,2). Extensive synthesis and screening of analogs in the dione and enol ester series led to the field test candidates Va and Vb, active against both motile forms (mite) and eggs. Va and Vb embodied certain structural and physicochemical features shown by published QSAR studies (2,3) to be important in determining the level of activity in the 1,3-indanedione series (1) the dimension D2 across the aryl ring must be near 7A and symmetry is preferred (2) the... 

The use of a pyrimidine precursor continues to be the more popular approach to furo pyrimidines. The one-pot three-component condensation reactions of alkyl or aryl isocyanides with A[A -dimethylbarbituric acid in the presence of terephthaldialdehyde proceeded spontaneously at room temperature in DMF to give good yields of the corresponding l,4-bis(6-alkyl or arylamino-1,3-dimethylfurano[2,3-4]pyrimidin-2,4(l//,3//)-dione-5-yl)benzenes <2006BMCL3697>. 

In DMF containing lithium perchlorate, reduction of o -bromopropiophenone at mercury gives l,4-diphenyl-2,3-dimethylbutan-l,4-dione in 65% yield [236]. However, electrolysis of a-bromopropiophenone in the presence of benzoyl chloride affords only l,3-diphenyl-2-methylpropan-l,3-dione. Other studies involving reduction of phenacyl bromides include the electrosynthesis of 4-aryl-2-methylfurans [237] and the regioselective synthesis of enol carbonates [238] semicarbazones of phenacyl bromide can be converted into 3,7-diaryl-2/7-imidazo[2,l-Z>][l,3,4]oxadiazines [239]. Reduction of 1,2-dibenzoyl-chloroethane at mercury in DMF containing lithium perchlorate affords mixtures of phenyl tribenzoyl cyclopentanols and diphenyl dibenzoyl butanediones [240]. 

Deprotonation of the 4-amino group in 4-(arylamino)nicotinic esters with sodium hydride and subsequent conversion to a urea with allyl isocyanate yields an intermediate urea, whose cyclization furnishes the corresponding l-aryl-3-allylpyrido[4,3-r/jpyrimidine-2,4(l//,3//)-dione 12.498... 

The fourth method consisted in conversion of l,3-dialkyl-7-aryloxazolo[2,3-/]-purine-2,4(l //,3//)-diones 57 with sodium sulfide to l,3-dialkyl-7-aryl-thiazolo[2,3-/]purine-2,4(177,3/7)-diones 60 (cf. Scheme 16) (90KGS1396). 

Fuchs elegant approach to the morphinan skeleton utilized an intramolecular conjugate addition/alkylation sequence, in which connections C12-C13 and C9-C14 were formed as a result of one tandem process.73-74 Mitsunobu condensation between alcohol 164 (from 2-allylcyclohexene-l,3-dione in five steps and 43% overall yield) and phenol 163 (from isovanilline in 6 steps and overall yield of 40%)73c gave the ether 165, Scheme 19. TBDMS deprotection followed by an oxidation/reduction sequence set the aryl ether... 

The two rotamers can be detected by comparing experimental dipole moments with calculated values (see Piazza et al., 1968, Sorriso and Foffani, 1973, and the summary by Sorriso, 1978, p. 120). By using this method, Nikolaev and Popik (1989b) found that l-aryl-3-methyl-2-diazo-l,3-diones undergo a (Z,E) E,E)... 

This approach has also been utilised in an enantioselective approach to generate axially chiral diaryl phenols using bmcine as the enatiomerically pure amine base at low temperatures of -20 to -40 °C [87]. The phenols could be obtained in up to 83 % ee. Aryllead triacetates can also be used to arylate [)-diketones. Both linear and cyclic P-diketones with an a-substituent already present could be successfully arylated with a variety of aryllead triacetates. The P-diketone 2-methylcyclohexane-l,3-dione... 

N-aryl-1,2-diamines 43, 728 (Z)-2-Alkylideneindan-l,3-dione monoketals 43,637 2-Alkylideneindan-l,3-diones... 

Low-pressure (10 —10 Torr) gas-phase pyrolysis ( 650°C) of 3-phenylpropargyl acetate or benzoate (196) gives the corresponding alkyl or aryl phenyl-2-methylene-l,3-dione (197) in good yieldthe proposed... 

H,3H- Pyrrolo[l, 2-c]oxazole-l, 3-dione, 5,6,7,8-tetrahydro-IR spectra, 6, 978 [2.2](2,5)Pyrrolophane, N-aryl-rearrangements, 4, 209 Pyrrolophanes natural products, 7, 764 synthesis, 7, 771 Pyrrolophanes, N-aryl-synthesis, 7, 774 (2,4)Pyrrolophanes synthesis, 7, 771 Pyrrolo[3,4-c]pyran-4-ones synthesis, 4, 288 Pyrrolopyrans synthesis, 4, 525, 526 Pyrrolopyrazines synthesis, 4, 526 Pyrrolo[l, 2-a]pyrazines synthesis, 4, 516 Pyrrolo[2,3-6]pyrazines Mannich reaction, 4, 504 Vilsmeier reaction, 4, 505 Pyrrolo[3,4-c]pyrazole, 1,3a,6,6a-tetrahydro-structure, 6, 976 synthesis, 6, 1019 Pyrrolopyrazoles synthesis, 5, 164 Pyrrolo[l,2-6]pyrazoles synthesis, 6, 1002, 1006 Pyrrolo[3,4-c]pyrazoles reactions, 6, 1034 synthesis, 6, 989, 1043 Pyrrolo[3,4-c]pyrazolones synthesis, 6, 989 Pyrfolopyridazines synthesis, 4, 517 Pyrrolo[l, 2-6]pyridazines synthesis, 4, 297 6/7-Pyrrolo[2,3-d]pyridazines synthesis, 4, 291 2/f-Pyrrolo[3,4-d]pyridazines synthesis, 4, 291 6/7-Pyrrolo[3,4-d]pyridazines synthesis, 4, 291... 

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