By designing a novel chiral ion-pair organocatalyst composed of chiral phosphate and DABCO-derived quaternary ammonium, highly enantioselective 3-
exo
iodo-cycloetherification of allyl alcohols was ...achieved using NIS as a halogen source. Based on this reaction, one-pot asymmetric 3-
exo
iodo-cycloetherification/Wagner-Meerwein rearrangement of allyl alcohols en route to enantioenriched 2-iodomethyl-2-aryl cycloalkanones was subsequently developed. Due to the participation of adjacent iodine, the Wagner-Meerwein rearrangement of 2-iodomethyl-2-aryl epoxide proceeds with unusual retention of stereoconfiguration.
Enantioselective 3-
exo
iodo-cycloetherification of allyl alcohols was realized by employing a novel ion-pair organocatalyst.
Enantioselective 3-
exo
iodo-cycloetherification of allyl alcohols was realized by employing a novel ion-pair organocatalyst.
By designing a novel chiral ion-pair organocatalyst composed of chiral ...phosphate and DABCO-derived quaternary ammonium, highly enantioselective 3-
exo
iodo-cycloetherification of allyl alcohols was achieved using NIS as a halogen source. Based on this reaction, one-pot asymmetric 3-
exo
iodo-cycloetherification/Wagner–Meerwein rearrangement of allyl alcohols en route to enantioenriched 2-iodomethyl-2-aryl cycloalkanones was subsequently developed. Due to the participation of adjacent iodine, the Wagner–Meerwein rearrangement of 2-iodomethyl-2-aryl epoxide proceeds with unusual retention of stereoconfiguration.
A novel oxidative rearrangement of malondialdehyde was described. Under the effect of H 2 O 2 , malondialdehyde smoothly transferred to carboxylic acid with C–C bond cleavage in good to excellent ...yields. Mechanistic studies showed that this reaction proceeded via the formation of a 1,2-dioxolane intermediate, followed by concert C–C, O–O, C–H bond cleavage and a hydride shift.
Re 2 O 7 catalyzed tandem allylic alcohol isomerization/oxa-Michael addition reaction of cyclohexadienone was developed. The reaction features a regioselective and stereoselective isomerization of ...allylic alcohol and diastereoselective ring closure via oxa-Michael addition. This method also enabled construction of enantiopure bicyclic enones from substrates incorporated with chiral allylic alcohol via efficient chirality transfer.
A phase-field approach to binary alloys is studied. Formal asymptotics of the system of parabolic differential equations leads to new interface relations as part of a macroscopic model which arises ...in the limit of vanishing interface thickness. Under suitable conditions we prove that the phase-field system has a unique solution which converges to the limiting macroscopic solution. The concentration and phase are monotonic across the interface for a simplified system. Transition layers in concentration are induced due to the change in phase and the change in material diffusion across the interface. Excess impurities may be trapped as a consequence of these layers.PUBLICATION ABSTRACT
A highly enantioselective tandem Michael addition of tryptamine‐derived oxindoles to alkynones was developed by taking advantage of a chiral N,N′‐dioxide Sc(OTf)3 catalyst. The reaction enables the ...facile preparation of enantioenriched spiropyrrolidine‐3,3′‐oxindole compounds, which provides a novel strategy for the synthesis of monoterpenoid indole alkaloids. As a demonstration, the asymmetric synthesis of strychnos alkaloids (−)‐tubifoline, (−)‐tubifolidine, (−)‐dehydrotubifoline was achieved in 10–11 steps.
Komplizierter Ringschluss: Bei der Synthese von Strychnos‐Alkaloiden katalysiert ein Komplex aus einem chiralen N,N′‐Dioxid und Sc(OTf)3 die enantioselektive Tandem‐Michael‐Addition von Tryptamin abgeleiteter Oxindole an Alkinone. Die Reaktion liefert enantiomerenangereicherte Spiropyrrolidin‐3,3′‐oxindol‐Verbindungen und demonstriert eine neue Synthesestrategie für Monoterpenoid‐Indolalkaloide.
The total synthesis of FR235222, a potent immunosuppressant with in vivo activities, has been achieved. The key steps include assembling its (2S,9R)-2-amino-9-hydroxy-8-oxodecanoic acid residue via ...an olefin cross-metathesis of a methyl (R)-lactate-derived homoallyl ketone with protected allyl amino acid and constructing its trans-(2R,4S)-4-methylproline unit from protected (R)-pyroglutamic acid in seven steps.
The dienone-phenol rearrangement of 4,4-disubstituted cyclohexadienones catalyzed by Re
2
O
7
has been described. Multi-substituted phenols can be efficiently obtained in good to excellent yields by ...employing this catalytic protocol.
The dienone-phenol rearrangement of 4,4-disubstituted cyclohexadienones to multi-substituted phenols is achieved by employing Re
2
O
7
as the catalyst.
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