Regioselective synthesis of spiro isoxazole‐oxindole‐tetrahydrothiophene hybrids via cascade reactions under catalyst‐free conditions

Abstract

Catalyst-free synthesis of the isoxazole-spirooxindole-tetrahydrothiophene hybrids is reported. Formation of 1,4-thia-Michael and intramolecular aldol reactions were observed (instead of 1,6-thia-Michael followed by vinylogous Henry reactions) in a regioselective fashion to give new isoxazolespirooxindole-tetrahydrothiophene hybrids with excellent yields.

Supported l-tryptophan on Fe3O4@SiO2 as an efficient and magnetically separable catalyst for one-pot construction of spiro[indene-2,2′-naphthalene]-4′-carbonitrile derivatives

“…13,14 Furthermore, vinylogous Michael addition was reported as a key step in the preparation of many spiro compounds. [15][16][17] In recent years, a few synthesis methods for the synthesis of spiro[indene-2,2 0 -naphthalene]-4 0 -carbonitriles have been reported in the literature. L-Proline, 18 ethylene glycol 19 and quaternary ammonium surfactant [C 18 -Dabco][Br] 20 have been utilized in these methods.…”

Research Progress on Reactions Involving β-Nitrostyrene

“…该实验证明简单的双 官能胺硫脲比 Brønsted 碱/Lewis 酸体系能更有效地控制 非对映选择性. 2019 年, Kashinath 课题组 [104] 发现 1,4-二 噻烷-2,5-二醇和 β-硝基苯乙烯在无催化剂且乙醇作溶 剂条件下, 也可以合成噻吩, 且产率最高可达 95%.…”

Advances in the Synthesis of Benzo‐Fused Spiro Nitrogen Heterocycles: New Approaches and Modification of Old Strategies

“…When heated, compounds 144 and dithiane diol 145 in ethanol gave the expected spirocyclic products 146 in a short time in good yield (Scheme 38). [202] Earlier, a catalytic variant of the synthesis of enantiomers of compound 147 was carried out using chiral squaramides 117b or 117c (squaramides see Figure 1). In these syntheses, when squaramide 117b was used as the organocatalyst, high diastereoselectivity dr � 11 : 1 was observed in the case of cycloaddition of N-methyl-3-ylideneoxindoles 148 (X=H, 5-Me, 5-OMe, 5-F, 5.7-Me 2 ) with dithianediol 134.…”

“…When heated, compounds 144 and dithiane diol 145 in ethanol gave the expected spirocyclic products 146 in a short time in good yield ( Scheme 38). [202] …”