Brønsted Acid-Mediated Annulation of α-Oxo Ketene Dithioacetals with Pyrroles: Efficient Synthesis of Structurally Diverse Cyclopenta[<i>b</i>]pyrroles
Brønstedacid‐mediated annulation of internal olefins α‐oxo ketene dithioacetals to pyrroles was efficiently achieved to afford cyclopenta[b]pyrroles. A pair of Brønstedacids with acid strengths, that is, trifluoroacetic acid, and para‐toluenesulfonic acid hydrate, were applied to promote the annulation reactions. The resultant products were readily oxidized to sulfones by meta‐chloroperoxybenzoic
有效地实现了布朗斯台德酸介导的内烯烃α-氧代乙烯酮二硫缩醛与吡咯的环化反应,得到环戊[ b ]吡咯。一对具有酸强度的布朗斯台德酸,即三氟乙酸和对甲苯磺酸水合物,被用于促进环化反应。生成的产物很容易被间氯过氧苯甲酸氧化成砜。随后用1,8-二氮杂双环[5.4.0]十一碳-7-烯处理得到脱硫的烯烃中间体脱硫的末端烯烃或[2 + 2]环加成产物。本协议提供了在温和条件下易于访问结构多样的环戊[ b ]吡咯衍生物的方法。
Regioselective Synthesis of 5-Alkylthio- and 3-Alkylthioisoxazoles from Acylketene Dithioacetals
作者:M. L. Purkayastha、H. Ila、H. Junjappa
DOI:10.1055/s-1989-27133
日期:——
A regioselective synthesis of isomeric 5-alkylthio- and 3-alkylthioisoxazoles 3 and 4 has been developed from acylketene dithioacetals 2. Thus the reaction of 2a-l with hydroxylamine hydrochloride in the presence of sodium methoxide in refluxing methanol afforded 3-substituted 5-alkylthioisoxazoles 3a-l in good yields. When compounds 2a-l were reacted with hydroxylamine hydrochloride in the presence of sodium acetate/acetic acid (pH 2.2) in refluxing ethanol/benzene, 3-alkylthioisoxazoles 4a-l were obtained regioselectively in good yields. Mass-spectral fragmentation and the mechanism of the formation of 3 and 4 are discussed.
A facile oxidative halogenation of α-oxo ketene dithioacetals is achieved by using a potassium halide and oxidant combination under transition metal free conditions at ambient temperature. Using this methodology, halogenatedketene dithioacetals are synthesized in good to excellent yields with a short reaction time. The halogenated products are successfully transformed into nitrogen containing heterocyclic
Solvent free, dry media supported synthesis of a series of 4-aryl/heteroaryl-2-methylthio-3H-1,5-benzodiazepines by chemo- and regioselective cyclization of substituted α-oxoketene dithioacetals with o-phenylenediamines is described. The X-ray crystallographic studies confirmed the formation of the cyclized product.
描述了无溶剂的干燥介质支持的合成的4-芳基/杂芳基-2-甲硫基-3 H -1,5-苯并二氮杂卓的合成,该取代基是通过邻位苯二胺对取代的α-氧杂环丁烯二硫缩醛的化学和区域选择性环化。X射线晶体学研究证实了环化产物的形成。
1,3-Dianionic annulation of ketones with ketene dithioacetal: a modified route to 3-aryl/cyclopropyl-5-thiomethyl-phenols and 1-(methylthio)-9,10-dihydrophenanthren-3-ols
reaction of 2-(bis(methylthio)methylene)-3,4-dihydronaphthalen-1(2H)-ones with different ketones provided 1-(methylthio)-9,10-dihydrophenanthren-3-ols in very good yield. The scope of the reaction was further extended by the synthesis of cyclopropyl-functionalized phenols. One of the compounds was crystallized, and its structure was confirmed using the single-crystal X-ray approach.
开发了一种简单有效的碱介导的 1,3-双阴离子酮与 3,3-双(甲硫基)-1-芳基丙-2-en-1-酮的 [3 + 3] 环化,得到 3-羟基-联芳基、羟基二甲苯和羟基三芳基。由不同的对称和不对称酮制备各种三取代和四取代酚。2-(双(甲硫基)亚甲基)-3,4-二氢萘-1(2H)-酮与不同酮的反应以非常好的产率提供1-(甲硫基)-9,10-二氢菲-3-醇。通过环丙基官能化酚的合成进一步扩展了反应范围。其中一种化合物被结晶,并使用单晶 X 射线方法确认了其结构。