19620-37-2Relevant academic research and scientific papers
Selective Base-free Transfer Hydrogenation of α,β-Unsaturated Carbonyl Compounds using iPrOH or EtOH as Hydrogen Source
Farrar-Tobar, Ronald A.,Wei, Zhihong,Jiao, Haijun,Hinze, Sandra,de Vries, Johannes G.
supporting information, p. 2725 - 2734 (2018/02/28)
Commercially available Ru-MACHOTM-BH is an active catalyst for the hydrogenation of several functional groups and for the dehydrogenation of alcohols. Herein, we report on the new application of this catalyst to the base-free transfer hydrogenation of carbonyl compounds. Ru-MACHOTM-BH proved to be highly active and selective in this transformation, even with α,β-unsaturated carbonyl compounds as substrates. The corresponding aliphatic, aromatic and allylic alcohols were obtained in excellent yields with catalyst loadings as low as 0.1–0.5 mol % at mild temperatures after very short reaction times. This protocol tolerates iPrOH and EtOH as hydrogen sources. Additionally, scale up to multi-gram amounts was performed without any loss of activity or selectivity. An outer-sphere mechanism has been proposed and the computed kinetics and thermodynamics of crotonaldehyde and 1-phenyl-but-2-en-one are in perfect agreement with the experiment.
Lipase-catalyzed asymmetric synthesis of (R)- and (S)-4-tert-butyldimethylsilyloxy-2,6,6-trimethyl-2-cyclohexenone and their dihydro derivatives
Tanaka,Yamamoto,Oritani
, p. 1273 - 1278 (2007/10/03)
Racemic 4-hydroxy-2,6,6-trimethyl-2-cyclohexenone, trans- and cis-2,6,6-trimethyl-2-cyclohexene-1,4-diols were prepared by reduction of 4-oxoisophorone with sodium borohydride-cerium chloride. Lipase (PS-30)-catalyzed kinetic resolution of (±)-cis-2,6,6-trimethyl-2-cyclohexene-1,4-diol with vinyl acetate led to (1R, 4S)-4-acetoxy-2,6,6-trimethyl-2-cyclohexen-1-ol (81%ee) and (1S,4R)-1-acetoxy-2,6,6-trimethyl-2-cyclohexene-4-ol (92%ee). Hydrolysis of the former monoacetate and recrystallization of the resulting material afforded enantiomerically pure (1R, 4S)-2,6,6-trimethyl-2-cyclohexene-1,4-diol. On the other hand, recrystallization of (1S,4R) monoacetate itself provided an optically pure sample, which was then hydrolyzed to give (1S, 4R)-2,6,6-trimethylcyclohexene-1,4-diol. Transformation of both diols into (S)- and (R)-4-tert-butyldimethylsilyloxy-2,6,6-trimethyl-2-cyclohexenone was conducted in two steps including silylation and oxidation. Catalytic hydrogenation of these (S)- and (R)-silyloxy enones over Raney nickel afforded the corresponding dihydro derivatives.
A New Access to 2,6,6-Trimethylcyclohexa-2,4-dienone from 4-Oxoisophorone
Soukup, Milan,Lukac, Teodor,Zell, Reinhard,Roessler, Felix,Steiner, Kurt,Widmer, Erich
, p. 365 - 369 (2007/10/02)
2,6,6-Trimethylcyclohexa-2,4-dienone (1), a versatile starting material for the preparation of some carotenoids and several natural products, was efficiently (73 percent yield) prepared from oxoisophorone 3.After conversion of 3 to the alcohol 4 or the acetate 5, H2O was eliminated (4 -> 1) under acidic distillative conditions, whereas AcOH could be eliminated (5 -> 1) under Pd(O) catalysis.
SYNTHESIS OF CYCLIC α'α'-DISUBSTITUTED-α-ALKYL-γ-HYDROXY-α,β-ENONES FROM α-PHENYLTHIO-α,β-ENONES
Jarowcki, Krzysztof
, p. 607 - 612 (2007/10/02)
Key reactions in a "two pot" synthesis of cyclic γ-hydroxy-α,β-enones (6) from α-phenylthioenones (1) are regioselective α-alkylation of the α-phenylthioenones (1) and sigmatropic rearrangement of the sulphoxide (3).
The Catalytic Reduction of Aldehydes and Ketones with 2-Propanol over Hydrous Zirconium Oxide
Shibagaki, Makoto,Takahashi, Kyoko,Matasushita, Hajime
, p. 3283 - 3288 (2007/10/02)
Reduction of aldehydes with 2-propanol proceeded efficiently by catalysis with hydrous zirconium oxide to give the corresponding alcohols.Most ketones also were reduced efficiently, but conjugated or sterically hindered ketones resisted the reduction.The reduction was carried out with primary, secondary, or tertiary alcohols, and only secondary alcohols served as hydrogen donors.Kinetic experiments have indicated that the reaction rate is first-order dependence on each of the concentrations of the carbonyl compound, 2-propanol, and the catalyst.An observation of the primary isotope effect has suggested that a step of hydride transfer from absorbed 2-propanol to absorbed carbonyl compound constitutes the rate-determining step for the reduction.
Identification of New Constituents of Quince Fruit Flavor (Cydonia oblo ga Mill. = C. vulgaris Pers.)
Ishihara, Masakazu,Tsuneya, Tomoyuki,Shiota, Haruyasu,Shiga, Minoru
, p. 491 - 495 (2007/10/02)
As a flavor of quince fruit, four new bicyclononanes, 2,2,6,7-tetramethylbicyclonona-4,7,9(1)-triene (1), (+)-2,2,6,7-tetramethylbicyclonona-4,9(1)-dien-8-one (2), (-)-2,2,6,7-tetramethylbicyclonona-4,9(1)-dien-8-ol (3), and (-)-2,2,6,7-tetramethylbicyclonona-4,9(1)-diene-7,8-diol (4), have been identified.Racemic compounds 1-4 have been synthesized from 4-oxoisophorone by direct and regioselective reduction to 4-hydroxy-2,6,6-trimethyl-2-cyclohexen-1-one followed by ketal Claisen rearrangement. 3,4-Didehydro-β-ionol (5) has also bee n found to be one of the constituents of quince fruit oil.
Photochemical Reactions. 145th Communication. Carbonyl vs. Epoxyketone Photochemistry: Photolysis of 1,2;3,4-Diepoxy-2,6,6-trimethyl-1-cyclohexyl Methyl Ketone
Phaff, Rox,Bischofberger, Norbert,Mathies, Peter,Petter, Walter,Frei, Bruno,Jeger, Oskar
, p. 1204 - 1216 (2007/10/02)
The synthesis and photolysis of the title compound 3 is described.Irradiation (λ > 280 nm, MeCN) of the di-epoxyketone 3 leads predominantly to γ-H abstraction.Cyclization furnishes the cyclobutanols 22-24, while cleavage gives compound 25, presumably via the allene-oxide intermediate 36.Further, products 27 and 28 are formed by Norrish fragmentation and by initial cleavage of the C(α)-O bond of the oxirane, respectively.The structures of the products 22-25, 27, and 28 were assigned on the basis of the spectral data of the photolysis products of the 13C-labelled diepoxyketone -3 and by X-ray analysis of the compounds 24 and 35, the latter being the p-nitrobenzoate of 22.
