Asymmetric intramolecular cyclopropanation of diazo compounds with metallosalen complexes as catalyst: structural tuning of salen ligand
摘要:
Intramolecular cyclopropanation of alkenyl alpha-diazoacetates and alkenyl diazomethyl ketones was examined by using optically active (ON+)Ru(11)(salen) and Co(II)(salen) complexes as catalysts. For the cyclization of 2-alkenyl alpha-diazoacetates, Co(II)(salen) complexes 9 and 10 were found to be superior catalysts to the corresponding (ON+)Ru(11)(salen) complexes 4 and 5. On the other hand, (ON+)Ru(II)(salen) complex 2 was found to be the catalyst of choice for the cyclization of 3-alkenyl diazomethyl ketones, and complex 4 was found to be a good catalyst for the cyclization of (E)-4-alkenyl diazomethyl ketones. The present study demonstrates that metallosalen complexes, especially optically active (ON+)Ru(II)(salen) and Co(11)(salen) complexes, can serve as efficient catalysts for the cyclization of alkenyl diazocarbonyl compounds, if a suitable salen ligand is used as the chiral auxiliary. (C) 2003 Elsevier Science Ltd. All rights reserved.
A convenient one-pot synthesis of homoallylic halides and 1,3-butadienes
作者:Ken-Tsung Wong、Ying-Yueh Hung
DOI:10.1016/j.tetlet.2003.07.006
日期:2003.10
An efficient one-pot synthetic pathway for the preparation of homoallylichalides by in situ generated MgBrCl-promoted ring opening of cyclopropylcarbinyl acetates has been established. An easily accessible one-pot synthetic protocol of 1,3-butadienes by the elimination of hydrogen halides from the resulting homoallylichalides in the presence of an excess amount of strong base has also been developed
Selective Reduction of Barbituric Acids Using SmI<sub>2</sub>/H<sub>2</sub>O: Synthesis, Reactivity, and Structural Analysis of Tetrahedral Adducts
作者:Michal Szostak、Brice Sautier、Malcolm Spain、Maike Behlendorf、David J. Procter
DOI:10.1002/anie.201306484
日期:2013.11.25
Making a mark: Since the 1864 landmark discovery by Adolf von Baeyer, barbituric acids have played a prominent role in organic synthesis. Herein, the first chemoselective monoreduction of barbituric acids to the corresponding hemiaminals is described. The method delivers mono‐ and bicyclic hemiaminal products by a general single‐electron‐transfer polarity reversal mechanism.
留下深刻印象:自 1864 年 Adolf von Baeyer 里程碑式的发现以来,巴比妥酸在有机合成中发挥了重要作用。本文描述了巴比妥酸首次化学选择性单还原为相应的半缩醛胺。该方法通过通用的单电子转移极性反转机制提供单环和双环半缩醛胺产物。
Studies on the Mechanism, Selectivity, and Synthetic Utility of Lactone Reduction Using SmI<sub>2</sub> and H<sub>2</sub>O
作者:Dixit Parmar、Lorna A. Duffy、Dhandapani V. Sadasivam、Hiroshi Matsubara、Paul A. Bradley、Robert A. Flowers、David J. Procter
DOI:10.1021/ja906396u
日期:2009.10.28
esters and lactones have long been thought to lie outside the reducing range of SmI(2), activation of the lanthanide reagent by H(2)O allows some of these substrates to be manipulated in an unprecedented fashion. For example, the SmI(2)-H(2)O reducing system shows complete selectivity for the reduction of 6-membered lactones over other classes of lactones and esters. The kinetics of reduction has been
Matveeva; Kvasha; Kurts, Russian Journal of Organic Chemistry, 1996, vol. 32, # 1, p. 17 - 20
作者:Matveeva、Kvasha、Kurts
DOI:——
日期:——
A Method for Synthesis of Homoallylic Bromide
作者:Wenke Qi、Peipei Wang、Liyuan Fan、Songlin Zhang
DOI:10.1021/jo400580n
日期:2013.6.21
Cyclopropyl Grignard reagents react with carbonyl compounds in the presence of diethyl phosphite to give homoallylicbromides. The reaction is effectively carried out under mild conditions in a one-pot fashion with moderate to good yields.