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 Academic Article uri icon


  • Reaction of the dibenzyl sulfide complex [(5-C5H5)Re(NO)(PPh3(S(CH 2Ph)2)]+TfO- (4a+TfQ-) and t-BuOK (THF, -80C) gives the thiolate (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 transformation involves initial deprotonation of a benzyl group to give an ylide, followed by [2,3]- and [1,3]-rearrangements. A crystal structure of (SR,RS)-5a establishes the configuration. Similar reactions of the benzyl allyl sulfide complexes [(5-C5H5)Re(NO)(PPh3)(S(CH 2CR=CH2)CH2-Ph)]+TfO- (R = H, CH3) give mainly the thiolates (SS,RR)-(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. Similar reactions of the allyl -keto sulfide complexes [(5-C5R5)Re(NO)(PPh3)(S(CH 2CR=CR2)CH2COPh)]+X- (R/R/R = H/H/H, H/H/CH3, H/CH3/ H, CH3/H/H) give the thiolates (5-C5R5)Re(NO)(PPh 3)(SCH(CR2CR=CH2)COPh), derived from CH2COPh group deprotonation, as >96: <4 to 68:32 diastereomer mixtures. Reactions of 4a+TfO- with MeLi give mainly the [1,2]-rearrangement product (5-C5H5)Re(NO)(PPh 3)-(SCH(CH2Ph)Ph) ((35-70):(65-30) diastereomer mixtures), which has been independently synthesized. The thiolate ligands are easily converted to free methyl sulfides. Mechanisms of diastereoselection, and similar reactions of organic sulfonium salts, are discussed.

published proceedings


author list (cited authors)

  • Cagle, P. C., Meyer, O., Vichard, D., Weickhardt, K., Arif, A. M., & Gladysz, J. A.

citation count

  • 18

complete list of authors

  • Cagle, PC||Meyer, O||Vichard, D||Weickhardt, K||Arif, AM||Gladysz, JA

publication date

  • January 1996