Bulky mono-phosphite

Table 1. Hydroformylation using rhodium bulky mono phosphite catalysts ...

Phosphites have been used as ligands in Rh-catalyzed hydroformylation from the early days since their introduction in 1969.205 206 Identification of complexes occurred more recently. Ziolkowski and Trzeciak have studied extensively the use of phosphite ligands in the Rh-catalyzed hydroformylation of alkenes.207-210 The ligand tris(2-/er/-butyl-4-methylphenyl) phosphite (65) leads to extremely fast catalysis and in situ spectroscopy showed that under the reaction conditions only a mono-ligated complex [Rh(H)(CO)3(65)], (66), is formed due the bulkiness of the ligand.211-213... 

Attack on Unsaturated Carbon.- Bis(trimethylsilyl)phosphonite (14), prepared from ammonium phosphinate and hexamethyldisilazane, adds to o,p-unsaturated ketones (IS) to give high yields of mono- or disubstituted phosphinic acids. Low yields were obtained for enolisable ketones if (14) was prepared in situ from trimethylsilylchloride and triethylamine instead. Diethyl trimethyl-silyl phosphite (16) reacts readily with a,p-unsaturated imines to give solely 1,2-addition products (17), even in the presence of bulky Y-substituents, provided R Ws an aryl group. ... 

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