二亚苄基丙酮(8)与原位生成的烯丙基卤化试剂反应生成均烯丙基环丙烷化反应的产物:2-(3''-丁烯基)-1,1-双[(E)-2'-苯基乙烯基]环丙烷(9),其通过逐步分离CO键和从试剂中递送两个烯丙基片段来进行。已经测试了一系列对映体富集的配体作为该过程的化学计量不对称改性剂。对映纯化合物,例如金鸡纳生物碱,麻黄,氨基醇和酒石酸衍生物,已被证明可用作铟介导的醛和酮的烯丙基化的不对称改性剂,但在此过程中效率很低8 → 9。然而,发现扁桃酸衍生物,特别是扁桃酸酯具有很大的潜力。环丙烷9的绝对立体化学已通过降解为1,1-二羧甲基-2-丁基环丙烷,并从己烯开始进行独立的对映选择性合成来确定。在优化的条件下,即。使用烯丙基碘化试剂并与Na 2 SO 3水溶液进行后处理以避免碘介导的聚合,可以以86%的收率生成(S)-9,并使用(S)扁桃酸甲酯作为改性剂有用的对映体纯度(94/6 er ) 被观测到。
Tertiary and Quaternary Carbon Formation via Gallium-Catalyzed Nucleophilic Addition of Organoboronates to Cyclopropanes
作者:Truong N. Nguyen、Jeremy A. May
DOI:10.1021/acs.orglett.7b03349
日期:2018.1.5
via homoconjugate addition of organoboron nucleophiles to diester- and ketone-functionalized cyclopropanes. Electron donor group cyclopropane substituents were not needed, allowing electron-deficient aryl, alkenyl, alkyl, and hydrogen-substituted cyclopropanes to be used. The catalytic conditions were compatible with alkenyl, alkynyl, and arylnucleophiles, including ortho-substituted aromatics, to
Scope and Mechanism for Lewis Acid-Catalyzed Cycloadditions of Aldehydes and Donor−Acceptor Cyclopropanes: Evidence for a Stereospecific Intimate Ion Pair Pathway
作者:Patrick D. Pohlhaus、Shanina D. Sanders、Andrew T. Parsons、Wei Li、Jeffrey S. Johnson
DOI:10.1021/ja8015928
日期:2008.7.1
In this work, the one-step diastereoselective synthesis of cis-2,5-disubstituted tetrahydrofuransviaLewis acid catalyzed [3 + 2] cycloadditions of donor-acceptor (D-A) cyclopropanes and aldehydes is described. The scope and limitations with respect to both reaction partners are provided. A detailed examination of the mechanism has been performed, including stereochemical analysis and electronic profiling
Stereospecific Formal [3+2] Dipolar Cycloaddition of Cyclopropanes with Nitrosoarenes: An Approach to Isoxazolidines
作者:Shyamal Chakrabarty、Indranil Chatterjee、Birgit Wibbeling、Constantin Gabriel Daniliuc、Armido Studer
DOI:10.1002/anie.201400885
日期:2014.6.2
The MgBr2‐catalyzed formal [3+2] cycloaddition of donor–acceptor activated cyclopropanes with nitrosoarenes offers a novel approach to various structurally diverse isoxazolidines. The reactions, which are experimentally easy to conduct, occur with complete stereospecificity and perfect control of regioselectivity. Product isoxazolidines can be readily transformed into α‐amino lactones by reductive
Synthesis of Substituted β-Styrylmalonates by Sequential Isomerization of 2-Arylcyclopropane-1,1-dicarboxylates and (2-Arylethylidene)malonates
作者:Roman A. Novikov、Yury V. Tomilov、Denis D. Borisov、Grigorii R. Chermashentsev
DOI:10.1055/a-1348-4311
日期:2021.7
A method has been developed for the synthesis of substituted β-styrylmalonates by conversion of 2-arylcyclopropane-1,1-dicarboxylates (ACDCs) in the presence of gallium trichloride into the corresponding 1,2-zwitterionic intermediates or (2-arylethylidene)malonates, followed by treatment with pyridine at room temperature leading to an isomerization of the emerging double bond. This method allows
General Method for the Synthesis of Phenyliodonium Ylides from Malonate Esters: Easy Access to 1,1-Cyclopropane Diesters
作者:Sébastien R. Goudreau、David Marcoux、André B. Charette
DOI:10.1021/jo802208q
日期:2009.1.2
A general method to access phenyliodonium ylides from malonates has been developed. These ylides provide easy access to a variety of useful 1,1-cyclopropane diesters using rhodium or copper catalysis. Moreover, the iodonium ylide of dimethyl malonate was obtained in 78% yield using improved conditions that involve a simple filtration step to isolate the desired product. This ylide was shown to be a