An efficient RhII -catalyzed synthesis of functionalized α-vinyl aldehydes with high E/Z stereoselectivity was developed. The reaction mediates the cyclopropanation of enaminones with vinyl carbenoids that are generated from cyclopropenes in situ to give the aminocyclopropane intermediates. Selective C-C bond cleavage of the cyclopropane intermediates leads to formation of α-vinyl aldehyde derivatives
Total Synthesis of (�)-Clovene. On the Stereoelectronic Requirements of the ?-Alkynone Cyclisation
作者:John Ackroyd、Martin Karpf、Andr� S. Dreiding
DOI:10.1002/hlca.19840670735
日期:1984.11.7
The synthesis of the sequiterpenoid tricyclic hydrocarbon (±)-cleovene (1) by application of the α-alkynone cyclisation is described. The starting bicyclic carboxylic acid 2 was obtained from ethyl 3-methyl-2-oxocyclohexane-1-carboxylate by modified known methods (24%) and converted to the α-alkynone 3 (86%). The thermolysis of 3 in the gas phase at 620° selectively produced the tricyclo[6.3.1.01,5]
gem-difluorinated 2H-furans from reactions of BrCF2CO2Et with enaminones has been described. The reactions tolerate a wide variety of functional groups under metal-free conditions. An active aminocyclopropane is proposed to be a key intermediate through the cyclopropanation of difluorocarbene with enaminones, which further triggers a regioselective C–C bond cleavage in situ to afford the corresponding gem-difluorinated
已经描述了由 BrCF 2 CO 2 Et 与烯胺酮反应合成偕二氟化 2 H-呋喃的级联策略。该反应在无金属条件下耐受多种官能团。通过二氟卡宾与烯胺酮的环丙烷化反应,活性氨基环丙烷被认为是关键中间体,这进一步引发了区域选择性 C-C 键原位断裂,得到相应的偕二氟化2 H-呋喃。
Synthesis of 2,3-Disubstituted pyrroles by Lewis acid promoted cyclization of N-Sulfonyl vinylogous carbamates and amides
作者:Gavin J. Rustin、Matthew G. Donahue
DOI:10.1016/j.tetlet.2023.154507
日期:2023.6
three components including 2,2-dimethoxyethylamine, aryl/alkyl sulfonyl chlorides and alkynes bearing electron-withdrawing groups is presented. The pyrroles are proposed to arise via a 5-exo-trig cyclization proceeding through both oxocarbenium and N-sulfonyliminium ions. This modular route allows for the variability at the N-sulfonyl group, the C2 and C3 substituents for rational vectoring of the pyrrole
介绍了从 2,2-二甲氧基乙胺、芳基/烷基磺酰氯和带有吸电子基团的炔烃等三种组分构建吡咯的三步序列。吡咯被认为是通过氧碳鎓和N-磺酰亚胺离子进行的5- exo -trig 环化产生的。这种模块化路线允许N-磺酰基、 C 2 和 C3 取代基的可变性,以便为下游过程的吡咯核进行合理矢量化。
Enantioselective Addition of Allylzinc Reagent to Alkynyl Ketones