In the hydroformylation of (+)(S)-3-methylpent-1-ene the extent of racemization of the synthesized dissymmetric aldehydes is shown to decrease with increasing pressure of carbon monoxide; the ratio of erythro- to threo-2,3-dimethylpentanal formed differs considerably from the diastereoisomeric equilibrium value.
Solvated rhodium atoms, prepared by the metal vapour synthesis technique, promote the silylformylaton reaction of variously substituted alkynes (RRCH)-R-1-C-2(CH2)(n)C equivalent to CH, with catalytic activities comparable with and even higher than more common species such as Rh-4(CO)(12). Z-Silylalkenals are exclusively formed in high yields (60-95%) indicating syn addition both of CO and of the silane (Me2PhSiH) to the triple bond, The chemoselectivity of the process (silylformylation vs. hydrosilylation) is highly affected by the amount of catalyst employed (mmol of Rh species with respect to the alkyne reagent), by the steric requirements of the acetylenic substrates and by the hydrosilane/alkyne molar ratio. When optically active acetylenes are treated in the presence of Me2PhSiH under carbon monoxide pressure, the silylformylation reaction occurs with total retention of stereochemistry of the stereogenic centre, even if it is at the alpha -position of the unsaturated moiety, to afford enantiomerically enriched beta -silylalkenals.
Synthesis of (+)(S)-3-Methyl-1-pentene
作者:PIERO PINO、LUCIANO LARDICCI、LUIGI CENTONI
DOI:10.1021/jo01092a002
日期:1959.10
Trigonal bipyramidal platinum complexes as models for ziegler-nasa catalytic sites
作者:P. Ammendola、M.R. Ciajolo、A. Panunzi、A. Tuzi
DOI:10.1016/0022-328x(83)80142-9
日期:1983.10
Simple access to highly enantiomerically enriched (S)-3-methyl-1-pentanol, (S)-3-methyl-1-pentene, (2R,3S)-2-deuterio-3-methyl-1-pentanol and (2S,3S)-3-methyl-2-pentanol from natural (L)-isoleucine