A series of novel N-tert-butyl sulfinyl squaramide receptors have been designed and synthesized. Their interactions with a range of inorganic anions were studied in solution by H NMR spectroscopy. This new type of squaramide displayed better anion-binding abilities over conventional diphenyl squaramides. The single crystal analysis and DFT calulations implied the role of the tert-butyl C-H protons in binding Cl. The energies of C-H···Cl interactions were estimated to be 1.4-1.6 kcal/mol in solution.

A highly enantioselective [4 + 2] cycloaddition of allenoates with 2-olefinic benzofuran-3-ones catalyzed by (DHQD)2AQN, which allowed the synthesis of optically active dihydropyran-fused benzofurans, was developed.

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Highly Enantioselective [4 + 2] Cycloaddition of Allenoates and 2-Olefinic Benzofuran-3-ones.-Starting from 2-benzylidenebenzofuran-3-ones the synthesis of chiral dihydropyran-fused benzofurans is elaborated. Upon application of unsubstituted substrates the products are prepared in high yields as mixtures of two separable regioisomers, both of which are obtained with excellent enantiomeric excess. In contrast, application of substituted 2-benzylidenebenzofuran-3-ones provides only one regioisomer, albeit with significantly lower yield and enantiomeric excess. The utility of the reaction is demonstrated by further conversion of the products, e.g. by reduction of the carboxyl or alkene functionality. -(WANG, F.; LUO, C.; SHEN, Y.-Y.; WANG, Z.-D.; LI, X.; CHENG*, J.-P.; Org. Lett. 17 (2015) 2, 338-341, http://dx.