One-pot enol silane formation-Mukaiyama aldol reactions: Crossed aldehyde-aldehyde coupling, thioester substrates, and reactions in ester solvents
作者:C. Wade Downey、Grant J. Dixon、Jared A. Ingersoll、Claire N. Fuller、Kenneth W. MacCormac、Anna Takashima、Rohina Sediqui
DOI:10.1016/j.tetlet.2019.151192
日期:2019.10
Trimethylsilyl trifluoromethanesulfonate (TMSOTf) and a trialkylamine base promote both in situ enol silane/silyl ketene acetal formation and Mukaiyama aldol addition reactionsbetween a variety of reaction partners in a single reaction flask. Isolation of the required enol silane or silyl ketene acetal is not necessary. For example, crossed aldolreactionsbetween α-disubstituted aldehydes and non-enolizable
Enantioselective Lewis Acid Catalyzed Michael Reactions of Alkylidene Malonates. Catalysis by <i>C</i><sub>2</sub>-Symmetric Bis(oxazoline) Copper(II) Complexes in the Synthesis of Chiral, Differentiated Glutarate Esters
作者:David A. Evans、Tomislav Rovis、Marisa C. Kozlowski、C. Wade Downey、Jason S. Tedrow
DOI:10.1021/ja002246+
日期:2000.9.1
C2-symmetricbis(oxazoline)−Cu(II) complexes 1 catalyze the Mukaiyama Michael reaction of alkylidene malonates and enolsilanes. The use of hexafluoro-2-propanol is essential to induce catalyst turnover. High enantioselectivities are exhibited by bulky alkylidene malonate β-substituents using catalyst 1a. The glutarate ester products are readily decarboxylated to provide chiral 1,5-dicarbonyl synthons
Azetidinone derivatives, a process for their preparation and their use
申请人:Sankyo Company, Limited
公开号:US05856556A1
公开(公告)日:1999-01-05
Compounds of formula (I): ##STR1## (wherein R.sup.1 represents hydrogen or a hydroxy-protecting group, R.sup.2 and R.sup.3 represent hydrogen, alkyl or aryl; R.sup.4 represents optionally substituted alkyl, alicyclic heterocyclic, aryl, aromatic heterocyclic, optionally substituted alkenyl or optionally substituted alkynyl; R.sup.5 represents hydrogen or a carboxy-protecting group; and R.sup.6 represents alkoxy, aryloxy, dialkylamino or diarylamino or two or R.sup.6 together represent o-phenylenedioxy or three together represent CH.sup.3 C(--CH.sub.2 O--).sub.3) may be prepared by reacting the corresponding carbonyl compound with a compound of formula P(R.sup.6).sub.3. Compounds (I) may be cyclised to prepare carbopenem derivatives, many of which have valuable antibiotic activity.
New trialkoxyphosphorane-thiolesters 10, obtained by reaction of oxalimides 9 with trialkyl phosphite, were efficiently cyclized by an intramolecularWittigreaction to give carbapenems 11.
with imidazole, thiazole, and their benzo derivatives in the presence of an alkylchloroformate to give 2-substituted imidazolines and thiazolines in good yields via the intermediacy of unstable N-acylated quaternary salts of azoles. In addition, it was found that silyl enol ethers formed in situ were also useful for the reaction to afford the adducts only by simple sequential addition of five commercially