Synthesis of 2<i>H</i>-1,2-Benzothiazine 1,1-Dioxides via Heteroannulation Reactions of 2-Iodobenzenesulfonamide with Ketone Enolates under S<sub>RN</sub>1 Conditions
作者:William J. Layman,、Thomas D. Greenwood、Aaron L. Downey、James F. Wolfe
DOI:10.1021/jo050964e
日期:2005.11.1
reaction to the preparation of 2H-1,2-benzothiazin-3(4H)-one 1,1-dioxides 3 (R = H, Ph) through reactions of 1a with tert-butyl acetate and ethyl phenylacetate enolates resulted only in hydrodehalogenation of 1a. However, oxazoline anion 30, a synthetic equivalent of ethyl phenylacetate, was successfully employed in an alternative SRN1-based synthesis of benzothiazine 3 (R = Ph).
2-碘苯磺酰胺(1a)在液态NH 3中与衍生自丙酮,频哪酮,丁酮和3-甲基-2-丁酮的烯醇钾进行光刺激的S RN 1反应,以公平地获得良好的2 H -1,2-收率。苯并噻嗪1,1-二氧化物2。发现1a的还原脱卤作用在1a与3-戊酮,2-甲基-3-戊酮和2,4-二甲基-3-戊酮的光诱导反应中占主导地位,还原程度与β-氢原子数量成正比。酮烯醇中存在的原子。2,4-二甲基-3-戊酮-d 14(24的同位素标记研究)证实了β-氢在还原过程中的主要作用。的反应1A与环戊酮,环己酮,并得到新的三环苯并噻嗪衍生物环辛烯醇化物26 - 29。尝试通过1a与乙酸叔丁酯和乙酸乙酯的反应将杂环化反应扩展到制备2 H -1,2-苯并噻嗪-3(4 H)-1 1,1-二氧化物3(R = H,Ph)苯乙酸烯醇盐仅导致1a的加氢脱卤。但是,恶唑啉阴离子30(苯乙酸乙酯的合成当量)已成功用于替代S基于RN 1的苯并噻嗪3的合成(R