A<sup>1</sup>H and<sup>13</sup>C NMR Study of the Structure of Sulfur-Stabilized Lithiated Allylic Carbanions
作者:Lionel Glendenning、Leslie D. Field、Richard K. Haynes
DOI:10.1246/bcsj.68.2739
日期:1995.9
NMR studies of the solution structures of lithiated (E)-1-(t-butylthio)but-2-ene (4) and lithiated (E)-1-(phenylthio)but-2-ene (6) are reported. The structure of lithiated (E)-1-(t-butylthio)but-2-ene (4) is best described as a transoid carbanion with the allylic carbons C1, C2, and C3 having intermediate sp2–sp3 hybridization. In (4) the heteroatom and non-allylic substituent do not play any significant role in carbanion stabilization. Lithiated (E)-1-(phenylthio)but-2-ene (6) differs from (4) in that it exhibits cis geometry about the C1–C2 bond and the phenylthio group participates in helping to stabilize allylic charge. There is a discrepancy between the geometry about the C1–C2 bond in the solution and solid structures of (4) in the presence of TMEDA.
报告了对石炭酸化 (E)-1-(t-butylthio)but-2-ene (4) 和石炭酸化 (E)-1-(phenylthio)but-2-ene (6) 溶液结构的核磁共振研究。石碳酸化 (E)-1-(t-丁硫基)丁-2-烯 (4) 的结构最适合描述为烯丙基碳 C1、C2 和 C3 具有中间 sp2-sp3 杂化的横烷碳阴离子。在(4)中,杂原子和非烯丙基取代基在碳阴离子的稳定方面不起任何重要作用。锂化 (E)-1-(phenylthio)but-2-ene (6) 与 (4) 的不同之处在于,它在 C1-C2 键上呈现顺式几何结构,苯硫基参与帮助稳定烯丙基电荷。在 TMEDA 的存在下,(4) 的溶液和固体结构中 C1-C2 键的几何形状存在差异。