Silylformylation of chiral 1-alkynes, catalysed by solvated rhodium atoms

Solvated rhodium atoms, prepared by the metal vapour synthesis technique, p romote the silylformylaton reaction of variously substituted alkynes (RRCH) -R-1-C-2(CH2)(n)C equivalent to CH, with catalytic activities comparable wi th and even higher than more common species such as Rh-4(CO)(12). Z-Silylal kenals are exclusively formed in high yields (60-95%) indicating syn additi on both of CO and of the silane (Me2PhSiH) to the triple bond, The chemosel ectivity of the process (silylformylation vs. hydrosilylation) is highly af fected by the amount of catalyst employed (mmol of Rh species with respect to the alkyne reagent), by the steric requirements of the acetylenic substr ates and by the hydrosilane/alkyne molar ratio. When optically active acety lenes are treated in the presence of Me2PhSiH under carbon monoxide pressur e, the silylformylation reaction occurs with total retention of stereochemi stry of the stereogenic centre, even if it is at the alpha -position of the unsaturated moiety, to afford enantiomerically enriched beta -silylalkenal s.