I -0x0y -2 -xanthen y 1 but yric Acid into 2,3 -Benxoxanthone .By A. M. EL-ABBADY, S. AYOUB, and F. G. BADDAR.y-Oxo-y-2-xanthenylbutyric acid has been reduced to y-Z-xanthenylbutyric acid and then cyclised to 1',2',3',4'-tetrahydro-4'-0~0-2,3-benzoxanthen. This is reduced to 1',2',3',4'-tetrahydro-2,3-benzoxanthen, then dehydrogenated, and oxidised to 2,3-benzoxanthone. y-2-Xanthenylbutyric ester has been condensed with diethyl oxalate, and the oxalyl derivative cyclised to 1',2'-dihydro-Z,3-benzoxanthen-3',4'-dicarboxylic anhydride. This on dehydrogenation, decarboxylation, and oxidation gives 2,3-benzoxanthone.CONTRARY to a report by Burtner and Brown1 the Friedel-Crafts reaction of xanthen with succinic anhydride in benzene gave a mixture of y-oxo-y-2-xanthenylbutyric acid (I) and p-benzoylpropionic acid. However, condensation in acetylene tetrachloride afforded the keto-acid (I) in 96% yield. The structure of this keto-acid was established by its oxidation to xanthone-2-carboxylic acid (XIII) . Mild oxidation of either y-oxo-y-2xanthenylbutyric acid (I) or its methyl ester by potassium permanganate in aqueous acetone yielded y-oxo-y-2-xanthonylbutyric acid (11; R = H) or its methyl ester respectively. Hydrolysis of the diketo-ester (11; R = Me) with 5% alcoholic potassium hydroxide gave the diketo-acid (11; R = H), but treatment with 10% aqueous sodium hydroxide led to a phenolic acid. This was probably due to the rupture of the heterocyclic ring, to give ~-(4-hydroxy-3-o-hydroxybenzoylbenzoyl)propionic acid (111). Its structure was based on the fact that it cyclised back to the original ester (11; R = Me) on attempted methylation with methyl sulphate and potassium carbonate in acetone. A similar result was obtained with 2,Z'-dihydroxybenzophenone, which was converted into xanthone on attempted methylation with alkaline methyl sulphate 3a or on evaporation of its alkaline solution.36The structure of the acid (111) was further supported by its infrared spectrum. It showed a broad band a t 3200-3125 and a weak sharp band a t 3545 cm.-l (in CHClJ, characteristic for the chelated and the free OH group, respective1y.b Two bands a t 1695 and 1639 cm.-l (in Nujol) are characteristic for the side chain and the o-hydroxycarbonyl group, respectively.& Reduction of y-oxoy-2-xanthenylbutyric acid (I) by Clemmensen's method, or less satisfactorily by the Wolff-Kishner method, gave y-2-xanthenylbutyric acid (IV; R = H).Conversion of the acid (V; R = H) into 2,3-benzoxanthone (XIV) was carried out by two routes: ( A ) The acid chloride of (IV; R = H) was best cyclised with anhydrous stannic chloride, affording a cyclic ketone, theoretically of structure (VII) or (XV). It was proved

Durch Kondensation der β‐Aroylpropionsäuren (I) mit Isatin (II) unter den Bedingungen der Perkin‐Reaktion werden in 46‐68%iger Ausbeute die Butenolide (III) erhalten, aus denen durch saure Hydrolyse in 84‐92%iger Ausbeute die Butenolide (IV) entstehen.

