Oxazolidinethione and Oxazolidineselone Chiral Auxiliaries

Silks and co vorkers reported anti-selective aldol reactions in conjunction vith their investigations on chiral selenium compounds [39]. They discovered that bidentate oxyaldehydes precomplexed vith TiCl4 led to anti aldol products in good yield and vith excellent stereoselectivity, as sho vn in Table 2.35, entries 1 and 2. Presumably, this chelation-controlled reversal of syn/anti selectivity is a phenomenon similar to that vhich Ghosh and co vorkers exploited to produce syn aldols from aminoindanol chiral auxiliaries. Both benzyl and isopropyl oxazolidineselone chiral auxiliaries have comparable anti diastereoselectivity. 

Acenaphthene-derived anti aldol reactions with respective aldehydes. 

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