Trapping of trifluoroacetonitrile imines with mercaptoacetaldehyde and mercaptocarboxylic acids: An access to fluorinated 1,3,4-thiadiazine derivatives via (3+3)-annulation
作者:Greta Utecht-Jarzyńska、Aleksandra Michalak、Justyna Banaś、Grzegorz Mlostoń、Marcin Jasiński
DOI:10.1016/j.jfluchem.2019.04.012
日期:2019.6
The in situ generated highly electrophilic nitrile imines derived from trifluoroacetonitrile are efficiently trapped by monomeric mercaptoacetaldehyde at room temperature in THF solution. The initially formed 1:1 adducts undergo spontaneous cyclization leading to 6-membered 5,6-dihydro-1,3,4-thiadiazin-5-ols bearing the CF3 group at the C(2) atom in good yields. Subsequent oxidation of the latter products
在原位从trifluoroacetonitrile衍生产生高度亲电腈亚胺有效地单体mercaptoacetaldehyde在THF溶液室温下捕获。最初形成的1:1加合物经历自发环化反应,从而以高收率得到在C(2)原子上带有CF 3基团的6元5,6-二氢-1,3,4-噻二嗪-5-醇。随后的产物用C 5 H 5 N∙HCl·CrO 3氧化(PCC)平稳地生产了预期的1,3,4-噻二嗪-5-酮类产品。另外,类似的2-三氟甲基化的杂环化合物是通过用α-巯基羧酸然后用1- [3-(二甲基氨基)丙基] -3-乙基碳二亚胺甲硫醚(EDC甲硫醚)诱导的最初形成的1的环化作用捕获相同的腈亚胺而获得的: 1个加合物。通常,第二种方法的效率较低,并且取决于起始1,3-偶极子中与苯环相连的取代基的类型。