Asymmetric annulations based on cycloisomerization of cyclopropyl tethered allenyl ketones by bimetallic relay catalysis

Science China Chemistry, Journal Year: 2023, Volume and Issue: 66(10), P. 2803 - 2809

Published: Sept. 7, 2023

Language: Английский

---

N-Heterocyclic Carbene-Catalyzed Synthesis of Pentafluorophenyl Sulfides

Chinese Journal of Organic Chemistry, Journal Year: 2024, Volume and Issue: 44(2), P. 622 - 622

Published: Jan. 1, 2024

An efficient method for the construction of C(sp 2 )-S bond has been developed.The stable N-heterocyclic carbene 1,3-bis(2,6-dissopropylphenyl)-imidazole-2-ylidene can activate C -Si pentafluorophenyl trimethylsilicon effectively to initiate nucleophilic substitution reaction with thiosulfonic ester, producing sulfide products in 34%～98% yields.Keywords carbene; C-S bond; 碳-硫(C-S)键广泛存在于天然产物、生物活性化 合物、药物以及功能材料中, 因此 键的构建一直 是有机合成领域中的研究热点 [1] .在过去几十年中, 过 渡金属催化的交叉偶联反应、插入反应、硫代羰基化、 亲核加成反应等已经被广泛地用于 键的构建 [2] .另外, 多氟芳烃很多为重要的结构单元, 广泛存在于药 物分子和聚合物中, 因此合成五氟芳基硫醚化合物在有 机化学中具有重要意义 [3] .在过去的几十年里, 化学家 发展了几种合成五氟苯基硫醚化合物的方法.Kita 课题 组 [4] 在 2001 年通过 TMSOTf 催化富电子芳烃与醌单-O,S-缩醛的亚磺酰化和亲核加成反应获得了五氟苯基 硫醚化合物, 但该反应需要在低温条件下进行(Scheme 1a).Shi 课题组 [5] 用 Cu(I)催化五氟苯与二芳基二硫醚发 生交叉偶联反应(Scheme 1b), 得到相应的五氟苯基硫 醚, Peng [6] Ni(0)催化硫醇和芳基碘化物分子间 交叉偶联反应快速地合成了多种五氟苯基硫醚(Scheme Sakai [7] Pd(II)/Cu(II)催化二芳基二硫醚与 芳烃的交叉偶联反应(Scheme 得到五氟苯基硫醚 化合物.此外, Shibata [8] 通过活化的 α-亚甲基酮、 环状 1,3-二酮、 内酰胺和内酯与 6 F 5 -DAST 的脱酰基五 氟苯基硫化反应(Scheme 得到五氟苯基环硫醚衍 生物.然而这些方法一般都需要过渡金属催化剂催化, 有的还需要高温等较为苛刻的反应条件.我们课题组 [9] 前期利用膦腈碱 t-Bu-P 4 作为强有机 Lewis 碱催化剂, 实 现了有机小分子催化下五氟苯基硅试剂与硫代磺酸酯 的亲核取代反应(Scheme 1c), 制备了多种五氟苯基硫醚 化合物, 但膦腈碱催化剂价格非常昂贵, 在实验室制备 困难, 且该催化剂对水和空气高度敏感, 实验操作需要 极其严苛的无水无氧条件.因此, 该方法的实际应用受 到了一定的限制.

Language: Английский

---

NHC-catalyzed formal [3 + 3] annulations of δ-acetoxy allenoates for the synthesis of 4H-pyran derivatives

Organic & Biomolecular Chemistry, Journal Year: 2023, Volume and Issue: 21(28), P. 5775 - 5783

Published: Jan. 1, 2023

Herein, an N-heterocyclic carbene (NHC) catalyzed formal [3 + 3] annulation of δ-acetoxy allenoates with 1C,3O-bisnucleophiles for the construction 4H-(fused)pyrans has been developed. This protocol provides a facile method to synthesize highly functionalized 4H-pyrans and broad substrate scope (30 examples, up 77% yield).

Language: Английский

---

NHC‐Catalyzed [3+3] cycloaddition of 2‐(acetoxymethyl)buta‐2,3‐dienoates with 1C,3O‐bisnucleophiles

Asian Journal of Organic Chemistry, Journal Year: 2024, Volume and Issue: unknown

Published: Oct. 9, 2024

Abstract Diverse transformations of allenoates catalyzed by Lewis bases have emerged as a powerful platform for generating new chemical entities in organic synthesis. Herein, an N ‐heterocyclic carbene (NHC) [3+3] cyclization 2‐(acetoxymethyl)buta‐2,3‐dienoates with 1 C,3O‐bisnucleophiles has been developed. This approach provides facile method to synthesize highly functionalized 4 H ‐pyran derivatives broad substrate scope (31 examples, up 83 % yield).

Language: Английский

---

NHC-catalyzed regiodivergent transformations of Ynones with trifluoromethyl ketones: Aldol reaction or [3+2] annulation

Tetrahedron Chem, Journal Year: 2023, Volume and Issue: 7, P. 100044 - 100044

Published: Aug. 1, 2023

A novel NHC-catalyzed regiodivergent reaction of ynones with trifluoromethyl ketones consisting Aldol reactions and intermolecular [3 + 2] annulations has been developed. Employing two different NHC catalysts, various tertiary alcohols dihyrofuranones containing can be obtained in moderate to good yields (35 examples, up 91% yield). This protocol features mild conditions, high efficiency broad substrates scope, promoting the development catalysis transformations ynones.

Language: Английский

---

Six-membered ring systems: With O and/or S atoms

Progress in heterocyclic chemistry, Journal Year: 2023, Volume and Issue: unknown, P. 493 - 568

Published: Jan. 1, 2023

Language: Английский

---