Cyclohexane-l,3-dione

SCHULZ A, CRT o, BEYER P and KLEINIG H (1993) SC-0051, a 2-benzoyl-cyclohexane-l,3-dione bleaching herbicide, is a potent inhibitor of the enzyme /<-hydroxyphenylpyruvate dioxygenase , Terr, 318, 162-6. 

The reaction of the O-alkylated cyclohexan-l,3-diones 73 with p-substituted anilines in the presence of acetic acid is influenced by the nature of R in 73, yielding 4-anilinoxanthones 74 when R = H, but the condensed y-lactams 75 when R = Me (Scheme 51) <00T5947>. 

Several syntheses of 2//-pyrans are based on the preparation of the acyclic precursors (157b) in the hope that the dienone zZ 2//-pyran equilibrium will favor the heterocycle (157a). Often the product will contain both valence isomers. Such dienone precursors can be obtained by Knoevenagel condensation of 1,3-dicarbonyl compounds with a,(3-unsaturated aldehydes (Scheme 57). Simple 1,3-diketones yield the 2//-pyran directly (88IZV1815) and cyclohexan-l,3-diones afford fused pyrans (82S683, 84JHC913, 87JOC1972>. 

When 2-(3-phenylprop-2-ynyl)cyclohexane-l,3-dione is heated with zinc carbonate, ring closure to a fused 4//-pyran occurs (62AP645). If the triple bond is terminal, cyclization leads to a furan derivative. Under the same conditions, the analogous acyclic diketones do not yield pyrans. 

Scheme 7.39 Preparation of resin bound cyclohexan-l,3-dione (CHD resin).

Grant, P. T., Middleton, C., Plack, P. A., and Thomson, R. H., The isolation of four aminocyclohex-enimines (mycosporines) and a structurally related derivative of cyclohexane-l 3-dione (gadusol) from the brine shrimp, Artemia, Comp. Biochem. Physiol., 80B, 755, 1985. 

Cyclohexan-l,3-dion addiert sich photochemisch an Acrylsauremethyl-ester zu den Cyclooctan-Derivaten 87a und 87 b (150). 

The cyclization of 2-(l,3-diaryl-3-oxopropyl)cyclohexan-l,3-diones to cyclohexcno[A]thiopyrylium salts by H2S generated in situ from ZnS and acid is only successful with electron-rich aryl substituents. It is suggested that the reaction proceeds through the cyclohexeno[2 ]-4//-thiopyran which is produced in the absence of donor substituents and which yields the thiopyrylium salt on treatment with HCIO4 (Scheme 234) <2000CHE1032>. 

Dihydroquinoline-5-ones are obtained by cyclocondensation of 3-aminoacroleins with cyclohexan-l,3-diones or 3-ethoxyacrylaldehydes and aminocyclohexenone. The corresponding ketone (R1 = Me) behaves analogously235 (equation 169). The unexpected pattern of the quinoline substitution therefore can be reasonably ascribed to intermediate transamination between the 1,3-dicarbonyl components. 

Enaminones derived from cyclohexan-l,3-dione were treated with a variety of reducing agents176, with the aim of obtaining amino alcohols. While metal hydrides were inefficient and hydrogenation over Pd produced fragmentation, Raney nickel furnished the desired products in fairly good yields (Scheme 123). 

Following the same strategy, Tu and co-workers [112] have reported a rapid and direct method for the synthesis of highly functionalized acridine-1,8(2//,5/1)-diones 109 in excellent yields. They employed a multicomponent protocol to a 5-substituted-cyclohexane-l,3-dione, an aldehyde and an enaminone to get the... 

A very simple triketone has proven useful for treating the rare genetic disease tyrosinemia. The drug alternately known as nitisinone (30) or orfadin actually hears a very close relation to a pesticide. The analogue in which methylsulfonyl replaces the trifluoromethyl group, mesotrione, is an important corn herbicide. Acylation of cyclohexan-l,3-dione, shown as an enol (28) with acid chloride (29), leads in a single step to 30. ... 

The reduced acridinediones are also produced when cyclohexan-l,3-diones react with a 3-amino-2-alkyl-acrolein, involving the loss of a carbon atom, possibly as formic acid. 7,8-Dil droquinolin-5(6H)-ones are also formed (J.V. Greenhill et al, J. chem. Research (M), 1981, 0821). 

Cyclohexane-l,3-dione [504-02-9] M 112.1, m 107-108 , pKf 5.25. Crystallise the dione from benzene. Dissolve 50g of the diol in 140mL of C6H6 under N2, cool, collect the solid and dry it in a vacuum desiccator overnight. It is unstable and should be stored under N2 or Ar at 0 . [Thompson Org Synth Coll Vol III 278 1955, Beilstein 7 IV 1985.]... 

The second synthesis was a brief, six-step synthesis of iVa-benzyl-aspidospermidine (505), from the amine 506, which was readily prepared from A -benzylaniline and cyclohexan-l,3-dione (298,299). A double alkylation of506gave the intermediate 507, which was cyclized by photochemical means to a mixture of epimers of the hexahydrocarbazolone 508, which contains a irons B/C ring junction. However, alkylation of the derived anion... 

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