Comparison of Solid-Phase and Solution-Phase Chiral Auxiliaries in the Alkylation/Iodolactonization Sequence to γ-Butyrolactones

Five prolinol-based chiral auxilaries have been compared for the stereoselective synthesis of γ-butyrolactones via the sequence of N-acylation, C α -allylation, and iodolactonization under both solution-phase and solid-phase conditions. Comparisons of stereoselectivity of both the C α -allylation and iodolactonization processes indicate that incorporation of a non-C 2-symmetric auxiliary as a polymer cross-link gives results superior to those obtained either in solution or with other non-C 2-symmetric auxiliaries and comparable to those observed using a polymer-supported pseudo-C 2-symmetric auxiliary.