化学学报 ›› 2022, Vol. 80 ›› Issue (4): 432-437.DOI: 10.6023/A21120597 上一篇    下一篇

所属专题: 中国科学院青年创新促进会合辑

研究通讯

钯催化硼-碳和硼-杂原子键构建一锅法合成双官能团化邻-碳硼烷

葛懿修a, 邱早早a,*(), 谢作伟a,b   

  1. a 中国科学院上海有机化学研究所沪港化学合成联合实验室 上海 200032
    b 香港中文大学化学系 中国香港
  • 投稿日期:2021-12-29 发布日期:2022-04-28
  • 通讯作者: 邱早早
  • 作者简介:
    庆祝中国科学院青年创新促进会十年华诞.
  • 基金资助:
    国家自然科学基金(92056106); 香港研究资助局(14305018)

Pd-Catalyzed One-Pot Synthesis of Difunctionalized o-Carboranes via Construction of B—C and B—Heteroatom Bonds

Yixiu Gea, Zaozao Qiua(), Zuowei Xiea,b   

  1. a Shanghai-Hong Kong Joint Laboratory in Chemical Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032
    b Department of Chemistry, The Chinese University of Hong Kong, Hong Kong, China
  • Received:2021-12-29 Published:2022-04-28
  • Contact: Zaozao Qiu
  • About author:
    Dedicated to the 10th anniversary of the Youth Innovation Promotion Association, CAS.
  • Supported by:
    National Natural Science Foundation of China(92056106); Hong Kong Research Grants Council(14305018)

碳硼烷是由碳氢和硼氢顶点组成的笼状分子, 在医药、能源和材料等领域有着重要应用, 但目前在碳硼烷硼顶点引入杂原子取代基的方法还较为有限. 基于此, 本工作从3-碘-邻-碳硼烷出发, 通过钯催化烯基化、金属迁移及后续与杂原子亲核试剂的偶联反应, 一锅法构筑硼碳键和硼杂原子键, 成功实现了一系列新型3-烯基-4-胺基/烷氧基/烷(芳)硫基-邻-碳硼烷衍生物的合成.

关键词: 碳硼烷, 钯催化, 金属迁移, 硼-碳键, 硼-杂原子键

Icosahedral carboranes are carbon-boron molecular clusters, sharing many features with benzene such as aromaticity, high thermal and chemical stability. On the other hand, carboranes have their own unique characteristics like spherical geometry and three-dimensional electronic delocalization. These properties render carboranes unique building blocks for various applications ranging from versatile ligands to functional materials to medicine. In this regard, functionalization of carboranes, particularly regioselective functionalization of cage B-vertexes has recently received much attention. Based on our recently developed Pd-catalyzed iodine-migration on o-carborane cage, a Pd-catalyzed regioselective difunctionalization of 3-iodo-o-carborane in a one-pot manner has been achieved to afford a series of 3-alkenyl-4-Nu-o-carboranes (Nu=arylamino, alkoxyl, alkyl and arylthio) in 47%~99% yields. This protocol combines the sequential activation of cage B(3)—I and B(4)—H bonds by Pd migration, as well as further Pd-catalyzed transformation of B(4)—I bond, leading to the construction of B—C and B—Heteroatom bonds. A general procedure for the synthesis of 3-alkenyl-4-Nu-o-carboranes is described as follows: to a tetrahydrofuran (THF) solution (1 mL) of NuH (1.0 mmol) was added base (1.0 mmol) at 0 ℃ under an atmosphere of dry nitrogen. The reaction mixture was stirred for another 10 min to obtain the NuM solution (NuM=ArNHMgBr, base=EtMgBr; NuM=Ar2NLi, base=nBuLi). Another oven-dried Schlenk flask equipped with a stir bar was charged with 3-iodo-o-carborane (1, 27 mg, 0.1 mmol), Pd(PPh3)4 (12 mg, 0.01 mmol), diphenylacetylene (89 mg, 0.5 mmol) and dry toluene (1 mL) under an atmosphere of dry nitrogen. The flask was closed, and stirred at 80 ℃ for 72 h. Then, the resulting solution was cooled to 0 ℃, to which was slowly added NuM (0.15 mmol) (NuM=ArNHMgBr, Ar2NLi, tBuONa and RSNa). The reaction mixture was warmed to room temperature, and stirred at 80 ℃ for 24 h. After quenching with water (1 mL) and extraction with ethyl acetate (5 mL×3), the organic portions were combined and concentrated to dryness in vacuo. The residue was subjected to flash column chromatography on silica gel (300~400 mesh) using n-hexane as eluent to give the product.

Key words: carborane, palladium catalysis, metal migration, B—C bond, B—Heteroatom bond