Asymmetric silyl nitronate cycloadditions with bornane-10,2-sultam derivatives
摘要:
Asymmetric silyl nitronate cycloadditions with N-acryloyl (2R)-bornane-10,2-sultam, N-acryloyl (2S)-bornane-10,2-sultam, and N-methacryloyl (2R)-bornane-10,2-sultam have been studied. The asymmetric silyl nitronate cycloaddition/elimination methodology provides a general route for the asymmetric synthesis of 2-isoxazolines.
Catalytic Asymmetric Synthesis of Isoxazolines from Silyl Nitronates
摘要:
1,3-Dipolar Cycloadditions of triisopropylsilyl intronates and 2-alkylacroleins produced isoxazolines bearing a chiral quaternary center in high yields-and enantioselectivities with the aid of a chiral oxazaborolidine catalyst. One chiral isoxazoline product was converted to (R)-(+)-Tanikolide in 9 steps in a total yield of 43%.
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。
Reactions of nitronates derived from simple nitro alkanes with some thio-stabilized cationic intermediates
作者:I. M. Lyapkalo、M. I. Lazareva、A. D. Dil'man、S. L. Ioffe、W. A. Smit
DOI:10.1007/bf02496167
日期:1999.3
Trimethylsilyl and DBU nitronates derivedfrom nitromethane and nitropropanes do not undergoC-alkylation by episulfonium (ESI) or thiophanium (TPI) cationic intermediates. The above-mentioned derivatives of 1-nitropropane react with ESI and TPI to give the corresponding products ofO-alkylation of 1-chloro-1-oxyiminopropane. The reactions of DBU nitronates derivedfrom nitromethane and 2-nitropropane
Highly Enantioselective Michael Addition of Silyl Nitronates to α,β-Unsaturated Aldehydes Catalyzed by Designer Chiral Ammonium Bifluorides: Efficient Access to Optically Active γ-Nitro Aldehydes and Their Enol Silyl Ethers
作者:Takashi Ooi、Kanae Doda、Keiji Maruoka
DOI:10.1021/ja0352810
日期:2003.7.1
Highly enantioselective Michaeladdition of silyl nitronates to α,β-unsaturated aldehydes has been accomplished by the utilization of designer N-spiro C2-symmetric chiral quaternary ammonium bifluoride 1 as an efficient catalyst, providing direct access to both optically active γ-nitro aldehydes, a very useful precursor to various complex organic molecules including aminocarbonyls, and their enol silyl
Trimethylsilyl derivatives of aliphatic nitro compounds in α,β-C,C-cross-coupling
作者:A. D. Dilman、I. M. Lyapkalo、S. L. Ioffe、Yu. A. Strelenko、V. A. Tartakovsky
DOI:10.1007/bf02494712
日期:2000.5
A new α,β-C,C-cross-coupling reaction of derivatives of aliphatic nitrocompounds, silyl nitronates andN,N-bis(silyloxy)enamines, leading to β-nitro oximes was found. The scope and limitations of this reaction were studied, and a mechanism was proposed.
An Asymmetric Nitro-Mannich Reaction Applicable to Alkyl, Aryl, and Heterocyclic Imines
作者:James C. Anderson、Gareth P. Howell、Ron M. Lawrence、Claire S. Wilson
DOI:10.1021/jo050762i
日期:2005.7.1
A protocol for the enantioselective nitro-Mannich coupling between alkyl, aryl, and heterocyclic p-methoxybenzylimines and trimethylsilylnitropropanate catalyzed by a chiral tBu-BOX Cu(II) catalyst is described. It uses the lowest reported loading of commercially available metal catalyst and chiral ligand, and gives the highest yields and selectivities for a broad substrate range including nonaromatic