The reaction of metallated 1-phenyl-1H-tetrazol-5-yl sulfones and aldehydes gives good yields and stereoselectivity of trans-1,2-disubstituted alkenes when potassium or sodium hexamethyldisilazide is used as base and 1,2-dimethoxyethane is used as solvent.In 1991 Sylvestre Julia and co-workers 1 reported a new connective onepot synthesis of alkenes involving the reaction of lithiated 2-benzothiazolyl sulfones with carbonyl compounds (Scheme 1). The reaction involves addition of carbanion 1 to the carbonyl compound to give adduct 2 which then undergoes a series of transformations resulting in the expulsion of sulfur dioxide and the lithium derivative of 1,3-benzothiazol-2-one (5) with concomitant formation of the alkene. A detailed study of 100 examples revealed some important limitations to the method 2,3 : (1) high stereoselectivities are only obtained in special cases; e.g. the formation of some conjugated dienes; and (2) some lithiated benzothiazolyl sulfones are unstable and undergo selfcondensation even at low temperature. This side reaction necessitated the use of "Barbier-type" reaction conditions, i.e., the addition of the base to a mixture of sulfone and aldehyde in which case the sulfone lithiates in situ and addition of the lithiated sulfone to the aldehyde takes place faster than self-condensation. Unfortunately, such reaction conditions are likely to be incompatible with complex aldehyde substrates. Scheme 1Application of the Julia olefination (Note 1) to the synthesis of the conjugated diene segment of Herboxidiene A 4 and the conjugated triene segment of Rapamycin 5 showed that high efficiency and good stereoselectivity could be secured by varying the base and the solvent with best results being obtained using sodium hexamethyldisilazide as base in a non-polar solvent (Note 2). Unfortunately early attempts to extend these findings to a synthesis of simple alkenes gave poor stereoselectivity (vide infra). Further improvements in carbanion stability and stereoselectivity were sought by varying the heterocycle. Julia had already shown that 2-pyridyl and 2-pyrimidyl sulfones participate in the reaction though no particular advantages were noted 3 . We re-examined Julia's results and extended the range of heterocycles to 1-isoquinolinolyl, 1-methyl-2-imidazolyl, 4-methyl-1,2,4-triazol-3-yl, and 1-phenyl-1H-tetrazol-5-yl. Our preliminary results indicated that the 1-phenyl-1H-tetrazol-5-yl system showed sufficient promise to warrant an extended study which is the subject of this communication (Note 3).In order to assess the influence of chain branching, base and solvent on the stereoselectivity of the reaction, four alkenes were synthesised as depicted in Tables 1-4. In each case the performance of the 1-phenyl-1H-tetrazol-5-yl (PT) sulfones 7 and 11 (Note 4) was assessed in relation to their well established benzothiazol-2-yl (BT) sulfone counterparts 6 and 10. All 96 experiments were conducted as follows.To a stirred solution of the sulfone (0.2 mmol) and dodecane (23 µl, 0.1 mmol, internal standard) i...

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