866-71-7Relevant academic research and scientific papers
The chemoselective cyclisation of unsymmetrical γ-diketones to cyclopentenones by ditected aldol reaction using a magnesium chelate
Cadman, Michael L. F.,Crombie, Leslie,Freeman, Stephen,Mistry, Jayshree
, p. 1397 - 1408 (2007/10/02)
The feasibility of synthesising disubstituted cyclopent-2-enones chemoselectively from unsymmetrical γ-diketones, using an aldol reaction directed by magnesium chelation, has been studied.Treatment of 3,3-dimethylhexane-2,5-dione 15 with aqueous sodium hydroxide (0.5 mol dm-3) gives a mixture of 3,5,5-trimethyl- 12 and 3,4,4-trimethylcyclopent-2-enone 14 in an isomer ratio 2.2:1.Insertion of an α-methoxycarbonyl grouping as a control element allows formation of a magnesium chelate 17 when treated with magnesium methoxide, and the major product is then mainly the undehydrated aldol 21.This, when treated with aqueous sodium hydroxide (0.5 mol dm-3) to dehydrate, hydrolyse and decarboxylate, gives the 3,5,5-trimethyl- and 3,4,4-trimethylcyclopent-2-enones in a nearly chemospecific ratio of 1:49.When 3-methoxycarbonyl-4,4-dimethylhexane-2,5-dione 16 is treated with aqueous sodium hydroxide (0.5 mol dm-3), omitting the magnesium methoxide treatment, the corresponding ratio of cyclopentenones was still an interesting 1:7.3.Treatment with sodium methoxide in methanol gives, by contrast γ-lactone 27.Treatment of undecane-4,7-dione 34 with aqueous sodium hydroxide (0.5 mol dm-3) at reflux gives 2,3-dipropylcyclopent-2-enone 36 and 3-butyl-2-ethylcyclopent-2-enones 35 in a ratio of almost 1:1.Treatment of 6-methoxycarbonylundecane-4,7-dione 33 with magnesium methoxide in methanol gives undehydrated aldol which when treated with aqueous sodium hydroxide gives the dipropylcyclopent-2-enone 36 and 3-butyl-2-ethylcyclopent-2-enones 35 in 9:1 ratio.Conversely, the 5-methoxycarbonyldione 32 gives a corresponding ratio of 36 to 35 of 1:9.The best ratios attained, 1:15 for 36 and 35 from 32 and 20:1 for 36 and 35 from 33, were when magnesium methoxide in refluxing benzene or toluene were employed.There is still a strong chemoselective effect when the magnesium treatment is omitted.Preliminary examination of the corresponding cyclohex-2-enone systems gave poorer chemoselectivities when either procedure was employed. 6-Methoxycarbonyldodecane-5,9-dione 52 gave 2,3-dipropyl-54 and 3-butyl-2-ethyl-cyclohex-2-enone 55 in a ratio of ca. 4:1 whilst the 5-methoxycarbonyldodecane-4,8-dione 53 gave a 1: ca. 4 ratio.
Study of photochemical addition of acyl radical to electron-deficient olefins
Macias,Molinillo,Massanet,Rodriguez-Luis
, p. 3345 - 3352 (2007/10/02)
The photochemical addition of acyl radical to electron-deficient olefins is studied. The scope of the reaction, the mechanism, the role that molecular oxygen plays, the influence of steric effects, and the side reaction that take place are discussed. The reaction was carried out using a range of electron-withdrawing substituents (ketones, amides, lactones, nitrile and esters) with good yields of the corresponding photoadduct in all cases.
Synthesis and Chemistry of Azolenines. Part 16. Preparation of both 3H- and 2H-Pyrroles from 2,2-Disubstituted 1,4-Diketones via the Paal-Knorr Reaction, and Isolation of Intermediate 2-Hydroxy-3,4-dihydro-2H-pyrroles
Lui, Kon-Hung,Sammes, Michael P.
, p. 457 - 468 (2007/10/02)
Treatment of 2,2-disubstituted 1,4-diketones (1) with liquid ammonia gives high yields of isolable isomeric 2-hydroxy-3,4-dihydro-2H-pyrroles (10) and (11), many of which may be dehydrated to 3H-pyrroles (2) together, in certain cases, with isomeric methylene-pyrrolines (14) and (15).When heated in acetic acid with ammonium acetate, the diketones (1) yield 2H-pyrroles (18), sometimes in admixture with 3H-pyrroles (2) from which they are formed by rearrangement.The diketones (1), including some novel examples, are prepared from nitro-ketones (6) by the Nef reaction, as well as other methods.
An efficient and mild entry to 1,4-dicarbonyl compounds via photochemical addition of acyl radical to electron-deficient olefins
Macias, Francisco A.,Molinillo, Jose Maria G.,Collado, Isidro G.,Massanet, Guillermo M.,Rodriguez-Luis, Francisco
, p. 3063 - 3066 (2007/10/02)
Photoehcmical addition of acetaldehyde to electron-deficient olefins in the presence of molecular oxygen provides an efficient and mild method for the synthesis of 1,4-functionallzed compounds. Some considerations about the mechanism and the substituent effects are outlined.
2-Ethoxy-2-propenyl Diethyl Phosphate. An Efficient Halo Acetone Equivalent for the Pd-Catalyzed Cross-coupling with Tin Enolates
Kosugi, Masanori,Ohashi, Kenji,Akuzawa, Kazuko,Kawazoe, Takashi,Sano, Hiroshi,Migita, Toshihoko
, p. 1237 - 1238 (2007/10/02)
In the presence of Pd(0) complexes, 2-ethoxy-2-propenyl diethyl phosphate was found to react with organotins to give the corresponding coupling products, showing to be a more efficient halo acetone equivalent compared with the corresponding acetate or carbonate.Reaction with tin enolates gave the 1,4-diketone in moderate to good yields.
(Phosphine)carbonylnitrosylacylcobaltate Complexes as Acyl Transfer Reagents. Acylation of Allylic Halides, Conjugated Enones, and Quinones
Hegedus, Louis S.,Perry, Robert J.
, p. 4955 - 4960 (2007/10/02)
The complex Co(NO)(CO)2(PPh3) is an air stable, easily handled crystalline solid, prepared from Co2(CO)8, sodium nitrite, and triphenylphosphine without isolation of the volatile intermediate Co(NO)(CO)3.Treatment of this complex with organolithium reagents at -40 deg C generated unstable acylate complexes - which readily transferred the acyl group to allylic halides to produce β,γ-unsaturated ketones, to conjugated ketones to produce 1,4-dicarbonyl compounds, and to quinones to form 4-acylcyclohexadienones.
