Highly functionalized oxazinanes are efficiently prepared through urea-catalyzed formal [3 + 3] cycloaddition reactions of nitrones and nitrocyclopropane carboxylates. The reaction system is general with respect to both the nitrocyclopropane carboxylates and nitrones enabling the preparation of a large family of oxazinanes, typically in high yield. This method affords access to enantioenriched oxazinane products through chirality transfer from enantioenriched nitrocyclopropane carboxylates.
Doubly Activated Cyclopropanes as Synthetic Precursors for the Preparation of 4-Nitro- and 4-Cyano-dihydropyrroles and Pyrroles
作者:Ryan P. Wurz、André B. Charette
DOI:10.1021/ol050442l
日期:2005.6.1
ketones have been prepared in an expedient manner from cyclopropanation reactions of alkenes by diazo compounds or in situ-generated phenyliodonium ylides catalyzed by Rh(II) carboxylates. The doubly activated cyclopropanes were used as synthetic precursors for the regiospecific synthesis of 4-nitro- and 4-cyano-dihydropyrroles upon treatment with primaryamines. Oxidation of the dihydropyrroles with DDQ
Catalytic asymmetric synthesis of nitrocyclopropane carboxylates
作者:Benoît Moreau、Dino Alberico、Vincent N.G. Lindsay、André B. Charette
DOI:10.1016/j.tet.2011.05.113
日期:2012.4
A Cu(I)-catalyzed asymmetric cyclopropanation of alkenes with an iodonium ylide has been developed. The copper source, hypervalent iodine source, solvent, and additives all have a significant effect on the yields and enantioselectivities. High enantioselectivity (up to 99:1 er) and diastereoselectivity (95:5 dr trans/cis) were achieved for a wide range of alkenes. Conditions were developed to convert
Expedient Synthesis of Cyclopropane α-Amino Acids by the Catalytic Asymmetric Cyclopropanation of Alkenes Using Iodonium Ylides Derived from Methyl Nitroacetate
作者:Benoît Moreau、André B. Charette
DOI:10.1021/ja056192l
日期:2005.12.1
A highly enantioselective (up to 97.5% ee) and diastereoselective (95:5 dr trans/cis) Cu(I)-catalyzed cyclopropanation of alkenes using phenyliodonium ylide generated in situ from iodosobenzene and methyl nitroacetate is reported. The cyclopropanation took place with high enantioselectivity for a wide range of alkenes, and the reaction was performed at room temperature. 1-Nitrocyclopropyl esters are
据报道,使用由碘代苯和硝基乙酸甲酯原位生成的苯基碘鎓叶立德,对烯烃进行了高度对映选择性(高达 97.5% ee)和非对映选择性(95:5 dr 反式/顺式)Cu(I)催化的烯烃环丙烷化反应。环丙烷化反应对多种烯烃具有高对映选择性,反应在室温下进行。1-硝基环丙基酯是通用的结构单元,可分别通过两步和三步从市售产品中获得相应的环丙烷氨基酯和氨基环丙烷。