Meso-phospholenes

The only notable success to date in the use of (salen)metal systems in catalysis of asymmetric cyanide addition to epoxides was achieved by Pietrusiewicz, who reported the aluminium-catalyzed desymmetrization of phospholene meso-epoxide (Scheme 7.23) in moderate ee [47]. Despite these significant efforts, a truly prac-... 

Pakulskia, Z. Pietrusiewicz, K. M. (2004) Enantioselective desymmetrization of phospholene meso-epoxide by nucleophilic opening of the epoxide.. Tetrahedron ... 

Scheme 13.34 summarizes what seems to be the only purely organocatalytic example of base-catalyzed rearrangement of a meso-cpoxide. In the presence of 50-100 mol% quinidine 66, the epoxy-3-phospholene 67 was slowly converted to the allylic alcohol 68 with up to 52% ee [70],... 

In this chapter, we attempt to review the current state of the art in the applications of cinchona alkaloids and their derivatives as chiral organocatalysts in these research fields. In the first section, the results obtained using the cinchona-catalyzed desymmetrization of different types of weso-compounds, such as weso-cyclic anhydrides, meso-diols, meso-endoperoxides, weso-phospholene derivatives, and prochiral ketones, as depicted in Scheme 11.1, are reviewed. Then, the cinchona-catalyzed (dynamic) kinetic resolution of racemic anhydrides, azlactones and sulfinyl chlorides affording enantioenriched a-hydroxy esters, and N-protected a-amino esters and sulftnates, respectively, is discussed (Schemes 11.2 and 11.3). 

Desymmetrization of meso-Epoxy Phospholenes to Allyl Alcohols via Rearrangement... 

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