136689-63-9Relevant academic research and scientific papers
Dirhodium(II) tetraacetate catalyzed (chlorovinyl)cyclopropanation of enol ethers and dienol ethers - A route to donor-substituted vinylcyclopropanes, ethynylcyclopropanes and cycloheptadienes
De Meijere,Schulz,Kostikov,Graupner,Murr,Bielfeldt
, p. 547 - 560 (2007/10/02)
2-Chloro- (4-Cl), 3,3-dichloro- (4-Cl2), and 2,3,3-trichlorodiazo-propene (4-Cl3) can easily be prepared in up to 70% yield by thermal fragmentation (Bamford-Stevens reaction), at 60°C in tetrahydrofuran, of the corresponding chloroacrolein tosylhydrazone sodium salts 3-Cl(n). Tetrahydrofuran solutions of (chlorovinyl)diazomethanes 4-Cl(n) thus obtained are used for cyclopropanation reactions of a large variety of alkenes. Under dirhodium(II) tetraacetate catalysis, yields of (chlorovinyl)cyclopropanes 6-Cl(n) [and of vinylcyclopropanes 6-H3 with diazopropene (4-H3)] are quite good especially from enol ethers. Dienol silyl ethers, 2-trimethylsiloxy-1,3-butadiene (12) and 1-(1'-trimethyl-siloxyvinyl)cyclohexene (15), react exclusively at the donor-substituted double bond, the resulting 1-siloxy-1,2-divinylcyclopropanes 13-X(n), 16-X(n) readily rearrange to cycloheptadiene derivatives 14 and 17-20 respectively. 2-Alkoxy-1-(chlorovinyl)cyclopropanes such as 6 o-Cl2, 6 p-Cl2, 6 p-Cl3 can be transformed to synthetically valuable 2-alkoxy-1-ethynylcyclopropanes 27 o,p, which are also obtained by direct ethynylcyclopropanation of enol ethers with diazopropyne (28). This latter method provides the first known access to 2-siloxy-1-ethynylcyclopropane 25m.
