Ketones reaction with phosphorous

The N-acylamino ketones (131) can be converted by reaction with phosphorous pentachloride to the chlorimine derivative 135, which undergoes further cyclization to 132 by reaction with hydrazine.219... 

Recently, Xu et al. describled a highly enantioselective Mannich-type three-component reaction of diazoacetophenones 315, alcohols 311, and imines 148 under the cocatalysis of Rh COAc) and phosphoric acid 5 m (Scheme 2.86). In the presence of RhjCOAc), diazoacetophenones and alcohols formed oxonium ylides to serve as the enol equivalents of a-alkoxyl aryl ketones, which then underwent Mannich-type reaction with phosphoric acid-activated imines to produce enantioenriched p-amino-a-hydroxyl ketone products 316 [119],... 

Reactions. Heating an aqueous solution of malonic acid above 70°C results in its decomposition to acetic acid and carbon dioxide. Malonic acid is a useful tool for synthesizing a-unsaturated carboxyUc acids because of its abiUty to undergo decarboxylation and condensation with aldehydes or ketones at the methylene group. Cinnamic acids are formed from the reaction of malonic acid and benzaldehyde derivatives (1). If aUphatic aldehydes are used acryhc acids result (2). Similarly this facile decarboxylation combined with the condensation with an activated double bond yields a-substituted acetic acid derivatives. For example, 4-thiazohdine acetic acids (2) are readily prepared from 2,5-dihydro-l,3-thiazoles (3). A further feature of malonic acid is that it does not form an anhydride when heated with phosphorous pentoxide [1314-56-3] but rather carbon suboxide [504-64-3] [0=C=C=0], a toxic gas that reacts with water to reform malonic acid. 

Myrcene with its conjugated diene system readily undergoes Diels-Alder reactions with a number of dienophiles. For example, reaction with 3-meth.5i-3-pentene-2-one with a catalytic amount of AlCl gives an intermediate monocyclic ketone, which when cyclized with 85% phosphoric acid produces the bicycHc ketone known as Iso E Super [54464-57-2] (49). The product is useful in providing sandalwood-like and cedarwood-like fragrance ingredients (91). 

The acid-catalysed ring-closure of divinyl ketones to cyclopentenones (equation 6), the Nazarov reaction6-8, represents a conrotatory electrocyclization of 4jr-cyclopentadienyl cations. The conrotatory course of the reaction was confirmed for the case of the dicyclo-hexenyl ketone 7, which yielded solely the tricyclic ketone 8 on treatment with phosphoric acid (equation 7)3b. Cycloalkanocyclopentenones 10 with c/s-fused rings are obtained from the trimethylsilyl-substituted ketones 9 (n = 1, 2 or 3) and iron(III) chloride and... 

Primary alkyl halides (chlorides, bromides, and iodides) can be oxidized to aldehydes easily and in good yields with dimethyl sulfoxide.311 Tosyl esters of primary alcohols can be similarly converted to aldehydes,312 and epoxides313 give a-hydroxy ketones or aldehydes.314 The reaction with tosyl esters is an indirect way of oxidizing primary alcohols to aldehydes (9-3). This type of oxidation can also be carried out without isolation of an intermediate ester The alcohol is treated with dimethyl sulfoxide, dicyclohexylcarbodiimide (DCC),315 and anhydrous phosphoric acid.316 In this way a primary alcohol can be converted to the aldehyde with no carboxylic acid being produced. 

Tetrahydrobenzo[6]thiophen-4-one (103) may be prepared from y-(2-thienyl)butyric acid by cyclization with phosphoric acid854 or by Friedel-Crafts cyclization of the corresponding acid chloride.194, 355.358 j s 5-methyl,357 2-ethyl,194 2-isopropyl,358 2- and 3-tert-butyl,359 2,3-dimethyl,360 2-ethyl-3-methyl,360 and 2-bromo 354 derivatives and diethyl 4,5,6,7-tetrahydrobenzo[6]thiophene-4,5-di-carboxylate861 may be prepared similarly. 4,5,6,7-Tetrahydrobenzo-[6]thiophen-7-one (104)357 362,863 and its 5- and 6-methyl 357 and 2-chloro 362 derivatives are obtained from the appropriately substituted y-(3-thienyl)butyric acid, A recent patent 364 describes the vapor phase cyclization of y-(2-thienyl)butyric acid to 103. Ketones (103 and 104) are useful intermediates for the synthesis of 4- and 7-substituted benzo[6]thiophenes, respectively their reactions are discussed in Section VI, B, 4. 

