ORGN 293 |
| As part of our ongoing research studying the possibility of using olefin metathesis for the preparation of new chiral phosphine ligands, we synthesized a series of phosphorus-containing trienes featuring two diastereotopic vinyl moieties. The diastereoselective RCM of these compounds to form novel highly functionalized P-stereogenic heterocycles featuring both an exo- and an endocyclic double bond was studied in detail. The position of the existing stereocenter is important in determining the diastereoselectivity of these reactions, with 1,3-stereoinduction being superior to 1,4-stereoinduction. The geometry of the double bonds conjugated to phosphorus and the nature of the substituent at the existing stereocenter also affect the stereochemical outcome of the reactions. The double bonds of the cyclic phosphinates are readily reduced in the presence of H2/Pd-C and the resulting saturated heterocycles undergo nucleophilic substitution at phosphorus with organometallic reagents to give acyclic P-stereogenic phosphine oxides with no loss of stereochemical information.
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New Reactions and Methodology
1:00 PM-5:00 PM, Tuesday, 28 March 2006 Georgia World Congress Center -- C301, Oral
Division of Organic Chemistry |
