The condensation of a primary alkylamine and a ketone adorned with alkyl substituents is usually reliable in forming a, herein termed, alkyl-imine, from which there are a plethora of reduction protocols to form the corresponding a-branched secondary alkylamine. In some cases, however, steric hindrance or adverse electronic effects on either the amine or ketone component can preclude alkyl-imine formation, leading to failure of the CRA process. A potential solution to this problem could be realized via addition of a carbon nucleophile to an alkyl-aldimine rather than a hydride to the alkyl-ketimine; the steric features of the product a-branched secondary alkylamine could be partitioned between an aldehyde and the incoming carbon nucleophile rather than confined to the ketone unit alone. Despite almost 100 years of efforts towards a solution to this simple idea, a general method for the addition of organometallic nucleophiles to alkyl-imines or iminium ions derived from primary alkylamines and alkyl-substituted aldehydes has largely eluded synthetic chemists. Only when reactivity-augmenting auxiliary groups are deployed on either the amine or carbonyl component does an effective and general transformation result: organometallic additions to Ellman's tert-butanesulfinamide derivatives, for example, have become the benchmark for this type of reaction (Figure ). Although one advantage of such auxiliaries is the opportunity to exert control over the stereochemistry at the newlychiral a-amino carbon centre, they nonetheless suffer from the well-established drawbacks of auxiliary use, namely the requirement for installation and removal and associated issues with functional group compatibility, and poor overall atom economy. Several additional steps are also required to form secondary or tertiary amine products, with cyclic tertiary amine motifs presenting a significant challenge The main reason that organometallic additions to non-activated alkyl imines fail can be ascribed to two factors: the low pKa of the C-H bonds adjacent to the carbon-nitrogen double bond, and the low electrophilicity of the carbon-nitrogen double bond. Most common organometallic reagents, with a few notable exceptions, are sufficiently basic to deprotonate the a-C-H bond in these alkyl-imine/iminium species and lead to the corresponding enamine; in contrast to their- -carbon-oxygen congeners, the carbon-nitrogen double bond is insufficiently electrophilic for 1,2-addition to adequately compete with this deprotonation, thereby precluding the desired reaction. As an alternative, carbon-centred radicals have been shown to effectively add to a range of activated surrogates, such as hydrazones, oximes, carbamoyl and sulfonyl imines. The charge-neutral and non-basic nature of alkyl-radicals addresses the deprotonation problems associated with organometallic additions, however, their lower nucleophilicity often prevents efficient 1,2-addition to nonactivated imines, and tailored activating substituents on the aldehyde or reactivity augmenting auxiliaries on the amine component are required. Furthermore, the nitrogen centred radical resulting from 1,2-addition to a C=N bond often needs stabilization by the N-substituent, meaning that auxiliary groups once again become prerequisite for an effective transformation.