Retigeric acid A 是一种结构独特的五环二萜,带有八个立体中心。我们报告了 (-)-retigeric acid A 核心结构的简洁路线。其六个手性中心和三个季碳中心的立体化学得到了很好的控制。该路线具有两个分子内 Pauson-Khand 反应 (IMPKR):第一个锻造 D 和 E 环以传递三喹烷亚基,第二个构建 A 和 B 环并非对映选择性地安装四元 C 6a中心。
Palladium-catalyzed cross-coupling reactions between benzyl, aryl, or allyl bromides and conjugated ene-yne-ketones lead to the formation of 2-alkenyl-substituted furans. This novel coupling reaction involves oxidative addition, alkyne activation-cyclization, palladium carbene migratoryinsertion, β-hydride elimination, and catalyst regeneration. Palladium (2-furyl)carbene is proposed as the key intermediate
situ. This novel skeletal reorganization process was implemented into a concise total synthesis of the terpenes sabinone (18) and sabinol (19). Furthermore it is shown that conversion of the hydroxylatedenynes into the corresponding acetates followed by reaction with a cationic gold catalyst formed from (PPh3)AuCl and AgSbF6 opens entry into isomeric products bearing the ketone function at the C-2
Gold-catalyzed [4+1]-annulation reactions between anthranils and 4-methoxy-1,2-dienyl-5-ynes involving a 1,2-allene shift
作者:Hsiang-Chu Hsieh、Kuo-Chen Tan、Antony Sekar Kulandai Raj、Rai-Shung Liu
DOI:10.1039/c8cc09082c
日期:——
annulations involves nitrene formation of α-imino gold carbenes that undergo a 1,2-allene shift to form (pyrrol-2-yl) methylgold intermediates. With allenyl ester substrates, these gold intermediates become enolate species to enable intramolecular aldol reactions to form useful pyrrolo[1,2-a]quinoline derivatives.
描述了金催化的4-甲氧基-1,2-二烯基-5-炔基与蒽的[4 + 1]环。这些成环的机理涉及α-亚氨基金卡宾的腈形成,其经历1,2-丙二烯转变以形成(吡咯-2-基)甲基金中间体。在具有烯丙基酯底物的情况下,这些金中间体成为烯醇化物物种,从而使分子内的醛醇缩合反应能够形成有用的吡咯并[1,2- a ]喹啉衍生物。
Pd-catalyzed cross-coupling of terminal alkynes with ene-yne-ketones: access to conjugated enynes via metal carbene migratory insertion
作者:Ying Xia、Zhen Liu、Rui Ge、Qing Xiao、Yan Zhang、Jianbo Wang
DOI:10.1039/c5cc03559g
日期:——
Pd-catalyzed oxidative cross-coupling of terminal alkynes with ene-yne-ketones has been developed, in which the ene-yne-ketones are served as carbene precursors and metal carbene migratory insertion process is the key step for C–C bond formation.
Palladium-catalyzed oxidative borylation of conjugated enynones through carbene migratory insertion: synthesis of furyl-substituted alkenylboronates
作者:Yifan Ping、Taiwei Chang、Kang Wang、Jingfeng Huo、Jianbo Wang
DOI:10.1039/c8cc09024f
日期:——
enynones is developed. This reaction represents a new method for the synthesis of furyl-substituted alkenylboronates. The reaction works well with a series of conjugated enynones. Boryl migratoryinsertion of the palladium carbene intermediate is proposed as the key step in these transformations.