Selenium reactions

This sulfur work was preceded by a conceptually related selenium reaction (Scheme 43).In accord with this mechanism, 1-vinylcycldiexene gives predominantly the isomer substituted at the more hindered endocyclic double boid. 

A number of useful enantioselective syntheses can be performed by attaching a chiral auxihary group to the selenium atom of an appropriate reagent. Examples of such chiral auxiliaries include (49-53). Most of the asymmetric selenium reactions reported to date have involved inter- or intramolecular electrophilic additions to alkenes (i.e. enantioselective variations of processes such as shown in equations (23) and (15), respectively) but others include the desymmefrization of epoxides by ringopening with chiral selenolates, asymmetric selenoxide eliminations to afford chiral allenes or cyclohexenes, and the enantioselective formation of allylic alcohols by [2,3]sigmafropic rearrangement of allylic selenoxides or related species. 

Some sulfonium ylid chemistry, revision on rearrangements (Chapter 37), and some simple selenium reactions. 

C. J. Sandorff et al.. Enhanced Electronic Properties of GaAs Surfaces Chemically Passivated by Selenium Reactions, J. Appl. Phys. 1990, 67(1), 586-588. 

CuSOz 3 H2O, reagent purity, 10 % in dist. water Potassium sulphate, K2SO, reagent purity Wieninger s selenium reaction mixture... 

C-labeled carbamoyl compounds can be prepared by using a selenium-mediated reaction with [ carbon monoxide. The urea formation works excellent in the case of cyclizations but in other cases satisfactorily only with primary amines (Kihlberg et al. 2002). Since selenium is practically insoluble in most solvents the use of primary alkyl amines or tetrabutylammonium fluoride is necessary for the formation of soluble and reactive complexes with selenium. Except for ring closures, rhodium-promoted carbonylations are probably more useful than the corresponding selenium reactions (Ohad et al. 2009). 

Selenium Reaction with diaminobenzidine, forming colored species absorbing at 420 mn... 

Photometric and fluormetric analysis is based on the measurement of the following products of selenium reactions ... 

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