title: Ring openings of lactone and ring contractions of lactide by frustrated Lewis pairs.
abstract: While B(C(6)F(5))(3) forms the adducts (CH(2))(4)CO(2)B(C(6)F(5))(3)1 and (CHMeCO(2))(2)B(C(6)F(5))(3)7 with δ-valerolactone and lactide, the frustrated Lewis pairs derived from B(C(6)F(5))(3) and phosphine or N-bases react with lactone to effect ring opening affording zwitterionic species of the form L(CH(2))(4)CO(2)B(C(6)F(5))(3) (L = tBu(3)P 2, Cy(3)P 3, C(5)H(3)Me(3)N 4, PhNMe(2) 5, C(5)H(6)Me(4)NH 6) while reaction with rac-lactide results in ring contraction to give salts [LH][OCCHMeCO(2)(CMe)OB(C(6)F(5))(3)] (L = tBu(3)P 8, Cy(3)P 9, C(5)H(3)Me(2)N 10, C(5)H(6)Me(4)NH 11). The mechanistic implications of these reactions are discussed.
authors: Department of Chemistry, 80 St. George St., University of Toronto, Toronto, Ontario, Canada M5S 3H6.
authors: Christoph
authors: C
authors: Kreitner
authors: Stephen J
authors: SJ
authors: Geier
authors: Louisa J E
authors: LJ
authors: Stanlake
authors: Christopher B
authors: CB
authors: Caputo
authors: Douglas W
authors: DW
authors: Stephan