The additions of chlorine, bromine and bromine chloride to trans methyl 2-butenoate 1, trans methyl 2-methyl-2-butenoate 2 and methyl 3-methyl-2-butenoate 3 under ionic conditions were studied. Bromine chloride addition always gave as a major regioisomer the 2-bromo-3--chloro compound,almost quantitatively in the case of 3. The mechanism of bromoniumion ring-opening (SN1 or SN2) is discussed with
氯,溴和氯化溴到加法反式甲基-2-丁烯酸乙酯1,反式甲基-2-甲基-2-丁烯酸甲酯2和3-甲基-2-丁烯酸乙酯3离子的条件下进行了研究。氯化溴加成总是得到为主要区域异构体的2-溴-3 -氯化合物,在几乎定量的情况下,3。关于双键取代和区域异构体的比例,讨论了溴离子开环(S N 1或S N 2)的机理。通过MS,1 H和13 C NMR鉴定出二卤代产物。
Total Synthesis and Biological Evaluation of Zealactone 1a/b
well as in planta, evaluating its biological activities has been hampered by its low natural abundance and its relative chemical instability. Herein, we present the total synthesis of zealactone 1a/b based on our studies employing a [2+2]‐cycloaddition strategy and a chemoselective Baeyer‐Villiger oxidation to forge the γ‐butyrolactone fragment. Furthermore, we disclose the biological activities of zealactone
The reaction of alkynoates with aryl- or alkylboron reagents in the presence of a rhodium/diene catalyst gave high yields of salicylate derivatives with high selectivity, which consist of three or four molecules of the alkynoate and one organic group derived from the organoboron reagents.
The present invention provides novel compositions of matter and processes for their preparation. Particularly, the present invention relates to novel monocyclic β-lactams of formula I, having a carbonyl group, other than a negatively charged group, attached to the N-1 position. The compounds are useful as antimicrobial agents or as intermediates thereto. The present invention also provides a novel process for making these compounds which utilizes palladium (O)-catalyzed carbonylation of an appropriate 2-bromo-1-propen-3-yl amine and novel intermediates prepared by this process.
Further demonstration of the higher reactivity of the vinyl hydrogen rather than the allyl hydrogen towards singlet oxygen
作者:Hajime Mori、Keiichi Ikoma、Shigeo Katsumura
DOI:10.1039/a705924h
日期:——
In a new linear twisted 1,3-diene, an anomalously high reactivity of the vinyl hydrogen rather than the allyl hydrogen towards singlet oxygen is observed.