Phenyl tetrazolyl sulfones

The best version of the Julia olefin synthesis (so far) is probably that introduced by Kocienski.33 It uses /V-phenyl tetrazolyl sulfones 167 easily prepared from the available thiol 165 by a Mitsunobu reaction with a simple alcohol followed by oxidation. 

Herboxidiene 154 shows potent herbicidal activity and up-regulates gene expression of low density lipoprotein receptors. Kocienski and coworkers synthesized herboxidiene 154 successfully from two key fragments using a modified Julia olefmation based on the benzothiazolyl sulfone activator. The yield was 81% with excellent selectivity 0E Z = 91 9) by one-port reaction between sulfone 152 and the aldehyde 151. 1-Phenyl-1/f-tetrazolyl sulfone 149 was used as activator in the synthesis of the C -Cio oxane fragment 151. Addition of KHMDS to the mixture of sulfone 149 and aldehyde 148 in 1,2-dimethoxyethane at -60 °C gave a 93% yield of the alkene 151 with good stereoselectivity (E Z = 93 1). 

The sulfones prepared can be metallated with KHMDS at low temperature and, unlike the related benzothiazolyl and 1-phenyl-li/-tetrazolyl systems, show excellent stability with little tendency to self-condense. Selectivities observed in olefinations are good to excellent in favor of the Z-isomers (eq 3). 

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