Zusammenfassung
Condensation of D-arabinuronolactone (2) with L-cysteine methyl ester yields the bicyclic thiazolidinlactam 3 as a single diastereoisomer with the new bridgehead stereocenter in the (S) configuration. Regioselective activation of the alpha-hydroxy group leads to the triflate 4 without requiring protecting groups on the residual hydroxy groups. Subsequent azide exchange, reduction, and Boc ...
Zusammenfassung
Condensation of D-arabinuronolactone (2) with L-cysteine methyl ester yields the bicyclic thiazolidinlactam 3 as a single diastereoisomer with the new bridgehead stereocenter in the (S) configuration. Regioselective activation of the alpha-hydroxy group leads to the triflate 4 without requiring protecting groups on the residual hydroxy groups. Subsequent azide exchange, reduction, and Boc protection, yields the epimeric dipeptide mimetics 6 and 7. Compound 3 forms the single acetonide 9, which permits the regioselective alkylation of the gamma-hydroxy group of the bicyclic framework. Subsequent deprotection and exchange of the a-hydroxy functionality against a Boc-protected amino group (13) demonstrates the regioselective side-chain modification of bicyclic dipeptides.
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