Synthesis, Table of Contents Synthesis 2021; 53(01): 182-192DOI: 10.1055/s-0040-1707351 paper © Georg Thieme Verlag Stuttgart · New York Diastereoselective Synthesis of Alkylated 1,4-Cyclohexadiene Esters Using Epimeric Pyrroloimidazolones Ngan Tran , Dusty Cadwallader , Costa Metallinos∗ Department of Chemistry, Brock University, 1812 Sir Isaac Brock Way, St. Catharines, ON, L2S 3A1, Canada Email: cmetallinos@brocku.ca › Author Affiliations Recommend Article Abstract Buy Article All articles of this category Abstract A pair of ortho-benzoate esters containing epimeric pyrroloimidazolones undergo sequential Birch reduction and diastereoselective alkylation to provide products ranging from 88:12 to >95:5 diastereomeric ratio (dr) for the syn-epimer, and 50:50 to 95:5 dr for the anti-epimer. The stereochemistry of the products is confirmed by a combination of X-ray crystallography on a key anti-epimer-derived product, in combination with specific rotation measurements of enantiomers that are prepared from the syn or anti starting materials. A diastereomerically pure allyl-substituted substrate is shown to undergo Cope rearrangement, which transposes the quaternary chiral center to a remote position without racemization. This work is complementary to asymmetric reductive alkylation reported previously by Schultz using anisole substrates with chiral benzamide auxiliaries in that the pyrroloimidazolones act as surrogates for the methoxy group. Key words Key wordsBirch reduction - asymmetric - alkylation - lithiation - diastereoselective - epimeric - pyrroloimidazolone - Cope rearrangement Full Text References References 1a Rabideau PW, Marcinow Z. Org. React. 1992; 42: 1 1b Birch AJ. J. Chem. Soc. 1944; 430 1c Birch AJ. Pure Appl. Chem. 1996; 68: 553 1d Hook JM, Mander LN. 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