Reactivity of 13,13-Dibromo-2,4,9,11-tetraoxadispiro[5.0.5.1]tridecane toward Organolithiums: Remarkable Resistance to the DMS Rearrangement
作者:Wendy Eccles、Marcin Jasinski、Piotr Kaszynski、Katarzyna Zienkiewicz、Baldur Stulgies、Aleksandra Jankowiak
DOI:10.1021/jo800054p
日期:2008.8.1
cyclohexane analogue 2b treated with MeLi underwent a smooth rearrangement to bicyclo[1.1.0]butane 11b at −78, −10, or +35 °C. Treatment of 2a with PhLi gave the α-Ph anion 13 as the only product, which underwent smooth methylation with MeI to give 14. Under the same conditions, 2b with PhLi gave bicyclo[1.1.0]butane 11b accompanied by bromophenyl derivative 8b. Treatment of either dibromide with t-BuLi gave
含有两个螺稠合的1,3-二恶烷环的二溴环丙烷2a与MeLi的反应即使在高温下也仅给出了甲基化产物8和9。相反,用MeLi处理的环己烷类似物2b在-78,-10或+ 35℃下平滑重排成双环[1.1.0]丁烷11b。用PhLi处理2a得到的唯一产物是α-Ph阴离子13,然后用MeI进行平滑甲基化得到14。在相同条件下,2b与PhLi一起生成双环[1.1.0]丁烷11b,并伴有溴苯基衍生物8b。用t- BuLi处理任何一种二溴化物都会得到包括脱溴环丙烷12在内的多种产物的混合物。盐23的DFT计算和卡宾22的MP2 // DFT级计算增加了实验结果。他们证明,相对于α-消除,二恶烷α-溴阴离子的稳定性更高,为4.8 kcal / mol,与环己烷类似物相比,卡宾22a发生4.0 kcal / mol的重排的可能性更低。这些差异归因于四个氧原子的感应效应,这导致较低的LUMO能量,在羧基中心的较高