Silver-Catalyzed Isocyanide-Alkyne Cycloaddition: A General and Practical Method to Oligosubstituted Pyrroles
作者:Jianquan Liu、Zhongxue Fang、Qian Zhang、Qun Liu、Xihe Bi
DOI:10.1002/anie.201302024
日期:2013.7.1
key: The transition‐metal‐catalyzed cycloaddition of isocyanides and unactivated terminal alkynes has been realized with Ag2CO3 as a unique and robust catalyst (see scheme). The protocol is highly efficient, allowing a broad range of terminal and internal alkynes to react under base‐ and ligand‐free conditions, generating synthetically useful oligosubstitutedpyrroles in high yields.
Ag 2 CO 3是关键:Ag 2 CO 3是一种独特而坚固的催化剂,已经实现了过渡金属催化的异氰酸酯和未活化的末端炔烃的环加成反应(参见方案)。该方案非常高效,可以使各种末端和内部炔烃在无碱和无配体的条件下反应,从而以高收率生成合成上有用的寡取代吡咯。
Alkynyl−B(dan)s in Various Palladium‐Catalyzed Carbon−Carbon Bond‐Forming Reactions Leading to Internal Alkynes, 1,4‐Enynes, Ynones, and Multiply Substituted Alkenes
reactions can be achieved as more convenient one‐pot reactions, without isolating the alkynyl−B(dan) formed in situ by the zinc‐catalyzed dehydrogenative borylation of alkynes with HB(dan). In addition to direct C(sp)−B(dan) bond transformations, the C≡C bond in an alkynyl−B(dan) proved to be a promising scaffold for the construction of a multisubstituted alkene, which is synthesized by diboration of the
发现炔基-B(dan)s的C(sp)-B(dan)键可直接用于钯催化的芳基(烯基)卤化物和烯丙基碳酸酯作为亲电子试剂的碳-碳键形成反应,因此分别产生不对称的内部炔烃和未共轭的1,4-炔烃。使用酰氯作为亲电子试剂,钯催化剂在铜助催化剂的辅助下也可以促进炔酮的合成。这些反应可作为更方便的单锅反应来实现,而无需分离通过炔烃与HB(dan)进行锌催化脱氢硼化反应而原位形成的炔基-B(dan)。除了直接C(sp)-B(dan)键的转变,炔基-B(dan)中的C≡C键被证明是构建多取代烯烃的有前途的支架,该多取代烯烃通过C≡C-B(dan)的硼烷基化反应合成)部分,导致三硼烷基烯烃,随后发生区域和立体选择性的Suzuki-Miyaura交叉交叉偶联反应。举一个例子,合成具有四个不同芳基的乙烯,p- MeC 6 H 4,p- MeOC 6 H 4,p- NCC 6 H 4和p- F 3 CC 6 H 4
Bifunctional phosphine ligand-enabled gold-catalyzed direct cycloisomerization of alkynyl ketones to 2,5-disubstituted furans
An efficient synthesis of 2,5-disubstitutedfurans directly from alkynyl ketones has been developed via tandem gold(I)-catalyzed isomerization of alkynyl ketones to allenyl ketones and cycloisomerization. The key to the success of this chemistry is the use of a biphenyl-2-ylphosphine ligand featuring a critical remote tertiary amino group.