Metalation and Electrophilic Quenching of C-4 Functionalized Isoxazoles; VIII. Preparation of Derivatives of 5-Thioalkylisoxazoles
作者:T. N. Balasubramaniam、Yousef R. Mirzaei、N. R. Natale
DOI:10.1055/s-1990-27099
日期:——
The lateral metalation and electrophilic quenching of isoxazoles bearing electron withdrawing groups in the 4-position 1 with disulfides, represents a selective, direct and synthetically useful entry to the thioalkyl derivatives 2 (nine examples). One exception to the formation of monothioalkyl major products was observed for the dianion of 4-[(2-hydroxymethyl-1-pyrrolidinyl)carbonyl]-3,5-dimethylisoxazole (1i) which was found to produce the 5-[bis(phenylthio)methyl]isoxazole derivative 3i as the major isolated product (66%). Oxidation of 2a with 3-chloroperoxybenzoic acid (MCPBA) proceeds selectively at sulfur in the presence of both isoxazole and oxazoline nitrogens to give the corresponding sulfoxide 4a (56%) or sulfone 5a (72%), respectively.
在 4-位 1 上带有吸电子基团的异恶唑与二硫化物的横向金属化和亲电子猝灭代表了硫代烷基衍生物 2 的选择性、直接和合成上有用的进入(九个例子)。 对于 4-[(2-羟甲基-1-吡咯烷基)羰基]-3,5-二甲基异恶唑 (1i) 的二阴离子,观察到形成单硫代烷基主要产物的一个例外,发现它会产生 5-[双(苯硫基) )甲基]异恶唑衍生物 3i 作为主要分离产物 (66%)。在异恶唑和恶唑啉氮存在下,用 3-氯过苯甲酸 (MCPBA) 选择性地对硫进行氧化,分别得到相应的亚砜 4a (56%) 或砜 5a (72%)。