Derivatives dimedone

Dimedone derivatives. Dimedone or 6 6-dimethylci/cZohexane-1 3 dioiie j- in saturated aqueous solution J or in 10 per cent. alcohoUc solution gives crystalline derivatives (I) with aldehydes, but not with ketones. The reaction is ... 

To prepare the anhydride , boil a solution of 01 g. of the dimedone derivative (I) in 5 ml. of 80 per cent, ethanol to which 1 drop of concentrated hydrochloric. acid has been added for 5 minutes, than add hot water until the mixture is just turbid, cool and collect the anhydride by filtration. Recrystallise it from dilute methanol. 

Dimedone derivatives. For experimental details, see under Aliphatic Aldehydes, Section 111,70,2. 

Dihydroisoquinoline reacts with the appropriate heterocycle-linked dimedone derivatives to give thiazolo-quinolizinium salts such as 467 <1995RJ0271, 1995DOC776> or pyrazoloquinolizines like 468 <1995RJC146> (Scheme 105). 

The 14C labelled 4-pentenals, 233, have been converted to their dimedone derivatives for radio assay. The lsO-233 has been reduced to 4-pentenol for MS isotopic assay. The average lsO and 14C KIEs in the rearrangement of 232 were found to be ... 

The popularity of Cu(acac)2, where acac = acetylacetonato, as a precatalyst in alkene cyclopropanation using diazoesters has led to the investigation of chiral 1,3-dicarbonyls as a source of asymmetric induction in this process. Mathn et al. (26) report a selective cyclopropanation of styrene with a dimedone-derived diazocarbonyl in the presence of a camphor-derived diketone, Eq. 12. The reaction is con-... 

Prochiral nuclei in the acceptor part can also be used as probes for Case 2 systems, if the donor part is unsymmetrical. An example is given by the dimedone derivative 82, in which the Me groups on the ring have a chemical shift difference... 

Additionally, dimedone derivative 241 and propargylamine 234 could be combined to give the alkynyl vinyl amine 242. The rearrangement/cyclization cascade could be induced upon heating until reflux in chlorobenzene. The an-... 

Reaction of aldoximes with dimedone derivatives under microwave irradiation leads to partially hydrated acridine derivatives . Eused heterocyclic compounds containing partially hydrogenated pyridine and quinoUne rings were prepared by intramolecular cycloaddition reaction of 5-alkynyl oxime derivatives . (Z)-l,10a-Dihydropyrrolo[l,2-i>]... 

Chromophoric derivatives for the optically transparent amino group, such as dimedone derivatives 103-106, were prepared for assigning the absolute configuration of primary and secondary amines. The vinylogous planar amide chromophore (280-290 nm ji — n ... 

The last-mentioned authors22 have described also the oxidation of D-xylo-benzimidazole (XVII) with sodium periodate in 35% ethanol solution. Three molar equivalents of oxidant produced two molar equivalents of formic acid and one of formaldehyde 60% of the latter was isolated as the dimedon derivative. The remainder of the original mole-(31) A. Bistrzycki and G. Przeworski, Ber., 46, 3483 (1912). 

Reaction of acylylides with a 2-(cyclohexadienylidene)dimedone derivative resulted in the formation of a dihydrofuran ring . Furans have been made from reactions of 3-alkylsiloxyallylylides with aldehydes followed by acid hydrolysis of the resultant epoxides . 

Amino acids are quickly deaminated by L-ascorbic acid, leading to browning reactions (66). In the presence of oxygen, iron, and ascorbic acid or DHA, the amino acids gave ammonia, carbon dioxide, and an aldehyde with one carbon less than the original acid (67,68). The aldehydes are isolated as dimedone derivatives and are useful for identification of the amino acids. In the presence of copper and UV light, the deamination is increased. The red color 69-73) formed upon reaction of DHA with amino acids was used for their detection. Recent studies (74-78) of the reaction of DHA with amino acids led to the isolation of a product that changes readily to a novel, stable, free radical species... 

Cycloaddition products 51 were obtained in 64-73% yield from an isocyanide and the acylated dimedone derivative 49 after 24 hours at ambient temperature. ... 

The periodate oxidation of 165 and its derivatives gave 195, which could be transformed into a variety of derivatives (194 and 196) (80MI8) upon reaction with amines, hydrazines, semicarbazide, or thiosemicarbazide (Scheme 44). The thiosemicarbazones 196 were cyclized to the thiadiazoles 199 and thiadiazolines 198, which are of chemotherapeutic interest (80MI8). The aldehyde also affords the expected dimedone derivative 197. 

The diene quickly absorbed 1.96 moles of hydrogen when hydrogenated at room temperature using platinum as a catalyst. Ozonolysis of the diene in dry pentane at -20°, followed by treatment of the reaction mixture with a dilute solution of dimedon provided a 56 percent yield of the dimedon derivative of formaldehyde, m.p. 188.5-190°... 

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