1,3-Dipolar Cycloadditions to (5Z)-1-Acyl-5-(cyanomethylidene)- imidazolidine-2,4-diones: Synthesis and Transformations of Spirohydantoin Derivatives
作者:Uroš Grošelj、Aleš Drobnič、Simon Rečnik、Jurij Svete、Branko Stanovnik、Amalija Golobič、Nina Lah、Ivan Leban、Anton Meden、Simona Golič-Grdadolnik
DOI:10.1002/1522-2675(20011114)84:11<3403::aid-hlca3403>3.0.co;2-g
日期:2001.11.14
neutral conditions, spirohydantoin derivatives 12 – 16 were obtained (Scheme 2), while under basic or acidic conditions, pyrazole- or isoxazole-5-carboxamides 18 and 23 – 26 and carboxylate 27 were formed via aromatization of the newly formed dihydroazole ring, followed by the simultaneous cleavage of the hydantoin ring (Schemes 3 – 5).
各种 1,3-偶极子与 (5Z)-1-acyl-5-(cyanomethylidene)-3-methylimidazolidine-2,4-diones 8 或 9 的环加成反应,由乙内酰脲 (1) 分 3 步制备(方案 1 和 2 ),进行了研究。在所有情况下,反应都以区域选择性和立体选择性进行。产物的类型取决于所用的 1,3-偶极子和/或亲偶极子以及反应条件。因此,在中性条件下具有稳定的偶极子,得到螺乙内酰脲衍生物 12-16(方案 2),而在碱性或酸性条件下,吡唑-或异恶唑-5-甲酰胺 18 和 23-26 以及羧酸盐 27 通过芳构化形成新形成的二氢唑环,随后乙内酰脲环同时裂解(方案 3-5)。