[RuCl2(CO)3]2/Et3N and (eta 3-C3H5)RuBr(CO)3/Et3N are highly effective catalyst systems for carbonylative cyclization of allylic carbonates with alkenes to give the corresponding cyclopentenones in high yields. For example, treatment of allyl methyl carbonate (1a) with 2-norbornene (2a) in the presence of a catalytic amount of [RuCl2(CO)3]2 (2.5 mol %) and Et3N (10 mol %) at 120 degrees C for 5 h under
Intermolecular additive free microwave (MW) promoted and cobalt octacarbonyl mediated Pauson-Khand reaction (PKR) performance was improved for estrone ring extension. The reaction development with norbornene and cyclopentene produced cyclopentenones in yields of comparable levels with those previously obtained with the aid of chemical additives as promoters. The PKRs with norbornene demonstrated that a low cobalt complex concentration increases yields, especially for the aliphatic alkynes. Furthermore, a boost for the MW PKR could be obtained by a gradual cobalt complex addition. These expedients combined with the use of an excess of free and cobalt complexed alkyne led to successful estrone ring system extension with various alkynes. (C) 2008 Elsevier Ltd. All rights reserved.
作者:J. David Ricker、Vahid Mohammadrezaei、Thomas J. Crippen、Austin M. Zell、Laina M. Geary
DOI:10.1021/acs.organomet.8b00810
日期:2018.12.24
The chemistry is done using equimolar amounts of alkyne, alkene, and dicobalt octacarbonyl, and is performed directly from the acetylenic component without having to presynthesize a cobalt-alkyne complex. Terminal acetylenes were suitable substrates, as was solidcalciumcarbide, and the corresponding adducts were isolated in good yields. Furthermore, two sequential [4+3] and [2+2+1] cycloadditions were