No abstract

No abstract

2-Methyl cyclohexanone is condensed with dimethyl succinate in the presence of potassium tertiary butoxide giving a solid mixture of isomers of the corresponding alkylidene and alkenyl half-esters. On alkaline hydrolysis this gives a-carboxy-!3-(2-methyl cyclohex-1-eny1)propionic acid. The keto-ester obtained by cyclization of the half-ester yielded the corresponding unsaturated ketone after acid hydrolysis and decarboxylation. Reduction of the keto-ester affords the corresponding a,a-unsaturated ester. Both the unsaturated ketone and ester are easily hydrogenated in the presence of platinum oxide to the corresponding saturated ketone and ester.Canadian Journal of Chemistry, 47, 1483 (1969) Cook and Phillip (I), and Chatterjee and Bhattacharyya (2) reported the Stobbt condensation of 2-methyl cyclohexanone with diethyl and dimethyl succinate respectively in the presence of potassium t-butoxide. They obtained the half-ester, P-carbethoxy-P-(2-methyl cyclohex-1-eny1)propionic acid (lc; R = C2H5) as a solid, and P-carbmethoxy-P-(2-methyl cyclohex-1-eny1)propionic acid (lc; R = CH,) as an oil.In the present investigation the above reaction was repeated for further study and for the preparation of a methyl perhydroindane nucleus which can be regarded as an intermediate for the synthesis of steroid-like compounds.2-Methyl cyclohexanone was condensed with dimethyl succinate in the presence of potassium t-butoxide (3) to yield the corresponding halfester as an oil. The yield was found to be greatly increased (from 71 % (2) to 90%) by increasing the molality of potassium t-butoxide. This oil solidified and was found to be a mixture of isomers (la, lb, and l c ; R = CH,). The ultraviolet (u.v.) absorption spectrum showed one strong band at 225 mp (E 10 OOO), characteristic of a,P-unsaturated esters (see ref. 4, p. 32). This indicated the presence of the half-ester (la; R = CH,) as one isomer of the mixture. It seems that this isomer is present in a small amount as indicated by the low value of the molecular extinction coefficient. Moreover, no 2-methyl cyclohexanone could be isolated from a mild oxidation of the half-ester mixture using alkaline permanganate at room temperature, but instead a neutral carbonyl compound was obtained which gave a 2,4-dinitrophenyl hydrazone. This substance is still under investigation.Repeating the oxidation at 0" failed to give any neutral carbonyl substance. The infrared (i.r.) spectrum of the half-ester showed 'bands at 2800-2500 (w), 1750 (s), 935 (v), and 810 (s) cm-l, characteristic of the stretching frequencies of hydroxyl and carbonyl groups of saturated acids and esters, the hydroxyl deformation (out of plane) of acids, and the CH (out of plane) deformation vibrations of trisubstituted alkenes respectively (5). These vibrations strongly suggest the presence of the isomer (lb; R = CH,). Finally the nuclear magnetic resonance (n.m.r.) spectrum showed signals at 1.6 and 5.1 p.p.m. (6), characteristic of a methyl group attached to an unconjugated double bond and a vinyl proton respec...

In a preliminary communication (1, 2) the reaction of two representative ketones, benzophenone and fluorenone, with diethyl methylsuccinate in the presence of sodiunl ethoxide was shown to proceed by a Stobbe condensation giving the expected half-esters in good yields. In the present work we are reporting an extension of this study on both aldehydes and ketones. Benzaldehyde, o-methoxybenzaldehyde, p-chlorobenzaldehyde, benzophenone, and acetophenone were condensed with dimethyl methylsuccinate in the presence of potassium tert-butoxide (3); froin the products were formed anhydrides, half-esters, indones, and naphthalene derivatives. In all these reactions, exact parallels were found with the corresponding products previously obtained from ethyl succinate itself (3).Good yields (60-72%) of the P-half-esters (11) were obtained from the condensation of benzaldehyde, o-methoxybenzaldehyde, benzophenone, and acetophenone. However, the yield was only poor, as expected, with p-chlorobenzaldehyde, but a shorter period of reflux was found to increase this yield slightly and minimize resinification. In the case of acetophenone, the isomeric P-half-ester (VI; R = CH3) was also obtained and separated.The condensation of the aldehydes in general afforded, in addition to the expected half-esters, varying amounts of the corresponding itaconic acids. o-Methoxybenzaldehyde gave also a small amount of an acidic non-ketonic substance, m.p. 217", which was found to be the lactonic acid (IX). The constitution of (IX) as 2-o-anisyl-3-carboxy-4-o-methoxybenzylidene-3-methyl-5-oxotetrahydrofuran follows from the following observations: (a) the infrared spectrum (KBr) showed a strong band a t 1750 cm-I, characteristic of the stretching frequencies of carbonyl groups of a,punsaturated-y-lactones (4) and (b) alkaline hydrolysis of the substance gave the itaconic acid (11; R1 = R3 = Rq = H, Rz = CH3O) and o-methoxybenzaldehyde which was characterized as the 2,4-dinitrophenylhydrazone. Analogs of (IX) have frequently been observed in the condensations of ethyl succinate with aromatic aldehydes. The formation of this lactonic acid a t high temperature is evidence for (a) the relative stability of the intermediate paraconic ester (3) towards the tert-butoxide ions; and (b) the comparative reactivity of o-methoxybenzaldehyde. When o-rnethoxybenzaldehyde was condensed with dimethyl methylsuccinate in the presence of sodium ethoxide a t -15O, the lactonic acid (IX) was obtained as the main product.

No abstract

No abstract