Intramolecular cyclopropanation reactions en route to novel P-heterocycles
摘要:
The first examples of intramolecular cyclopropanation reactions on a phosphonate template catalyzed by Rh-2(OAc)(4) are described. These reactions proceed in excellent yield and give mixtures of the P-heterocycles cis-2a-d and trans-2a-d with moderate levels of diastereoselectivity. The diastereoselectivity of this transformation is dependent upon the size of the alkyl group R contained in the alkyl alpha-diazodiallylphosphonoacetate starting materials 1a-d. (C) 1999 Elsevier Science Ltd. All rights reserved.
The substituent effect on the geometrical selectivity in the Horner–Wadsworth–Emmons (HWE) reaction was studied employing several mixed phosphonoacetates. Their reactions with aromaticaldehydes showed a gradual change in Z-selectivity according to the electron-withdrawing ability of the phosphonate substituents, and there was a good correlation between the observed selectivities and 31P chemical shifts
Phosphorylated methano[60]fullerenes containing nitroxyl radicals: synthesis, structures, and electrochemical behavior
作者:V. P. Gubskaya、L. Sh. Berezhnaya、V. V. Yanilkin、V. I. Morozov、N. V. Nastapova、Yu. Ya. Efremov、I. A. Nuretdinov
DOI:10.1007/s11172-006-0017-5
日期:2005.7
one or two nitroxyl radicals were synthesized for the first time. Their structures were established from spectroscopic data and their compositions, by MALDI-TOF mass spectrometry. Their electrochemicalreduction in a system o-dichlorobenzene-DMF/0.1 M Bu4NBF4 was studied by cyclic voltammetry, preparative electrolysis, and ESR spectroscopy in combination with in situ electrolysis. Both compounds were
首次合成了含有一个或两个硝酰基自由基的磷酸化甲烷[60]富勒烯。它们的结构是通过 MALDI-TOF 质谱法从光谱数据及其组成确定的。通过循环伏安法、制备电解和 ESR 光谱结合原位电解研究了它们在邻二氯苯-DMF/0.1 M Bu4NBF4 系统中的电化学还原。发现这两种化合物都经历了富勒烯球的四步还原、硝酰基的还原、三元环的打开以及作为通过质子化和重排为磷酸根离子和取代乙炔而稳定的碳负离子的加数消除,伴随着形成游离富勒烯和二氢呋喃富勒烯。随着富勒烯球上负电荷的增加,开环率和加数消除率增加。在转移三个电子的情况下,这些反应很快。使用模型化合物,揭示了在第三个电子转移到富勒烯球的电位下向硝酰基自由基的异质电子转移和从富勒烯球的二价阴离子转移的均匀分子内电子转移。讨论了观察到的转换的机制。揭示了在第三电子转移到富勒烯球的电位下向硝酰基自由基的异质电子转移和从富勒烯球的二价阴离子的均匀分子内电
Stereoselective Synthesis of the Benzodihydropentalene Core of the Fijiolides
作者:Timon Kurzawa、Klaus Harms、Ulrich Koert
DOI:10.1021/acs.orglett.8b00163
日期:2018.3.2
benzodihydropentalene core of fijiolides A and B has been achieved. The asymmetric conjugate addition of styrylboronic acid to an indenone produced the first stereocenter. Ring C was installed by ring-closing metathesis of a cis disubstituted indanone. Regioselective epoxide opening by NaSePh and subsequent oxidative elimination produced an allylic alcohol. The final introduction of the cyclopentadiene was possible
Proton exchange and chemoselectivity in metal cation and hydroxide ion hydrolyses of phosphonoacetate diesters
作者:Robert A Moss、Paul K Gong
DOI:10.1016/j.tetlet.2003.07.005
日期:2003.10
Phosphonoacetate diesters exhibit base catalyzed D/H proton exchange and C-OR esterolysis, as well as (acidic) hydrolyses mediated by Th4+ and Zr4+ ions.
New phosphonoacyl prolines and related compounds have the general formula ##STR1## wherein R.sub.1 and R.sub.2 each is hydrogen, lower alkyl, lower alkenyl, unsustituted or substituted phenyl-lower alkyl, or a metal ion; R.sub.3 is hydrogen or lower alkyl; R.sub.4 is hydrogen, lower alkyl, phenyl-lower alkyl or a metal ion; and N is 0 or 1. These compounds are useful as hypotensive agents.