A hydrogen borrowing reaction employing secondary alcohols and Ph* (MeC) ketones to give β-branched carbonyl products is described (21 examples). This new C-C bond forming process requires low loadings of [Cp*IrCl], relatively low temperatures, and up to 2.0 equiv of the secondary alcohol. Substrate-induced diastereoselectivity was observed, and this represents the first example of a diastereoselective enolate hydrogen borrowing alkylation. By utilizing the Ph* group, the β-branched products could be straightforwardly cleaved to the corresponding esters or amides using a retro-Friedel-Crafts reaction. Finally, this protocol was applied to the synthesis of fragrance compound (±)-3-methyl-5-phenylpentanol.

An iridium catalyzed method for the synthesis of functionalized cyclohexanes from methyl ketones and 1,5-diols is described. This process operates by two sequential hydrogen borrowing reactions, providing direct access to multisubstituted cyclic products with high levels of stereocontrol. This methodology represents a novel (5 + 1) strategy for the stereoselective construction of the cyclohexane core.

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The application of an iridium-catalyzed hydrogen borrowing process to enable the formation of α-branched ketones with higher alcohols is described. In order to facilitate this reaction, ortho-disubstituted phenyl and cyclopropyl ketones were recognized as crucial structural motifs for C-C bond formation. Having optimized the key catalysis step, the ortho-disubstituted phenyl products could be further manipulated by a retro-Friedel-Crafts acylation reaction to produce synthetically useful carboxylic acid derivatives. In contrast, the cyclopropyl ketones underwent homoconjugate addition with several nucleophiles to provide further functionalized branched ketone products.

The ICH M7 guidance provides a series of flexible control options for the control of (potentially) mutagenic impurities (PMIs) that fully align with key risk-based principles. This includes option 4, which leverages existing process knowledge and/or data to justify control of PMIs without the need for routine analytical release testing during manufacturing. One such technique highlighted uses systematic, semiquantitative calculations to define the degree of "purge" of PMIs within a synthetic route to an active pharmaceutical ingredient (API) based on physicochemical properties of the impurities in question, and the manufacturing process being undertaken. This paper introduces a consortium-led initiative, Mirabilis, which aims to build on the semiquantitative purge approach, and harmonize industry best practices by enabling the calculations to be conducted in a standardized, consistent, and reproducible manner. The development of an expert-derived knowledge base for the prediction of reactivity by enhancing expert opinion using evidence derived from the published literature and experimental data is also discussed. Furthermore, this paper describes the application of Mirabilis software for the processes involved in the synthesis of verubecestat, naloxegol oxalate, and camicinal.