Table. Pathological Features and Molecular Profile of Early-Onset Colorectal Cancer Pathological features Molecular profile Poor differentiation Microsatellite stability Mucinous tumors More likely to exhibit LINE-1 hypomethylation and TP53 sequence variations Signet-ring morphology Less frequently harbor KRAS, BRAF V600E, and APC sequence variations Perineural/venous invasion Promoter methylation of CpG islands Abbreviations: APC, adenomatous polyposis coli; BRAF, B-Raf; KRAS, K-Ras; LINE-1, long interspersed nuclear elements; TP53, tumor protein 53.

While attractive interactions between borane and olefin have been postulated to trigger various boron‐mediated organic transformations, proximity structures of these functional groups, other than the formation of weak van der Waals complexes, have never been directly observed. Here we show that a close intramolecular borane–olefin interaction operates in macrocyclic systems containing borane and olefinic groups obtained by multi‐step 1,2‐carboboration between a strained alkyne and 9‐borafluorene derivatives. Depending on Lewis acidity of the borane moiety and the size of the macrocycles, the magnitude of interaction changes, resulting in different reaction modes. The whole picture of the multi‐step reactions has been revealed experimentally with theoretical supports. The present finding may not only provide a deeper understanding of the fundamental boron‐mediated interaction but also lead to the development of new organic transformations involving molecular activation by boranes.

We conclude that the use of adaptive study design saves time in early phase research programs. This is achieved by abolishing the need for substantial amendments or by mitigating their impact on timelines and by using adaptive scheduling efficiencies.

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