REACTIONS OF T-BUOK AND DIBENZYL, BENZYL ALLYL, AND ALLYL BETA-KETO SULFIDE COMPLEXES OF THE CHIRAL RHENIUM LEWIS-ACID [(ETA(5)-C5H5)RE(NO)(PPH(3))](- HIGHLY DIASTEREOSELECTIVE OR CHEMOSELECTIVE [2,3]-SIGMATROPIC REARRANGEMENTS() )

Reaction of the dibenzyl sulfide complex (eta(5)-C5H5)Re(NO(PPh(3)(S(C H(2)Ph)(2))](+)TfO(-) (4a(+)TfO(-)) and t-BuOK (THF, -80 degrees C) gi ves the thiolate (eta(5)-C5H5)Re(NO)(PPh(3))(SCH(o-C6H4CH3)Ph) (5a; 99 %) as a 96:4 mixture of SR,RS/SS,RR Re:C diastereomers. This transform ation involves initial deprotonation of a benzyl group to give an ylid e, followed by [2,3]- and [1,3]- rearrangements. A crystal structure o f (SR,RS)-5a establishes the configuration. Similar reactions of the b enzyl allyl sulfide complexes 5H5)Re(NO)(PPh(3))(S(CH(2)CR=CH2)CH2-Ph) ](+)TfO(-) (R = H, CH3) give mainly the thiolates RR)-(eta(5)-C5H5)Re( NO)(PPh(3)(SCH(CH2-CR=CH2)Ph), derived from benzyl group deprotonation . Some thiolates derived from allyl group deprotonation also form. Sim ilar reactions of the allyl beta-keto sulfide complexes [(eta(5)-C(5)R (5))Re(No)(PPh(3))(S(CH(2)CR'=CR ''(2))CH(2)COPh)](+)X(-) (R/R'/R '' = H/H/H, H/H/CH3, H/CH3/H, CH3/H/H) give the thiolates -C(5)R(5))Re(NO) (PPh(3))(SCH(CR''(2)CR'=CH2)COPh), derived from CH(2)COPh group deprot onation, as >96: <4 to 68:32 diastereomer mixtures. Reactions of 4a ()TfO(-) with MeLi give mainly the [1,2]-rearrangement product (eta(5)- C5H5)Re(NO)(PPh(3))-(SCH(CH(2)Ph)Ph) ((35-70):(65-30) diastereomer mix tures), which has been independently synthesized. The thiolate ligands are easily converted to free methyl sulfides. Mechanisms of diastereo selection, and similar reactions of organic sulfonium salts, are discu ssed.