Oxonia-Cope Rearrangement and Side-Chain Exchange in the Prins Cyclization
摘要:
[GRAPHICS]Evidence is presented here for the mechanism of the Prins cyclization of benzylic homoallylic alcohols, which shows that the outcome of the reaction is dependent upon the substituents on the aromatic ring. The presence of an electron-rich aromatic ring favors an oxonia-Cope rearrangement yielding a symmetrical tetrahydropyran as the major product formed via a side-chain exchange process. In contrast, with electron-deficient aromatic rings the expected 2,4,6-trisubstituted tetrahydropyran is formed.
Copper‐Impregnated Magnesium‐Lanthanum Mixed Oxide: A Reusable Heterogeneous Catalyst for Allylation of Aldehydes and Ketones
作者:Jaya Pogula、Soumi Laha、B. Sreedhar、Pravin R. Likhar
DOI:10.1002/adsc.201901133
日期:2020.3.4
Copper‐impregnated magnesium‐lanthanum mixed oxide [Cu(II)/Mg−La] was used as catalyst in synthesis of homoallylic alcohols from aldehydes and ketones using allyltributylstannane as the allylating source. The present protocol provides a great application potential for the synthesis of corresponding allyl alcohols with excellent yields and selectivity. The catalyst exhibits broad functional group compatibility
of manganese as a mediator for allylations and pinacol couplings in aqueousmedia was investigated. The combination of manganese and copper is found to be a highly effective mediator for the allylation of aryl aldehydes in water. Such a combination is found to be more reactive than other previously reported metals in aqueousmedia. No reaction was observed with either manganese or copper alone as the
Magnesium-Mediated Carbon−Carbon Bond Formation in Aqueous Media: Barbier−Grignard Allylation and Pinacol Coupling of Aldehydes
作者:Wen-Chun Zhang、Chao-Jun Li
DOI:10.1021/jo982497p
日期:1999.4.1
alkylation of aldehydes with alkyl halides was studied in aqueousmedia. The reaction of aromatic aldehydes with allyl halides is highly effective with either THF or water as the reaction solvent but poor in a mixture of THF/water. It was found that the magnesium-mediated allylation of aldehydes with allyl bromide and iodide proceeds effectively in aqueous 0.1 N HCl or 0.1 N NH(4)Cl. Aromatic aldehydes reacted
在含水介质中研究了镁介导的Barbier-Grignard型醛与烷基卤化物的烷基化反应。用THF或水作为反应溶剂,芳族醛与烯丙基卤的反应非常有效,但是在THF /水的混合物中效果较差。已经发现,镁与烯丙基溴和碘的醛介导的烯丙基化在0.1 N HCl或0.1 N NH(4)Cl水溶液中有效进行。芳族醛在脂肪族醛的存在下发生化学选择性反应。当脂族和芳族醛官能团同时存在于同一分子中时,也观察到排他选择性。在不存在烯丙基卤的情况下,醛和酮与镁在0.1 N NH(4)Cl水溶液中反应形成高产率的相应频哪醇偶联产物。频哪醇反应的有效性受到羰基周围空间环境的强烈影响。脂肪醛和简单的烷基卤化物在用于烷基化或频哪醇偶联反应的反应条件下呈惰性。
Copper-mediated oxysulfonylation of alkenyl oximes with sodium sulfinates: a facile synthesis of isoxazolines featuring a sulfone substituent
作者:Li-Jing Wang、Manman Chen、Lin Qi、Zhidong Xu、Wei Li
DOI:10.1039/c7cc00090a
日期:——
A novel and efficient Cu(OAc)2-mediated oxysulfonylation of alkenyl oximes with sodium sulfonates was developed. The reactions are easy to conduct, occur under mild conditions, and form a broad range of...
Palladium-Catalyzed Allylation of Carbonyl Compounds with Various Allylic Compounds Using In-InCl<sub>3</sub>in Aqueous Media
作者:Youseung Kim、Taeg-Su Jang、Gyochang Keum、Soon Bang Kang、Bong Young Chung
DOI:10.1055/s-2003-38059
日期:——
Various allylic compounds can be effectively applied to palladium-catalyzed allylation of carbonylcompounds via the formation of π-allylpalladium(II) intermediates and their transmetalation with indium in the presence ofindium trichloride in aqueousmedia.
各种烯丙基化合物可以有效地应用于钯催化的羰基化合物的烯丙基化反应,通过在水介质中三氯化铟存在下形成 π-烯丙基钯 (II) 中间体及其与铟的金属转移反应。