Ligation of chiral bis-3,4-diazaphospholanes to Rh(acac)(CO)2 yields highly active, enantio-, and regioselective catalysts. Modification of diazaphospholanes via amino-acid coupling chemistry enables the construction of ligand libraries and polymer supported catalysts. Application of these ligands to a small array of substrates demonstrates effective tuning of ligand structure vis-a-vis the substrate along with demonstration of effective immobilization of the Rh catalyst. The robustness of diazaphospholane-based catalysts enables multiple hydroformylation-wittig olefination sequences to be effected using one-pot and a single catalyst loading. Hydroformylation of alkenes followed by olefination with stabilized ylides bearing vinyl esters can be repeated iteratively to yield a,?-polyester tetramers with high enantioselectivity. Hydroformylation under unusual conditions, either low temperature or low pressure, enable new mechanistic insights and the isolation and characterization of long-sought intermediates in hydroformylation.

Enantioselective hydroformylation with bis-3,4-diazaphospholanes

245th National Meeting (2013)

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