Notizen: Montmorillonite K-10 as Highly Efficient and Mild Catalyst for Deprotection of Ketone Dimethylhydrazones Using Microwaves in a Solventless System
Working three shifts: Polyconjugated δ‐diketones are formed stereoselectively in high yields by the gold‐catalyzed rearrangement of 1,6‐diyn‐3‐yl esters. This cascade involves a 1,3‐sigmatropic acyloxy shift, a 5‐exo‐dig cyclization of the resulting allenyne, and an unprecedented 1,5‐sigmatropic shift of an acyl fragment. The usefulness of the products was shown by an efficient acid‐catalyzed transformation
The 2-(2-Azidoethyl)cycloalkanone Strategy for Bridged Amides and Medium-Sized Cyclic Amine Derivatives in the Aubé-Schmidt Reaction
作者:John Murphy、Fraser Macleod、Stuart Lang
DOI:10.1055/s-0029-1219340
日期:2010.3
2-(2-Azidoethyl)cycloalkanones afford bridged lactams in the Aube-Schmidt reaction, sometimes in excellent yield, and solvolysis yields derivatives of medium-ring amines. Attempts to divert the Schmidt reaction with an arene-mediated fragmentation of the normal Schmidt intermediate have led to an initial example.
Catalytic α‐arylation of ketones in an umpolung fashion was demonstrated through nucleophilic addition of phenol derivatives to the electrophilic oxy‐allyl cation intermediates, allowing the formation of ketones bearing an all carbon quaternary center at the α‐position.
Intramolecular reductive coupling of cycloalkanones tethered to alkynoates in the presence of (η2-propene)titanium was successfully performed to provide hydroxy-esters in a diastereoselective manner. Subsequent lactonization afforded angularly fused unsaturated tricyclic lactones which represent relevant substructures of numerous bioactive compounds.
Stereoselective synthesis of carbocyclic ring systems by pinacol-terminated Prins cyclizations
作者:Timothy C Gahman、Larry E Overman
DOI:10.1016/s0040-4020(02)00658-0
日期:2002.8
Studies that expand the scope of the Prins-pinacol synthesis of carbocyclicring systems are described. The construction of cyclopentacyclooctanones by ring-enlarging cyclopentane annulations of cycloheptanone precursors is broadly examined as is the synthesis of related bicyclic ketones containing larger rings. Prins-pinacol reactions of acyclic alkenyl acetals were examined to gain insight into intrinsic