Carbonyl compounds supramolecular chemistry

Mine [7] and Kelly [8] were the first to prepare synthetic equivalents of this bidentate motif, using biphenylene diols as catalysts. Shortly after Etter had studied the hydrogen bonding patterns in supramolecular assemblies of various carbonyl compounds [9, 10], Curran introduced diarylurea derivatives as further bidentate organocatalysts [11, 12]. This interplay between supramolecular chemistry and non-covalent catalysis has turned out to be very fruitful ever since [13-15]. Schreiner subsequently showed that thioureas are also potent organocatalysts, which offer several advantages compared to urea derivatives, e.g., better solubility [13, 16]. In a proof-of-principle study, thiourea derivative 1 (Fig. 1, right) was used to catalyze the Diels-Alder reaction shown in Scheme 1 [16]. 

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