1,3‐Thia­zolidine derivatives from regioselective [2+3]‐cyclo­additions of azomethine yl­ides with thio­ketones

The title compounds, namely di­methyl (2RS)‐2,3‐di­phenyl‐1,3‐thia­zolidine‐5‐spiro‐2′‐adam­antane‐4,4‐di­carboxyl­ate methanol sol­vate, C₂₈H₃₁NO₄S·0.275CH₄O, and di­methyl (4RS)‐3,4‐di­phenyl‐1,3‐thia­zolidine‐5‐spiro‐9′‐(9′H‐fluorene)‐2,2‐di­car­box­ylate, C₃₁H₂₅NO₄S, were obtained from dipolar 2+3]‐cyclo­additions of an azo­methine yl­ide with adamantane­thione and thio­fluorenone, respectively. The structures show that the choice of thio­ketone affects the regioselectivity of the cyclo­addition. The asymmetric unit of the former structure contains two mol­ecules of the thia­zolidine derivative plus a site for a partial occupancy (55%) methanol mol­ecule. O—H?O and C—H?O interactions link two of each of these entities into closed centrosymmetric hexamers. The five‐membered ring in each structure has an envelope conformation.