WingPhos, a C2‐symmetric bisphosphorus ligand with a deep and well‐defined chiral pocket was developed. It has shown high efficiency in the rhodium‐catalyzed asymmetrichydrogenation of (E)‐β‐aryl‐N‐acetyl enamides, cyclic β‐aryl enamides, and heterocyclic β‐aryl enamides. A series of chiral β‐arylisopropylamines, 2‐aminotetralines, and 3‐aminochromans can be synthesized with excellent ee values (nbd=3
WingPhos是一种C 2对称的双磷配体,具有较深且定义明确的手性口袋。在(E)-β-芳基-N-乙酰基酰胺,环状β-芳基酰胺和杂环β-芳基酰胺的铑催化不对称氢化反应中显示出很高的效率。可以合成一系列具有良好ee值(nbd = 3,5-降冰片二烯; TON =周转数)的手性β-芳基异丙胺,2-氨基四氢呋喃和3-氨基苯并二氢吡喃。
Reaction of β-nitrostyrenes with benzene catalyzed by trifluoromethanesulfonic acid. Formation and reaction of n,n-dihydroxyiminium-benzyl dications
作者:Tomohiko Ohwada、Toshiharu Ohta、Koichi Shudo
DOI:10.1016/s0040-4020(01)89957-9
日期:1987.1
β-Nitrostyrenes are diprotonated on the nitrogroup to yield N,N-dihydroxyiminium-benzyl dications in trifluoromethanesulfonicacid. These dications comprise a new class of reagents that can react with benzene. The reaction is dependent on the substituent (H or alkyl group) at the β-position of nitrostyrene: β-nitrostyrene yields diphenylacetophenoneoxime, and β-methyl-β-nitrostyrene yields acetophenoneoxime
2-Silyloxy-1,2-oxazines, a New Type of Acetals of Conjugated Nitroso Alkenes
作者:Alexander A. Tishkov、Alexey V. Lesiv、Yulya A. Khomutova、Yury A. Strelenko、Ivan D. Nesterov、Michael Yu. Antipin、Sema L. Ioffe、Scott E. Denmark
DOI:10.1021/jo034669a
日期:2003.11.1
3-alkyl-substituted 1,2-oxazine N-oxides 2 can be selectively transformed into 2-silyloxy-1,2-oxazines 1 upon treatment with silylating reagents. In the solidstate derivatives 1 adopt a chair conformation with the pyramidal nitrogen atom, whereas in solution they exist as an equilibrating mixture of two conformers (DeltaG++ 55-60 kJ/mol). A preliminary study of the reactivity of nitrosals 1 has shown
作者:Peter J. S. S. van Eijk、Cor Overkempe、Willem P. Trompenaars、David N. Reinhoudt、Lauri M. Manninen、Gerrit J. van Hummel、Sybolt Harkema
DOI:10.1002/recl.19881070202
日期:——
yield the trans four-membered cyclic nitrones 12–13 upon reaction with 6. Nitroalkene 4i reacts with 6c to give a 1:1 mixture of the cis and trans four-membered cyclic nitrones 9g and 13i. The trans stereochemistry of trans-N,N-diethyl-2, 3-dihydro-3-(2-methoxynaphthalenyl)-2-methyl-4-phenyl-2-azetecarboxamide 1-oxide (13k) was elucidated by means of X-ray analysis. Only from the reaction of 1-nitrocyclopentene
Scope and Limitations of the Nitro-Mannich Reaction for the Stereoselective Synthesis of 1,2-Diamines
作者:James C. Anderson、Alexander J. Blake、Gareth P. Howell、Claire Wilson
DOI:10.1021/jo048304h
日期:2005.1.1
p-methoxybenzyl (PMB) or p-methoxyphenyl (PMP) in the Lewis acid-catalyzed addition reactions. Reduction with SmI2, treatment with COCl2, followed by OMB deprotection gave diastereomerically pure cis-imidazolidinones in 55−79% overall yield from imine. Preliminary results have shown that acetic acid can catalyze the reaction of N-OMB-benzylideneamine with nitropropane, used as solvent, to give the thermodynamically
乙酸促进的硝基丙酸锂的加成反应和路易斯酸催化的[Sc(OTf)3,Cu(OTf)2或Ti(O i Pr)4)的加成反应生成三甲基甲硅烷基硝基丙酸酯到一系列杂芳族和简单的脂肪族醛亚胺中以> 95%的收率得到抗富集的(〜3-19:1)β-硝胺,为动力学产物。发现在路易斯酸催化的加成中,非极性N-亚胺保护基对于与邻甲氧基苄基(OMB)的反应性至关重要,与对甲氧基苄基(PMB)或对甲氧基苯基(PMP)相比,具有更好的选择性和更高的收率。反应。减少SmI 2,用COCl 2处理,再用OMB脱保护,得到非对映体纯的顺式-咪唑啉酮,其亚胺的总产率为55-79%。初步结果表明,乙酸可以催化N -OMB-亚苄基胺与用作溶剂的硝基丙烷的反应,从而提供热力学上更稳定的顺式-β-硝基胺产物。