A new, organocatalytic approach to the hydrolytic deprotection of dithianes has been developed involving a low-toxicity imidazolium-ion-based catalyst in an aqueous medium. A complimentary solvent-free method without added water and involving a sacrificial aldehyde is also reported. The catalyst does not appear to operate by a specific-acid catalysis mechanism.

The first strategy for bringing about enantioselective azlactone dynamic kinetic resolution to generate orthogonally protected amino acids has been developed. In the presence of a C₂-symmetric squaramide-based catalyst, benzyl alcohol reacts with novel yet readily prepared tetrachloroisopropoxycarbonyl-substituted azlactones to generate trapped phthalimide products of significant synthetic interest with excellent enantiocontrol. These materials are masked amino acids which are demonstrably orthogonally protected: cleavage of the phthalimide can be achieved in the presence of the ester and vice versa. This process could be utilized to bring about a highly stereoselective ligation-type coupling of protected serines (at stoichiometric loadings) with racemic azlactones derived from both natural and abiotic amino acids. After deprotection, a subsequent base-mediated ON acyl transfer occurs to form a dipeptide.

The first strategy for bringing about enantioselective azlactone dynamic kinetic resolution to generate orthogonally protected amino acids has been developed. In the presence of a C₂-symmetric squaramide-based catalyst, benzyl alcohol reacts with novel yet readily prepared tetrachloroisopropoxycarbonyl-substituted azlactones to generate trapped phthalimide products of significant synthetic interest with excellent enantiocontrol. These materials are masked amino acids which are demonstrably orthogonally protected: cleavage of the phthalimide can be achieved in the presence of the ester and vice versa. This process could be utilized to bring about a highly stereoselective ligation-type coupling of protected serines (at stoichiometric loadings) with racemic azlactones derived from both natural and abiotic amino acids. After deprotection, a subsequent base-mediated ON acyl transfer occurs to form a dipeptide.

In the presence of a novel, tert-butyl-substituted squaramide-based catalyst, enolizable anhydrides react with alkylidene oxindoles to generate spirooxindole products of significant synthetic interest with excellent enantio- and diastereocontrol. The methodology is of wide scope and encompasses both homophthalic and glutaconic anhydride derivatives, which lead to structurally diverse products. Glutaconic acid-derived anhydrides undergo a clean post-cyclization decarboxylation process which is not a feature of reactions involving homophthalic acid-derived anhydrides. The unusual influence of reaction temperature on diastereocontrol has been probed, with reactions occurring at 30 °C and −30 °C delivering products epimeric at one stereocenter only, in near optical purity.

In the presence of a novel, tert-butyl-substituted squaramide-based catalyst, enolizable anhydrides react with alkylidene oxindoles to generate spirooxindole products of significant synthetic interest with excellent enantio- and diastereocontrol. The methodology is of wide scope and encompasses both homophthalic and glutaconic anhydride derivatives, which lead to structurally diverse products. Glutaconic acid-derived anhydrides undergo a clean post-cyclization decarboxylation process which is not a feature of reactions involving homophthalic acid-derived anhydrides. The unusual influence of reaction temperature on diastereocontrol has been probed, with reactions occurring at 30 °C and −30 °C delivering products epimeric at one stereocenter only, in near optical purity.

The highly enantioselective dynamic kinetic resolution (DKR) of azlactones by thiolysis has been achieved for the first time. Although both the parent alkaloid quinine and known C-5′-urea derivatives fail to promote the reaction effectively, a new class of C-5′-hydroxylated catalysts proved capable of catalysing the DKR of a range of azlactones derived from both unbranched- and, previously challenging, branched-chain amino acids in 84–92 % ee, including an example of the synthesis of an enantioenriched N-protected thioester derived from an extraterrestrial amino acid isolated from the Murchison meteorite.

This review charts the recent progress of two related, yet distinct organocatalytic processes: the desymmetrisation of meso-anhydrides and the dynamic kinetic resolution of azlactones. Driven by recent advances in catalyst design, both these processes have undergone something of a renaissance in recent years and are now becoming very powerful and versatile synthetic methodologies. The material is presented in a critical fashion and the material is organised by reaction type and catalyst class.

It has been demonstrated for the first time that a sulfide catalyst, utilised at 20 mol% loading, can promote methylene transfer to ketones in the presence of methyl triflate and an organic base. This metal-free methodology is of broad scope – both aliphatic and aromatic ketones (including trifluoromethyl ketones) can be converted to synthetically useful terminal epoxides in excellent yields at room temperature.