Organoselenium- and proton-mediated cyclization reactions of allylic amides and thioamides. Syntheses of 2-oxazolines and 2-thiazolines
摘要:
A variety of allylic amides and thioamides were treated with phenylselenenyl bromide in chloroform to give, via 5-exo cyclization, 2-oxazolines and 2-thiazolines, respectively, carrying a (phenylselenenyl)methyl substituent in the 5-position. In some cases (N-crotyl- and N-cinnamylamides/thioamides), dihydro-1,3-oxazines/-thiazines were formed via 6-endo cyclization. The phenylselenenyl group of the cyclofunctionalization products was slowly eliminated by treatment with m-chloroperbenzoic acid to introduce unsaturation in the resulting oxazoline/thiazoline. Reductive removal of the phenylselenenyl group was effected by treatment with triphenyltin hydride. This reaction was sometimes accompanied by a rearrangement of the heterocyclic ring. Proton-induced cyclizations of allylic thioamides to give 2-thiazolines was slowly but efficiently effected in boiling toluene containing a catalytic amount of p-toluenesulfonic acid.
Cobalt-Catalyzed Allylation of Amides with Styrenes Using DMSO as Both the Solvent and the α-Methylene Source
作者:Xu Zhang、Zhi Zhou、Huiying Xu、Xuefeng Xu、Xiyong Yu、Wei Yi
DOI:10.1021/acs.orglett.9b02462
日期:2019.9.20
An efficient synthesis of privileged allylic amines has been developed via cobalt-catalyzed allylation of amides with styrenes, in which DMSO was used as both the solvent and the α-methylene source. This transformation features high yields, and selectivity for the (E)-isomer of the linear product. Through the experimental and computational investigations, a sequential K2S2O8-mediated oxidative cou
通过将酰胺与苯乙烯进行钴催化的烯丙基化反应,已经开发了一种有效的特权烯丙基胺的合成方法,其中DMSO既用作溶剂,又用作α-亚甲基源。该转化具有高收率和对线性产物的(E)-异构体的选择性。通过实验和计算研究,还推导了顺序的K 2 S 2 O 8介导的氧化偶联/钴辅助的区域选择性烯烃插入/β-H消除/烯烃解离/氢化物转移过程。
Relay Catalysis by a Metal-Complex/Brønsted Acid Binary System in a Tandem Isomerization/Carbon−Carbon Bond Forming Sequence
作者:Keiichi Sorimachi、Masahiro Terada
DOI:10.1021/ja807591m
日期:2008.11.5
one-pot tandem isomerization/carbon-carbon bond forming sequence catalyzed by a ruthenium complex/Brønstedacidbinarysystem is demonstrated. The method enables the use of readily available allylamides to deliver reactive imines under relaycatalysisusing a binary catalytic system. Subsequent Brønstedacid catalyzed carbon-carbon bond forming reactions of the generated imines with nucleophilic components
mL of toluene, Rh(acac)(CO)2 as the metal precursor, (S,R)-(N-Bn)Yanphos as the ligand, CO:H2 = 10:10 bar, S/C = 20, HSiEt3 (0.3 mmol), and BF3.Et2O (0.3 mmol) The configuration of all of the products was determined to be S, except for 4m; only the desired regioisomer was obtained as determined by NMR analysis. Scheme 4. Synthetic Transformations Addition/Correction
反应以 0.1 mmol 规模在 0.5 mL 甲苯中进行,Rh(acac)(CO)2 作为金属前体,(S,R)-(N-Bn)Yanphos 作为配体,CO:H2 = 10: 10 bar, S/C = 20, HSiEt3 (0.3 mmol), and BF3.Et2O (0.3 mmol) 通过NMR分析确定仅获得所需的区域异构体。方案 4. 合成变换加法/校正
Rhodium/Yanphos-Catalyzed Asymmetric Interrupted Intramolecular Hydroaminomethylation of <i>trans</i>-1,2-Disubstituted Alkenes
The first interruptedasymmetrichydroaminomethylation reaction was developed. The challenging trans-1,2-disubstituted olefins were employed as substrates, and a series of valuable chiral pyrrolidinones and pyrrolidines were obtained in high yields with high regioselectivities and excellent enantioselectivities. Several synthetic transformations were conducted, demonstrating the high synthetic utility