Notizen: Montmorillonite K-10 as Highly Efficient and Mild Catalyst for Deprotection of Ketone Dimethylhydrazones Using Microwaves in a Solventless System
N,N-Dimethylhydrazones of ketones were efficiently and rapidly deprotected to the corresponding ketones by Montmorillonite K-10 clay using microwave irradiation under solvent free conditions.
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
Diastereoselective Addition of Zincated Hydrazones to Alkenylboronates and Stereospecific Trapping of Boron/Zinc Bimetallic Intermediates by Carbon Electrophiles
pinacol esters to produce alpha-alkylated-gamma-boryl-gamma-zinciohydrazone intermediates with good to excellent diastereoselectivity (ds). The 1,1-organodimetallic intermediate possessing a boron atom and a zinc atom in the position gamma to the hydrazone group undergoes further C-C bond formation with a carbon electrophile to give a gamma-boryl hydrazone possessing several contiguousstereogenic centers
Iron/copper promoted fragmentation reactions of α-alkoxy hydroperoxides
作者:Stuart L Schreiber、Bernard Hulin、Wai-fong Liew
DOI:10.1016/s0040-4020(01)90584-8
日期:1986.1
Several new examples of iron/copper mediated fragmentationreactions of hydroperoxides are reported. The regio- and stereochemistry of olefin formation is in accord with a model that takes into account the preferred conformations of the radical intermediate and potential olefin products. In combination with group selective peroxyketalization reactions, several stereocontrolled syntheses of olefin containing
Synthetic methodology for the preparation of trans- and cis-2,9-disubstituted oxonanes
作者:Robert W. Carling、Neil R. Curtis、Andrew B. Holmes
DOI:10.1016/s0040-4039(01)93860-2
日期:1989.1
Methylenation of the racemic lactone (5), followed by stereoselective hydroboration, gave predominantly the trans-2,9-disubstituted oxonane (7) which was converted into the carbon skeleton (1) of obtusenyne (2). Epimerisation of the trans-aldehyde (18) gave the cis-compound (19). Relative stereochemistry was established by the asymmetric synthesis of trans-(2R),(9R)-dimethyloxonane (13) and meso cis-2,9-dimethyloxonane