Y?-Dioxo compounds

Torgov introduced an important variation of the Michael addition allylic alcohols are used as vinylogous a -synthons and 1,3-dioxo compounds as d -reagents (S.N. Ananchenko, 1962, 1963 H. Smith, 1964 C. Rufer) 1967). Mild reaction conditions have been successful in the addition of ],3-dioxo compounds to vinyl ketones. Potassium fluoride can act as weakly basic, non-nudeophilic catalyst in such Michael additions under essentially non-acidic and non-basic conditions (Y. Kitabara, 1964). 

The addition of large enolate synthons to cyclohexenone derivatives via Michael addition leads to equatorial substitution. If the cyclohexenone conformation is fixed, e.g. as in decalones or steroids, the addition is highly stereoselective. This is also the case with the S-addition to conjugated dienones (Y. Abe, 1956). Large substituents at C-4 of cyclic a -synthons direct incoming carbanions to the /rans-position at C-3 (A.R. Battersby, 1960). The thermodynamically most stable products are formed in these cases, because the addition of 1,3-dioxo compounds to activated double bonds is essentially reversible. 

The lithium enolate of AUV-dimethylacetamide underwent addition to 2-aryl-1-nitroethenes to give /faryl-y-nitroamides. The lithium dianions and the trianions of /l-oxo esters and /i,y-dioxo esters undergo addition to 2-aryl-1-nitroethenes to give bicyclic compounds as a single dia-stereomer8. 

Dioxo-4.5-dime thy l-bexahydro-[imidazolo-4,.5 4 5-imidazol, f. y and 3.y-Diureylen-butan This compound can be nitrated to a di-nitro deriv. See /9,y-Diurelylen-butan and Derivatives... 

Sorm and Beranek39 used an intramolecular acylation in their synthesis of l-azoniumtricyclo[3.3.3.0]undecane (66). Condensation of nitromethane with acrylonitrile in the presence of an alkaline catalyst resulted in the formation of tris-(2-cyanoethyl)nitromethane (60), which afforded the triethyl ester 61 on hydrolysis followed by esterification. The ester was reduced catalytically to give a pyrrolidone (62). The derivative (62) gave rise to 8-(j8-carboethoxyethyl)-3,5-dioxo-pyrrolizidine (63) on heating. Reduction of 63 resulted in the formation of 8-(y-hydroxypropyl)pyrrolizidine (64). Replacement of the hydroxy group by bromine (65), followed by cyclization, afforded the tricyclic compound 66. 

A sigruficant use is as a catalyst in a multitude of reactions, such as the formation of acrjdic and methacrjdic acid amides from fatty acid amides (81) of cychc ketones such as 4-phen5icyclopentane-l,2-dione and 2,5-dihydroxy-/)-benzoquinone from benzaldehyde diethji acetal and 2,4-dioxo-5,5-dimethoxy-hexanoic acid methyl ester (82) of dimer aldehydes from propane (83) and for the polymerization of epoxy compounds (84). Mag nesium Kthylate. Magnesium ethoxide [2414-98-4]y Mg(OC2H 2 niol wt 114.4, is an almost white hygroscopic powder density,... 

These include the SSA-catalyzed synthesis of heterocyclic compounds such as xanthenes, coumarins, oxazoles, and so on. Xanthenes are of great therapeutic and biological interest on account of their many biological activities such as anti-inflanunatory, antiviral, antibacterial properties, and so on. Seyyed Hamzeh et al. (2008) carried out the SSA-catalyzed synthesis of aryl-14 f-dibenzo[fl,y]xanthenes from aldehydes and P-naphthol and 1,8-dioxo-octahydro-xanthenes from aldehydes and 1,3-dicarbonyl componnd such as dimedone under solvent-free conditions (Schemes 5.25, 5.26). Reactions were carried out at 80°C. Nazeruddin et al. (2011) documented an effective method for 9,10-dihydro-12-aryl-8 f-benzo[a]xanthenes-ll(12 f)-one derivatives in excellent yield and short reaction time using SSA under solvent-free conditions (Scheme 5.27). 

A mixture of dry Pb-tetraacetate and Ga-carbonate refluxed briefly in abs. benzene, cooled, 3,17-dioxo-19-hydroxy-Zl -androslene added, and refluxed 14 hrs. 3,17-dioxo-10j -aceloxy-zj -estrene. Y 77%. based on startg. m. consumed.—The reaction is critically influenced by the choice of the solvent and independent of steric factors. It makes available by straightforward synthesis compounds which otherwise can be obtained only by multi-step procedures. F. e. s. M. Amorosa et al., Helv. 45, 2674 (1962) without CaCOg cf. F. Alvarez, Steroids 3, 13 (1964). 

X = 0, Y = S). Hydrolysis of the latter gives 3,6-dioxo[8](2,5)thienophane (91), whose dynamic properties, i.e. ring versus chair flipping, have been investigated by variable-temperature n.m.r. spectroscopy.The preparation of paracyclo-furano- and -thieno-phanes (92 X = O or S) and of the multi-layered compounds (93 and 94 X = O or S) has been described the electronic spectra of... 

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