15790-85-9Relevant academic research and scientific papers
Use of an Aminosilyllithium for the Diastereoselective Synthesis of Diphenyl Oxasilacyclopentane Acetals and Polyols
Tenenbaum, Jason M.,Woerpel
, p. 4325 - 4327 (2003)
(Equation presented) The conjugate addition reaction of a stable, in situ generated silyllithium gives a β-hydroxysilyl ester with high diastereoselectivity. Conversion of the β-hydroxysilyl ester to a β-fluorosilyl ester affords the precursor to the oxasilacyclopentane acetal in high yields under mild conditions. A hydride reduction and subsequent intramolecular silylation lead to the acetal in excellent yields. Finally, highly selective nucleophilic substitution affords oxasilacyclopentanes, which undergo a mild oxidation to afford 1,3-trans diols with high selectivity.
Stereocontrol of the Horner-Wadsworth-Emmons Reaction: Application to the Synthesis of HIV-1 Protease Inhibitors
Martyn, Derek C.,Hoult, Deborah A.,Abell, Andrew D.
, p. 391 - 396 (2007/10/03)
A systematic study on the Horner-Wadsworth-Emmons (HWE) reaction has shown that ethyl diphenylphosphonoacetate and methyl diphenylphosphonoacetate give a high excess of (Z)-alkenes. These reaction conditions were then used to prepare (Z)-ethyl-5-phenylpent-2-enoate, the corresponding (E)-isomer being prepared by standard Wittig chemistry. Reduction of each allylic ester, with diisobutylaluminium hydride (DIBAL), gave the allylic alcohols (15) and (19), respectively. Epoxidation of (15) and (19), under Sharpless conditions, gave separate samples of all four stereoisomers of 2,3-epoxy-5-phenylpentan-1-ol. Esterification of each isomer with Cbz-valine, under Mitsunobu conditions, provided (9)-(12) which were assayed against HIV protease. The cis series (9)-(10) proved to be significantly more potent than the trans (11)-12) and, within each of these series, the isomers derived from L-diisopropyltartrate [(9) and (11)] were the most active.
AN IMPROVED PROCEDURE FOR THE TWO CARBON HOMOLOGATION OF ESTERS TO α,β-UNSATURATED ESTERS
Takacs, James M.,Helle, Mark A.,Seely, Franklin L.
, p. 1257 - 1260 (2007/10/02)
Treatment of esters with diisobutylaluminium hydride (DIBAL) in the presence of lithio-trialkylphosphonoacetate results in improved yields of the homologated α,β-unsaturated esters.The problematic overreduction, which has previously observed in the half reduction of esters using DIBAL, is minimal (3percent) under these conditions.
HORNER-WADSWORTH-EMMONS REACTION: USE OF LITHIUM CHLORIDE AND AN AMINE FOR BASE-SENSITIVE COMPOUNDS
Blanchette, Mary A.,Choy, William,Davis, Jeffery T.,Essenfeld, Amy P.,Masamune, Satoru,et al.
, p. 2183 - 2186 (2007/10/02)
A mild olefination procedure, utilizing LiCl and an amine, has been developed for use with base-sensitive aldehydes and phosphonates.
THE EFFECT OF THE PHOSPHORYL SUBSTITUENTS ON THE STEREOCHEMISTRY OF THE HORNER REACTION
Larsen, Rolf Olaf,Aksnes,Gunnar
, p. 339 - 344 (2007/10/02)
The stereochemistry of the olefin forming reaction of various phosphoryl stabilized carbanions and aldehydes in ethanol is reported.The aromatic aldehydes react with acyclic phosphoryl stabilized carbanions yielding the trans isomers stereoselectively, whereas the 5- and 6-membered cyclic phosphonates (II and III) resulted in high yields of cis isomeric olefins.The aliphatic aldehydes give rise to considerable amounts of cis olefins also, decreasing in the series phosphonates, phosphinates and phosphine oxides, respectively.The stereochemical results are discussed in terms of pentacoordinated reaction intermediates.
Stereochemistry of the Reaction of Diorganocuprate(I) Complexes Derived from Grignard Reagents with α,β-Acetylenic Esters
Jalander, Lars,Iambolieva, Kostadinka,Sundstroem, Viola
, p. 715 - 720 (2007/10/02)
Diorganocuprate(I) complexes RCH3CuMgX, prepared from methylcopper and Grignard reagents (i-PrMgBr and t-BuMgCl) gave mainly cis-1,4-addition of the alkyl group originally present in the Grignard reagents and small amounts of cis- and trans-1,4-addition of the methyl group introduced by methylcopper, when they were allowed to react with ethyl propiolate and ethyl phenylpropiolate.The proportion of cis-1,4-addition products did not change when the reaction temperature was raised from -78 deg C to room temperature.The configurations of the main reaction products from the reaction with ethyl phenylpropiolate, ethyl (Z)-β-isopropylcinnamate and ethyl (Z)-β-t-butylcinnamate, were established by conversion of the corresponding acids to β-isopropylindenone and β-t-butylindenone.
