52216-90-7Relevant academic research and scientific papers
Temperature effects on stereocontrol in the Horner-Wadsworth-Emmons condensation of α-phosphono lactones
Yu, Jose S.,Wiemer, David F.
, p. 6263 - 6265 (2007)
(Chemical Equation Presented) The Horner-Wadsworth-Emmons condensation of some α-phosphono lactones has been examined for conditions that impact product stereochemistry. The temperature employed to quench the reaction was found to be a major factor. For example, after the diethyl phosphonate derivative of γ-butyrolactone was treated with potassium hexamethyldisilazane, 18-crown-6, and propionaldehyde at -78°C in THF, an aliquot transferred to a flask at ～30°C gave almost exclusively the Z-olefin product, while one allowed to warm to room temperature over several hours greatly favored the E-olefin.
Asymmetric Hydrogenation of Olefins with Aprotic Oxygen Functionalities Catalyzed by BINAP-Ru(II) Complexes
Ohta, Tetsuo,Miyake, Tsutomu,Seido, Nobuo,Kumobayashi, Hidenori,Takaya, Hidemasa
, p. 357 - 363 (2007/10/02)
Cyclic α,β-unsaturated ketones, alkylidene lactones, and alkenyl ethers have been hydrogenated in high enantiomeric excesses by use of BINAP-Ru(II) complexes (BINAP = 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl) as catalysts. 2-Alkylidenecyclopentanones were hydrogenated in the presence of Cl, Ru2Cl4(BINAP)2(NEt3), or Ru(OCOCH3)2(BINAP) in up to 98percent ee, while in the case of 2-benzylidene- and 2-(3-phenylpropylidene)cyclopentanones, enantiomeric excesses of the hydrogenation were below 50percent under the same conditions.The sense of asymmetric induction as well as the enantioselectivity (95percent ee) obtained in the hydrogenation of (E)-2-propylidene-γ-butyrolactone were the same as those of the (Z)-isomer.Lactones, 2- and 4-alkylidene-γ-butyrolactones, were converted to the corresponding saturated γ-butyrolactones in 95percent ee.Hydrogenation of diketene with the catalytic system derived from (benzene)>Cl and triethylamine or complex Ru2Cl42(NEt3) established a new synthetic route to (R)-4-methyl-2-oxetanone, a promising monomer of biodegradable polymers, in up to 97percent selectivity and 92percent ee.Alkenyl ethers, 2-methylenetetrahydrofuran, and 2-methyl-3,4-dihydrofuran have also been hydrogenated to give 2-methyltetrahydrofuran in 91 and 87percent ee, respectively.
Stereocontrol in Horner-Wadsworth-Emmons Condensations of α-Phosphono Lactones with Aldehydes: A Synthesis of Integerrinecic Acid and Senecic Acid Lactones
Lee, Koo,Jackson, John A.,Wiemer, David F.
, p. 5967 - 5971 (2007/10/02)
The Horner-Wadsworth-Emmons condensations of α-phosphono lactones were investigated under a variety of conditions.Upon treatment with KHMDS and 18-crown-6 in THF, condensations of the five-membered ring phosphono lactones 7a and 8 with propionaldehyde afforded the E olefins cleanly.In contrast, these phosphonates gave predominantly the Z olefins upon treatment with propionaldehyde, K2CO3 and 18-crown-6 in THF.A similar, though somewhat less-pronounced trend was observed with the six-membered ring phosphono lactone 9a.However, in its condensation with acetaldehyde the more functionalized phosphono lactone 4 gave the best E selectivity (ca. 9:1) when DBU/CH3CN was used, providing the methyl ester of integerrinecic acid lactone (5) in 77percent isolated yield.When K2CO3/18-crown-6/toluene was employed in a parallel reaction, only slight selectivity for the Z isomer was observed, but the methyl ester of senecic acid lactone (6) still was obtained in 43-46percent yield from the product mixture.
Stereoselective Synthesis of (E)- or (Z)-α-Alkylidene-γ-butyrolactone from γ-Butyrolactone and Bis Disulfide and Mechanistic Studies of the Effect of Metal Complexes on the Stereoselection
Matsui, Syuichi
, p. 1853 - 1866 (2007/10/02)
Treatment of γ-butyrolactone with bis disulfide in presence of 2.2. equiv of lithium diisopropylamide (LDA) produced lithium enolate of O-ethyl S-(tetrahydro-2-oxo-3-furanyl) dithiocarbonate, which reacted with an aldehyde to afford exclusively (E)-α-alkylidene-γ-butyrolactone.Interestingly, when the reaction was quenched below -20 deg C or when it was carried out in the presence of metal complex such as zinc chloride, copper(I) iodide, or tributyltin chloride, (Z)-α-alkylidene-γ-butyrolactone was obtained as the major product.The stereoselectivity of this reaction was sensitive to the reaction temperature and the metal cation employed.
A New Synthesis of α-Methylene Lactones
Murray, Alistair W.,Reid, Robert G.
, p. 132 - 133 (2007/10/02)
The α-formylation of γ- and δ-lactones and the high yield conversion into their respective α-methylene γ- and δ-lactones are described.
A Specific and Efficient Synthesis of (+/-)-Dihydrocorynantheol
Danieli, Bruno,Lesma, Giordano,Palmisano, Giovanni,Tollari, Stefano
, p. 1237 - 1240 (2007/10/02)
A specific and efficient synthesis of (+/-)-dihydrocorynantheol (1) is reported.Starting with the easily accessible imine (3), ring D was built via stereoselective reaction with the lactone (4a), thus providing the complete carbon skeleton of (1); subsequ
New Methods for Stereoselective Synthesis of α-Alkylidene-γ-butyrolactones Using Monoanion of O-Ethyl S-(Tetrahydro-2-oxo-3-furanyl) Thiocarbonate and Dianion of α-Mercapto-γ-butyrolactone
Tanaka, Kazuhiko,Uneme, Hideki,Yamagishi, Nobuyuki,Tanikaga, Rikuhei,Kaji, Aritsune
, p. 2910 - 2916 (2007/10/02)
The lithium enolates of O-ethyl S-(tetrahydro-2-oxo-3-furanyl) dithiocarbonate and thiocarbonate were found to be efficient reagents for the stereoselective synthesis of α-alkylidene-γ-butyrolactones from carbonyl compounds.The dianion of α-mercapto-γ-butyrolactone was successfully generated by treatment of α-mercapto-γ-butyrolactone with 2.2 equivalents of lithium diisopropylamide in the presence of N,N,N',N'-tetramethylethylenediamine at -78 deg C in THF.The dianion thus formed has been utilized for the efficient and stereoselective synthesis of α-alkylidene-γ-butyrolactones from carbonyl compounds.
Synthesis of alkyl substituted α,β unsaturated γ lactones as potential antitumor agents
Howie,Manni,Cassady
, p. 840 - 843 (2007/10/07)
A series of alkyl substituted di and monolactones including (E,E) 3,3 (alkanediylidene)bis[dihydro 2(3H) furanones] and the monolactones was synthesized by reaction of α (triphenylphosphoranylidene) γ butyrolactone with appropriate aldehydes. The reaction of this ylide with formaldehyde gave α methylene γ butyrolactone. These compounds were tested for antitumor activity as part of a study to determine the influence of β substituents and distance between alkylating sites on the antitumor activity of α,β unsaturated lactones. The testing was carried out in standard National Cancer Institute screens and the compounds possessed ED50 values of 16 to 110 μg/ml against cells derived from human carcinoma of the nasopharynx (KB) and were inactive against L1210 lymphoid leukemia in the mouse.
