13757-43-2Relevant academic research and scientific papers
Convenient preparation of a cyclopropanation reagent: α-Siloxymethyliron complex
Du, Hong,Yang, Fukang,Mahmun Hossain
, p. 1371 - 1377 (1996)
A convenient preparation of α-siloxymethyliron complex (7) was developed from commercially available s-trioxane and/or paraformaldehyde. For synthetic utility, iron methylidene complex (8) was generated in situ from the α-siloxymethyliron complex (7) and cyclopropanes (10) by treatment with alkenes.
Mechanism-based design and optimization of a catalytic electrophilic cyclopropanation without diazomethane
Tchawou, Augustin A. S. W.,Raducan, Mihai,Chen, Peter
, p. 180 - 191 (2017)
Iodomethylboron compounds, either the trifluoroborate or a boronic ester, cyclopropanate electron-rich olefins and unprotected allylic alcohols with Pd catalysts according to a novel, designed catalytic cycle. Proposed intermediates in a "diverted Heck" mechanism are observed by means of spectroscopic studies and by isolation and X-ray crystallographic characterization, which together with reaction kinetics point to a separation of rate-determining and product-determining steps, and a mechanism-based optimization of the yield, selectivity, and scope of the catalytic electrophilic cyclopropanation. The reaction with crystalline, air-stable, nonhygroscopic, and nontoxic reagents provides an alternative to Simmons-Smith-type reactions, as well as cyclopropanation procedures that require the use of diazomethane.
Mild Ring-Opening 1,3-Hydroborations of Non-Activated Cyclopropanes
Wang, Di,Xue, Xiao-Song,Houk, Kendall N.,Shi, Zhuangzhi
supporting information, p. 16861 - 16865 (2018/11/27)
The Brown hydroboration reaction, first reported in 1957, is the addition of B?H across an olefin in an anti-Markovnikov fashion. Here, we solved a long-standing problem on mild 1,3-hydroborations of non-activated cyclopropanes. A three-component system including cyclopropanes, boron halides, and hydrosilanes has been developed for borylative ring-opening of cyclopropanes following the anti-Markovnikov rule, under mild reaction conditions. Density functional theory (M06-2X) calculations show that the preferred pathway involves a cationic boron intermediate which is quenched by hydride transfer from the silane.
CYCLOPROPANATION
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Page/Page column 4; 5; 7, (2015/05/26)
A method of preparing a cyclopropane ring-bearing compound of the formula (I) in which R1 and R2 are independently selected from C1-C10 alky], optionally substituted, or R1 and R2 together with the bonds linking them to the cyclopropane ring, form a monocyclic or bicyciic ring system, which may comprise at least one hetero-atom, comprising the reaction of a compound of formula (II) in which R1 and R2 have the significances hereinabove defined, with a compound of formula (III) in which X is selected a nucieofuge selected from halides and pseudohalides and Y is an electro flige selected from boranes and borates, in the presence of a metal catalyst complex selected from those that a useful for catalytic cyclopropanation and those useful for catalyzing Heck coupling. The method prov ides a particularly easy and non-hazardous method of cyclopropanation.
A palladium-catalyzed methylenation of olefins using halomethylboronate reagents
Hartog, Tim Den,Toro, Juan Manuel Sarria,Chen, Peter
supporting information, p. 1100 - 1103 (2014/03/21)
Methylenation of electron-rich olefins is a highly challenging reaction, for which we have developed a new methodology exploiting Pd-catalysis and halomethylboronate reagents, the latter replacing diazomethane and zinc carbenoids as methylene donors. Optimization of the reaction for norbornene and extension to several other olefins are reported, with reasonable-to-excellent yields of cyclopropanes in combination with β-H elimination products. Several mechanisms are plausible for this methylenation reaction.
Conversion of non-activated alkenes into cyclopropanes with lithiated sulfones under nickel catalysis
Gai, Yonghua,Julia, Marc,Verpeaux, Jean-Noel
, p. 817 - 829 (2007/10/03)
Summary -Lithiated alkyl ierf-butyl sulfones convert alkenes into cyclopropane derivatives under nickel catalysis. The new reaction appears to differ from the known cyclopropanation reactions from both the stereochemical and the electronic points of view. Elsevier.
Photocyclization of Cyclononene and Cycloundecene
Haufe, Guenter,Tubergen, Mark W.,Kropp, Paul J.
, p. 4292 - 4295 (2007/10/02)
Irradiation of cyclooctene (7b) and cycloundecene (7d) in pentane afforded cis-bicyclononane (10b) and cis-bicycloundecane (10d), respectively.Small amounts of the fragmentation products 1-undecene (14d) and 1-undecyne (15d) were also obtained from cycloundecene (7d).The photobehavior of the series of medium- and large-ring alkenes 7a-e is compared.Aside from E Z isomerization, the principal pathway in each case involves rearrangement of the ?,R(3s) excited state to the cycloalkylidene intermediate 8, which undergoes predominant, if not exclusive, 1,5-transannular insertion to afford the corresponding cis-bicycloalkanes (10).The cycloalkylidene 8 formed in this way exhibit behavior somewhat different from those generated by other methods.The possible contributory role of carbene intermediates derived from ?,R(3s) excited states in E Z photoisomerization of acyclic alkenes is also discussed.
TERMINATION REACTIONS OF C5-C12 CYCLOALKYL RADICALS AND CARBENES
Wojnarovits, Laszlo
, p. 1449 - 1452 (2007/10/02)
Reactions of C5-C12 cycloalkyl radicals and carbenes produced during radiolysis, vacuum-u.v. photolysis, and decomposition of cycloalkanone p-tosylhydrazones were investigated.The disproportionation to combination ratios of radicals are ca. 1 and agree with the ratios of linear secondary radicals.The disproportionation smaller cycloalkyl radicals yields cis-cycloalkenes and cycloalkanes; from C9 and C10 cis- and trans-cycloalkenes and cycloalkanes and from C11 and C12 trans-cycloalkenes and cycloalkanes are produced.Both atoms of H2 given off in the elimination reaction from excited cycloalkane molecules orginate from the same carbon atom and in this process carbenes are formed.Rearrangement of small (C5, C6) and large (C11, C12) cycloalkylcarbenes in the solvent of the given cycloalkane occurs by 1,2-hydrogen migration.C7-C10 carbenes rearrange both by hydrogen atom migration and transannular insertion.
