472-17-3Relevant articles and documents
Rhodium catalyzed hydroformylation of β-pinene and camphene: effect of phosphorous ligands and reaction conditions on stereoselectivity
Barros, Humberto J. V.,Ospina, Maria L.,Arguello, Eduardo,Rocha, William R.,Gusevskaya, Elena V.,Santos, Eduardo N. dos
, p. 150 - 157 (2007/10/03)
The effect of phosphorous ligands on the rhodium catalyzed hydroformylation of β-pinene and camphene has been studied. In unmodified systems, β-pinene undergoes a fast isomerization to α-pinene. At longer reaction times and higher temperatures, the isomerization equilibrium is shifted resulting in the 80 percent chemoselectivity for β-pinene hydrofromylation products (97 percent trans). The addition of various diphosphines or phosphites improves the chemoselectivity and shifts the hydroformylation towards cis aldehyde 3a. Both the rate and diastereoselectivity of the hydroformylation of β-pinene are largely influenced by the basicity of auxiliary ligands, but surprisingly no correlation between their steric characteristics and the diastereoselectivity of the catalytic system has been revealed for the ligands with cone angles 128-165 deg. The systems with more basic ligands show lower activities, higher diastereoselectivities and usually higher chemoselectivities in the β-pinene hydroformylation. Camphene gives linear aldehyde 6, with virtually 100 percent regio- and chemoselectivity in both modified and unmodified systems. The addition of phosphorous ligands favors the formation of endo isomer 6b:6a/6b ca. 1/1.5 , whereas the ratio ca. 1/1 unmodified systems. Neither steric nor electronic parameters of the ligands have been found to influence significantly the diastereoselectivity of the camphene hydroformylation.
Syntheses in the isocamphane series. V. A new synthesis of camphenilanic acid and isocamphenilanecarbaldehyde
Buchbauer
, p. 3 - 9 (2007/10/15)
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