an efficient one-pot three-component procedure for the synthesis of new chiral spiro-oxindolopyrrolizidines with highly regio-, diastereo-, and enantioselective from 1,3-dipolar cycloaddition of azomethine ylides and optically pure active cinamoyl oxazolidinone are described. the process occurs at room temperature in aqueous ethanol as green solvent and in the absence of any bidentate chelating...

Biodegradable polyesters such as poly(ϵ-caprolactone) (PCL) and poly(lactic acid) (PLA) have been considered for use in several areas, drug delivery devices, sutures, tissue engineering, GBR membranes, due to its bio-renewability, biodegradability, biocompatibility. Several synthetic techniques the preparation of reported literature, amongst which ring-opening polymerization (ROP) cyclic esters...

Highly diastereoselective asymmetric synthesis of chiral aziridine-2-carboxylic esters is reported for 20 examples with good yields (51-87%) and excellent diastereoselectivities (>99:1 dr for most cases). The modified N-phosphonyl imines have proven to be superior to previous imine auxiliaries for the aza Darzens reaction by using a secondary isopropyl group to replace the primary benzyl group ...

Density functional theory calculations and experiment reveal the origin of stereoselectivity in the deprotonation-alkylation of chiral N-amino cyclic carbamate (ACC) hydrazones. When the ACC is a rigid, camphor-derived carbamate, the two conformations of the azaenolate intermediate differ in energy due to conformational effects within the oxazolidinone ring and steric interactions between the A...

A bidirectional ortho metalation of the readily available chiral diol hydrobenzoin has been developed that provides direct access to new ortho-functionalized hydrobenzoin derivatives. This one-pot procedure should broaden the utility of hydrobenzoin as an auxiliary and ligand in asymmetric synthesis.

An efficient, enantioselective synthesis of apoptolidinone has been completed, demonstrating the versatility of thiazolidinethione auxiliaries. Three propionate aldol additions and two asymmetric glycolate alkylations function to establish 8 of the 12 stereogenic carbon centers. A cross-metathesis reaction is utilized to assemble the C1-C10 trieneoate fragment and the C11-C28 polypropionate reg...

in recent years there has been considerable interest in the synthesis and separation of enantiomers of organic compounds especially because of their importance in the biochemistry and pharmaceutical industry. high-performance liquid chromatography is a very useful method for the direct separation of enantiomers. however, about 30−40 years ago, commercially available chiral stationary phases wer...

This paper focuses on two disparate aspects of German syntax from the perspective of parallel grammar development. As part of a cooperative project, we present an innovative approach to auxiliaries and multiple genitive NPs in German. The LFG-based implementation presented here avoids unnessary structural complexity in the representation of auxiliaries by challenging the traditional analysis of...

1.1 Dyeing auxiliaries Auxiliaries are compounds which are not an integral part of the dyeing process but by adding them to the dye bath the dyeing can be improved. The main functions of auxiliaries are to prepare or improve the substrate in readiness for colorants (by wetting, providing sorption sites, improving or resisting the migration of dyes), to stabilize the application media (by improv...