Construction of Spirooxindole Skeleton Through Intramolecular Dieckmann Cyclization

Excited-State Parameters of One Intramolecular Cyclization by TD-DFT, CIS and ZINDO Methods

Using a time-dependent-density functional theory (TD-DFT), Configuration Interaction Singles (CIS) and Zerner’s Intermediate Neglect of Differential Overlap (ZINDO) methods, we have investigated the UV-Visible spectra of one new intramolecular cyclization at before and after intramolecular attack. All structures were optimized at the B3LYP/6-311++G** level while UV-Visible parameters were calcul...

Studies in Dieckmann Cyclization and Utilization of the Products in the Synthesis of Steroids*

Bicyclic sigma receptor ligands by stereoselective Dieckmann analogous cyclization of piperazinebutyrate.

Starting from racemic 2-aminoadipic acid (6) the piperazinedione 10 with a butyrate side chain was synthesized in four reaction steps. The four-carbon bridge was established upon deprotonation of 10 with LHMDS and subsequent trapping of the lithium alcoholate with Me(3)SiCl to give diastereoselectively the mixed methyl silyl ketal 12 in 94% yield. The relative configuration of the new center of...

Fast Skeleton Construction

For a polygon P , the skeleton of P is a partition of P into regions assigned to the edges of P: A point p inside P belongs to the region of an edge e if and only if e is the closest edge of P: We present a randomized algorithm that builds the skeleton of a simple polygon in linear expected time. We also observe that the Delaunay triangulation (equivalently, the Voronoi diagram) of a planar poi...

Intramolecular cyclization of propargyl derivatives using environmentally friendly methodologies*

The electrochemical intramolecular cyclization of propargyl derivatives containing a carbon–halogen bond in N,N’-dimethylformamide at constant current in a diaphragmless cell has been developed using Ni(II) complexes as electron-transfer mediators.