Nitrosonium salts, NO+ X- (X = B(3,5-diCF3Ph)4(-) or PW12O40(3-)), as electrophilic catalysts for alkene activation in arene alkylation and dimerization reactions.
It has been found that in apolar reaction media the nitrosonium cation (NO+) activated alkenes under mild conditions toward electrophilic substitution of arene substrates to yield the alkylated arene with Markovnikov orientation. In the absence of arenes the alkenes react with themselves to yield a mixture of dimeric alkenes. The nitrosonium cation can be dissolved in the reaction medium by using the tetrakis-(bis-(3,5-trifluromethyl)phenyl) borate anion, where upon the reactions occur effectively at 30 degrees C. Alternatively an insoluble, heterogeneous catalyst was prepared so as to yield a NO+ cation with a polyoxometalate (PW12O403-) anion. This catalyst was generally more effective and selective toward a broader range of substrates at 70 degrees C.
Khenkin
Alexander M
AM
Department of Organic Chemistry, Weizmann Institute of Science, Rehovot, Israel 76100.
Neumann
Ronny
R