Dioxolanones aldol reaction

Aldol reactions of chiral dioxolanones (113) and (114) are summarized in Scheme 6 and Table 9. ° With both (113) and (114), essentially perfect diasterofacial selectivity is observed. The simple dia-stereoselection is modest to good, and is dependent on the enolate counterion. For the lithium and magnesium enolates, the sense of simple diastereoselection is the same as is observed with the achiral dioxolanone (107) and the chiral dioxolanone (110). Use of the zirconium enolate generally reverses the sense of simple diastereoselection, although the isomer ratios are not very high in some cases. 

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