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The first general synthesis of 2-halomethyleneoxetanes, realized by the reaction of 2-methyleneoxetanes with N -halosuccinimides (NXS), is reported. The relative diastereoselectivities of the transformations were dependent on the halogen of NXS, while alternative reaction outcomes were influenced by substituents on the oxetane. Quantum mechanical calculations and molecular dynamics simulations exploring the basis of the observed diastereoselectivities are described. These highly strained heterocycles underwent standard cross-coupling reactions, demonstrating their utility as synthetic intermediates.

Invariant natural killer T (iNKT) cells play an important role in many innate and adaptive immune responses, with potential applications in cancer immunotherapy. The glycolipid KRN7000, an α-galactosylceramide, potently activates iNKT cells but has shown limited anticancer effects in human clinical trials conducted so far. In spite of almost three decades of structure-activity relationship studies, no alternative glycolipid has yet emerged as a superior clinical candidate. One reason for the slow progress in this area is that standard mouse models do not accurately reflect the specific ligand recognition by human iNKT cells and their requirements for activation. Here we evaluated a series of KRN7000 analogues using a recently developed humanized mouse model that expresses a human αTCR chain sequence and human CD1d. In this process, a more stimulatory, previously reported but largely overlooked glycolipid was identified, and its activity was probed and rationalized via molecular simulations.