58775-66-9Relevant academic research and scientific papers
Different Reaction Modes for the Oxidative Dimerization of Epoxyquinols and Epoxyquinones. Importance of Intermolecular Hydrogen-Bonding
Shoji, Mitsuru,Imai, Hiroki,Shiina, Isamu,Kakeya, Hideaki,Osada, Hiroyuki,Hayashi, Yujiro
, p. 1548 - 1556 (2007/10/03)
An oxidative dimerization reaction, involving the three successive steps of oxidation, 6π-electrocyclization, and Diels-Alder reaction, has been experimentally and theoretically investigated for the three 2-alkenyl-3-hydroxymethyl-2-cyclohexen-1-one deriv
A tandem Horner-Emmons olefination-gonjugate addition approach to the synthesis of 1,5-Disubstituted-6-azabicyclo[3.2.1]octanes based on the AE ring structure of the norditerpenoid alkaloid methyllycaconitine
Callis, David J.,Thomas, Noel F.,Pearson, David P. J.,Potter, Barry V. L.
, p. 4634 - 4640 (2007/10/03)
A novel Horner-Emmons olefination conjugate addition reaction of N-acetylamides to form 1,5-disubstituted-6-azabicyclo[3.2.1]octanes with two bridgehead quarternary carbon centers is reported. This reaction is a key step in an approach to the synthesis of small ring analogues based on the AE ring structure of the Delphinium norditerpenoid, methyllycaconitine (MLA) (1). Initially, 3-(hydroxymethyl)cyclohex-2-en-1-one (10) was selected as the starting material to these structures, but its generation proved inefficient. In contrast, the synthesis of 3-[(phenylthio)methyl]cyclohex-2-en-1-one (6) and 3-(1,3-dithian-2-yl)cyclohex-2-en-1-one (11) proceeded in good yield. Subsequent hydrocyanation, ketalization, reduction, acetylation, deprotection of the acetal, and Horner-Emmons olefination-conjugate addition reaction to form 1-[(phenylthio)methyl]-5-[(ethoxycarbonyl)methyl]-6-acetamido-6-azabicyclo[3.2. 1]octane(28), 1-(1,3-dithian-2-yl)-5-[(ethoxycarbonyl)methyl]-6-acetyl-6-azabicyclo[3.2.1] octane (29), respectively, are reported, as well as for readily available 3-methylcyclohex-2-en-1-one (12). Studies on the Pummerer rearrangement of 28 and subsequent desulfurization and reduction to form an hydroxymethyl-substituted azabicyclo[3.2.1.]octane (40) and then selective protection to form a protected hydroxyethyl N-ethyl (hydroxymethyl)azabicyclo-[3.2.1]octane (3) are also described.
Oxidative Rearrangement of Sulfur-Containing Tertiary Allylic Alcohols: Synthesis of 2-Cycloalkenones Bearing 3- and 3- Substituents
Luzzio, Frederick A.,Moore, William J.
, p. 2966 - 2971 (2007/10/02)
Substrate 1--2-cycloalkenols 3a-d and 1-cyclohexenols 1a-d were prepared by adding lithium and 2-lithio-2-alkyl-1,3-dithianes, respectively, in the 1,2-mode to various 2-cycloalkenones.The ranges of yields for the additions were 86-95percent in the (phenylthio)methyl series and 69-88percent in the dithiane series.A representative compound from each range of substrate tertiary allylic alcohols was then treated with a series of oxochromium(VI)-amine reagents such as pyridinium chlorochromate (PCC), pyridinium dichromate (PDC), the Collins reagent (CrO3*Pyr2), and 2,2'-bipyridinium ch lorochromate (BPCC).The oxochromium(VI)-amine reagents effected conversions of the representative substrates to the corresponding 3-- and 3--2-cycloalkenones 4a-d and 2a-d which were measured by gas chromatographic-mass spectral analysis.When comparing the efficiency of the range of oxochromium(VI)-amine reagents, PCC was found to give the best conversions to the corresponding transposed α,β-unsaturated carbonyl compounds in both series of substrates, while the Jones reagent gave only decomposed material and no recovery of substrate.Distinct improvements on the initial PCC protocol using silica gel as an in situ adsorbent and promotion by ultrasound were then established with a range of substrate tertiary allylic alcohols while comparing sonicated versus nonsonicated experiments.The isolated yields of transposed products were found to be increased as much as 60percent in the dithiane series and 9percent in the (phenylthio)methyl series with the application of high-intensity ultrasound.Prolonged exposure of the substrate (3a) in the (phenylthio)methyl series to the PCC/silica reagent system resulted in the recovery of the corresponding sulfone (5), the identity o f which was confirmed by selective oxidation of the transposed enone (4a) with m-chloroperbenzoic acid.
Reactions of Lithium Bicyclobutan-2-olates Formed by Carbenoid Type Decomposition of Lithiothioacetal Enolates. A Novel Concept for One-Pot Cyclopropanation of Enones
Ramig, Keith,Bhupathy, M.,Cohen, Theodore
, p. 4404 - 4412 (2007/10/02)
A new cyclopropanation procedure for α,β-unsaturated ketones is based upon the low-temperature decomposition of enolate carbenoids generated by conjugate addition of tris(phenylthio)methyllithium to α,β-unsaturated ketones followed by lithium/phenylthio e
