α-allylated chiral thioxanones: Diastereoselective preparation by an S-alkylation/[2,3]-sigmatropic rearrangement sequence.
摘要:
Diastereoselective S-allylation of thioxanone 6 and subsequent ylid formation/[2,3]-sigmatropic rearrangement delivers excellent C-alpha-induction. Non-stereospecific C-beta-induction results from scrambling of olefin geometry in the S-allylation step.
A thioxanone-based chiral template: asymmetric induction in the [2,3]-sigmatropic rearrangement of sulfur ylides. Enantioselective preparation of C.beta.-chiral pent-4-enoic acids
The present invention relates to peptide conjugates of cytotoxins such as topoisomerase I inhibitors which are useful for the treatment of diseases such as cancer.
conformation and face selectivity was to be controlled through non-bonded steric interactions. Chirality was introduced from chiral pool materials (camphor, amino acids, lactic acid, limonene, carvone, glyceraldehyde), through enzyme mediated reduction/hydrolysis and through the use of chiral reagents (hydroboration). The sulfide catalysts were tested in the reaction between benzaldehyde tosylhydrazone salt
Highly diastereoselective formation of bicyclic compounds by intramolecular cycloaddition of chiral thiaalkenyl nitrones
作者:Hans Günter Aurich、Jose-Luis Ruiz Quintero
DOI:10.1016/s0040-4020(01)89668-x
日期:1994.3
Starting from chiral mercapto alcohols 5 in several reaction steps nitrones 7 were formed which underwent spontaneously intramolecular cycloaddition to give diastereomerically pure products 8. However, during the reaction course partial racemization had occurred. In contrast, nitrones 9 in which the chiral center is adjacent to the nitrogen atom afforded a mixture of the two diastereomeric cycloadducts