52216-89-4Relevant academic research and scientific papers
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.
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.