Dehydrative cyclization of 3-(5-carboxy)-5-phenyl-4-(pyrrol-l-yI)l,2,4-triazole (508) with poly phosphoric acid gave (82G345) the 1,2,4-triazolo[3,4-/7]l,3,4-thiadiazine (509). Ring transformation of 1,3,4-oxadiazoles to 7//-l,2,4-triazolo[3,4-/>]l,3,4-thiadiazines (507) was reported by Sasaki et al. (82JOC2757) through the reaction of [(1,3,4-oxadiazol-2-yl)thio]ketones (123) with hydrazine hydrate in the presence of acetic acid. 

Vinyl halides represent yet another important class of intermediates in the conversion of ketones to alkenes. The most widely applied conditions for the conversion of ketones into vinyl halides are those developed by Barton et a/. ° for the conversion of 3p-acetoxyandrost-5-ene-17-one into 3P-hydroxyandrosta-5,16-diene (Scheme 44). These conditions of vinyl halide formation and subsequent reduction have been useful in a number of steroid systems for the introduction of a A -carbon-carbon double bond and have been shown to be compatible with such functional groups as alcohols, isolated double bonds and acetals. The scope of vinyl iodide formation from hydrazones has been studied by Pross and Stemhell, and recently the original reaction conditions were improved by using sterically hindered guanidine bases rather than triethylamine. Haloalkenes have also been prepared from the corresponding ketones by treatment with iodoform and chromium chloride or with phosphorous penta-halides. ... 

A variation of the ketone to alkene transformation is conversion of quinones into arenes, for which a number of reagent systems have been employed. Over a century ago, the reduction of polycyclic quinones to aromatic systems with phosphorous and hydroiodic acid at elevated temperatures was reported. These conditions, however, resulted in complex reaction mixtures consisting of phenols and polyhydrogenated products. More recently, Konieczny and Harvey have reported the reduction of qui-... 

The 3-thietanone 1,1-dioxide structure proposed for the product of the reaction of azibenzil with sulfur dioxide has been shown by nmr spectroscopy to be incorrect.2,2,4,4-Tetramethyl-3-thietanethione 1,1-dioxide is obtained from the corresponding ketone (69% yield) by treatment with phosphorous penta-sulfide.5 ... 

A 1 1 complex of [Eu(fod)3] and Michler s ketone emits red luminescence under daylight illumination.Chemical shifts in the NMR spectra of adducts of [Ln(fod)3(bipy)] and [Ln(fod)3(phen)] are dipolar in origin.[Eu(ttfa)3(phen)] (ttfa = thenoyltrifiuoroacetonate) has been doped into organically modified silicate matrices on reaction with hexamethyldisilazane, a composite phosphor with high emission intensity was formed.The first perfiuoroacetylaceto-nate complexes have been reported. " ... 

Synthesis of fi-ketoallenes and a,fi-unsaturated ketones.1 Isopropenyl methyl ether, under acid catalysis (p-toluenesulfonic acid or phosphoric acid particularly), reacts with a tertiary acetylenic carbinol to give a/3-ketoallene in high yield, as exemplified by the reaction with 3 methylbutyne-l-ol-3 (1). The /3-ketoallene (2) is... 

Condensations of acetophenones with aliphatic aldehydes are often complicated by side reactions, although some simple cases are known to proceed in good yield (e.g. equation 84). An example of the kind of complications that may arise in such cases is seen in the reaction of acetophenone with isobutyr-aldehyde. Base-mediated reaction at low temperature gives a crude aldol that is dehydrated by heating with phosphoric acid to obtain a 3 1 mixture of a,p- and p,7-unsaturated ketones (equation 85). If the reaction is carried out under more traditional conditions, by heating an alcoholic solution of the reactants... 

---