Lithiated γ- O-functionalized propyl phenyl sulfides and sulfones of the type Li[CH(SO xPh)CH 2CH 2OR] ( x = 0, 2). [Li{CH(SPh)CH 2CH 2O t-Bu}(tmeda)] – A structurally characterized organolithium inner complex

Abstract

Lithiation of O-functionalized alkyl phenyl sulfides PhSCH 2CH 2CH 2OR (R = Me, 1a; i-Pr, 1b; t-Bu, 1c; CPh 3, 1d) with n-BuLi/tmeda in n-pentane resulted in the formation of α- and ortho-lithiated compounds [Li{CH(SPh)CH 2CH 2OR}(tmeda)] (α- 2a– d) and [Li{ o-C 6H 4SCH 2CH 2CH 2OR)(tmeda)] ( o- 2a– d), respectively, which has been proved by subsequent reaction with n-Bu 3SnCl yielding the requisite stannylated γ-OR-functionalized propyl phenyl sulfides n-Bu 3SnCH(SPh)CH 2CH 2OR (α- 3a– d) and n-Bu 3Sn( o-C 6H 4SCH 2CH 2CH 2OR) ( o- 3a– d). The α/ ortho ratios were found to be dependent on the sterical demand of the substituent R. Stannylated alkyl phenyl sulfides α- 3a– c were found to react with n-BuLi/tmeda and n-BuLi yielding the pure α-lithiated compounds α- 2a– c and [Li{CH(SPh)CH 2CH 2OR}] (α- 4a– b), respectively, as white to yellowish powders. Single-crystal X-ray diffraction analysis of [Li{CH(SPh)CH 2CH 2O t-Bu}(tmeda)] (α- 2c) exhibited a distorted tetrahedral coordination of lithium having a chelating tmeda ligand and a C, O coordinated organyl ligand. Thus, α- 2c is a typical organolithium inner complex. Lithiation of O-functionalized alkyl phenyl sulfones PhSO 2CH 2CH 2CH 2OR (R = Me, 5a; i-Pr, 5b; CPh 3, 5c) with n-BuLi resulted in the exclusive formation of the α-lithiated products Li[CH(SO 2Ph)CH 2CH 2OR] ( 6a– c) that were found to react with n-Bu 3SnCl yielding the requisite α-stannylated compounds n-Bu 3SnCH(SO 2Ph)CH 2CH 2OR ( 7a– c). The identities of all lithium and tin compounds have been unambiguously proved by NMR spectroscopy ( 1H, 13C, 119Sn).