Transition metal catalyzed asymmetric hydrocarbonylation of functionalized alkenes.

Abstract

Aromatic and aliphatic vinyl sulfones and sulfoxides have been hydroformylated with CO/H$\sb2$ in the presence of the zwitterionic rhodium complex, 1,5-cyclooctadiene rhodium(I) tetraphenylborate, (1,5-(COD)Rh$\sp+(\eta\sp6$-$\rm C\sb6H\sb5)B(C\sb6H\sb5)\sb{3\sp-}),$ to give previously unknown aldehydic sulfones and sulfoxides in excellent yields and regioselectivities. The hydroformylation of phenyl vinyl sulfoxide in the presence of 1,5-(COD)Rh$\sp+(\eta\sp6$-$\rm C\sb6H\sb5)B(C\sb6H\sb5)\sb{3\sp-}$ and the chiral phosphine ligand, BINAP, demonstrated considerable stereodifferentiating ability (up to 50% de). The hydroesterification of vinyl esters with CO/MeOH/bis(triphenylphosphine)palladium(II) dichloride, $\rm ((PPh\sb3)\sb2PdCl\sb2),$ has been studied. The critical necessity of catalytic amounts of acid, such as $\rm H\sb3PO\sb4$ (1 mol% relative to substrate), was revealed. This reaction is also catalyzed by the cationic palladium(II) hydrido complex, $\rm \lbrack (Cy\sb3P)\sb2Pd(H)(H\sb2O)\rbrack\sp+BF\sb{4\sp-}.$ Lactic acid derivatives can be synthesized with modest ee's (up to 30%) using $\rm \lbrack (Cy\sb3P)\sb2Pd(H)(H\sb2O)\rbrack\sp+BF\sb{4\sp-}$ in the presence of BINAP. Design and synthesis of new chiral borate ligands and their rhodium complexes have been undertaken.