Synthesis of variously substituted allenediynes and their cobalt (I)-mediated [2+2+2] cycloaddition reactions
摘要:
Syntheses of variously substituted allenediynes where the allene moiety is at the terminal or internal position are described. Their cobalt(I)-mediated [2+2+2] cycloaddition reactions led to the corresponding eta(4)-complexed tricyclic compounds; the regioselectivity of these cyclizations depending on the substitution and the position of the allene is discussed. (C) 1998 Elsevier Science Ltd. Ali rights reserved.
halogenated cycloadducts via cyanation using copper and SNArreaction provides substituted selenopyridines with good yields. A novel synthetic method for the preparation of selenopyridine derivatives, involving a [2+2+2] cycloaddition of α,ω-diynes and selenocyanates that is catalyzed by a ruthenium complex is described. This mild and straightforward reaction allows access to a wide range of selenopyridines
作为有机合成中的特殊主题钌的一部分出版 抽象的 描述了一种制备硒吡啶吡啶衍生物的新颖合成方法,该方法涉及由钌配合物催化的α,ω-二炔和硒氰酸酯的[2 + 2 + 2]环加成。使用二氯甲烷或二氯乙烷作为溶剂,在50或80°C下,这种温和而直接的反应可以以高收率和优异的区域选择性获得各种硒吡啶。使用铜和S N Ar反应通过氰化作用将卤代环加合物进行后官能化,可提供具有良好收率的取代硒基吡啶。 描述了一种制备硒吡啶吡啶衍生物的新颖合成方法,该方法涉及由钌配合物催化的α,ω-二炔和硒氰酸酯的[2 + 2 + 2]环加成。使用二氯甲烷或二氯乙烷作为溶剂,在50或80°C下,这种温和而直接的反应可以以高收率和优异的区域选择性获得各种硒吡啶。使用铜和S N Ar反应通过氰化作用将卤代环加合物进行后官能化,可提供具有良好收率的取代硒基吡啶。
Ruthenium-Catalyzed [2 + 2 + 2] Cycloaddition Reaction Forming 2-Aminopyridine Derivatives from α,ω-Diynes and Cyanamides
A novel, efficient, and mild synthetic route for the preparation of 2-aminopyridines via ruthenium-mediated [2 + 2 + 2] cycloaddition of α,ω-diynes and cyanamides has been developed. This atom-economical catalytic process demonstrated remarkable regioselectivities to access pyridine derivatives of high synthetic utility.
Alkynyl chlorides, bromides, and iodides have been tested as [2 + 2 + 2] cycloaddition partners using CpCo(CO)(dimethylfumarate) and Cp*Ru(cod)Cl as precatalysts. A series of cocyclizations between diynyl dihalides and alkynes, as well as intramolecular cycloadditions of triynyl dihalides, has been carried out. While this study confirmed the versatility of the ruthenium complex with all kinds of halides
An addition/cyclization reaction of 1,6-diynes was developed for the synthesis of highly substituted 1,2-dialkylidenecycloalkanes. In this work, 1,6-diynes reacted with (dimethylphenylsilyl)pinacol-borane in the presence of a palladium catalyst to afford 1,2-dialkylidenecycloalkanes bearing silyl and boryl groups with a (Z,Z)-configuration in good to excellent yields. Moreover, the corresponding products
intramolecular rhodium(I)‐catalyzed [2+2+2] cycloaddition of allenynes with alkynes is described. A range of diverse polysubstituted benzene derivatives could be synthesized in good to excellent yields, in which the allenynes served as synthetic equivalent to the diynes. A high regioselectivity could be observed when allenynes were treated with unsymmetrical alkynes.