75751-18-7Relevant academic research and scientific papers
REACTIONS OF DIAZOALKANES WITH UNSATURATED COMPOUNDS. 7. CATALYTICAL CYCLOPROPANATION OF 1-ALKOXY-, 1-ACETOXY-, AND 1-(TRIMETHYLSILYLOXY)BUTA-1,3-DIENES WITH DIAZOMETHANE
Tomilov, Yu. V.,Kostitsyn, A. B.,Shulishov, E. V.,Khusid, A. Kh.,Nefedov, O. M.
, p. 2513 - 2517 (2007/10/02)
Cyclopropanation of 1-butadienyl ethers or esters with diazomethane proceeds selectively in the presence of (PhCN)2PdCl2, as opposed to CuCl, at the less polar terminal double bond in these dienes when the molar proportions of reactants and catalysts are 1:(1.3-2):(0.002-0.005) to give the 2-cyclopropylvinyl ethers or esters in yields of 80-85percent.
THE DIAZO ROUTE TO 2-VINYLCYCLOPROPYLIDENES
Krimse, Wolfgang,Chiem, Pham Van,Henning, Paul-Georg
, p. 1441 - 1452 (2007/10/02)
2-Vinylcyclopropylidene (2), 3-methyl-2-vinylcyclopropylidenes (79,80) and 2-(1-propenyl)cyclopropylidenes (95,97) were generated from the corresponding nitrosoureas in methanol at room temperature.The diazo route is initiated by the formation of 2-vinylcyclopropanediazonium ions (e.g. 43) which do not undergo 1,3-carbon shifts.No cyclopentenyl products were found in weakly basic methanol where the diazonium ions prevail.Ring opening of the diazonium ions gives pentadienyl cations and products derived therefrom.Delocalisation of the pentadienyl cations was demonstrated by the distribution of deuterium and methyl labels.In the presence of strong base, 1-diazo-2-vinylcyclopropanes (e.g. 48) arise by deprotonation of the diazonium ions.Rearrangement of 48 was excluded by independent generation of the potential product, 4-diazocyclopentene (103).Substantial quantities of 3-methoxycyclopentene (108) were obtained from 103, but not from 48.The 2-vinylcyclopropylidenes 2, 79 and 95, arising by loss of nitrogen from the corresponding diazo compounds, undergo allene formation and Skatteboel rearrangement competitively.Cis-oriented methyl groups at either C-2 (81) or C-2' (97) prevent the Skattebol rearrangement.The cyclopentenylidenes 3 and 83 yield 4-methoxycyclopentes (52,86) in excess over cyclopentadiens (4,84).In the presence of methyl vinyl ether, cycloaddition of 3 and electrophilic addition of 3-cyclopentenyl cation (51) occured in a 1:14 ratio.Stereospecific formation of 52 indicates protonation of a 'foiled carbene' (3a) to give a bishomocyclopropenyl ion (51a).Our studies confirm that the various routes to 2-vinylcyclopropylidenes converge at the carbene stage.
